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AUTHOR Conrey, KathleenTITLE Lecture Notes on Human Anatomy. Part One, Fourth
Edition.PUB DATE Sep 89NOTE 79p.; For related documents, see SE 051 219-221.
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ABSTRACT
During the process of studying the specific coursecontent of human anatomy, students are being educated to expand theirvocabulary, deal successfully with complex tasks, and use a specificway of thinking. This is the first volume in a set of notes which aredesigned to accompany a lecture series in human anatomy. This volumeIncludes discussions of anatomical planes and positions, bodycavities, and architecture; studies of the skeleton including bonesand joints; studies of the musculature of the body; and studies ofthe nervous system including the central, autonomic, motor andsensory systems. (CW)
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PartFourth Edition
by KATHLEEN CONREY
9
LECTURE
NOTES
onHUMAN
ANATOMY
Part OneFourth Edition
The author is a Professor of Natural Sciences at El Camino College. She holds a master's degreefrom the Department of I luman Anatomy, University ofCalifornia, San Francisco, and has been
teaching human anatomy at the community college level since 1967.
by KATHLEEN CONREY
Aramaki Design & Publications12077 Jefferson Boulevard, Culver City, California
(213) 822-9800
Fourth Edition, September, 1989Copyright @1988 by Kathleen Conrey
All rights reserved No part of this publicati9n may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise, without the prior written permission of the copyright owner.
First edition and first printing 1982
Printed in the United States of America
TABLE OF CONTENTSPREFACE
INTRODUCTIONAnatomical PositionPlanesBody CavitiesMiscellaneous TermsBody Architecture
BONE TERMINOLOGY
OSSIFICATIONSpecial TermsIntramembranousEndochondralSummary
iii
1
1
23
33
4
5
5
5
7
ARTHROLOGY 9Joint Classification 9Parts of a Synovial Joint 9Joint Movements 10Other Synovial Sacs 10
SPECIFIC JOINT FEATURES 11Shoulder Joint 11
Elbow Joint 11Hip Joint 11
Sacral Joints 12Patello-Femoral Joint 13Knee Joint 13
GROSS ANATOMY OF MUSCLES 15Origin and Insertion 15Action 15
MUSCLES OF TIIE HEAD 16Facial Expression 16Mastication 17
MUSCLES OF THE NECK & DEEP TORSO 18Strap Muscles 18
Suprahyoid Group 18
Infrahyoid Group 18Posterior Triangle 18
Breathing Muscles 19
Posture Muscles 20Deep Back & Neck 20
MUSCLES OF POSTERIOR ABDOMINAL WALL 21
Lecture Notes Part I i Table of Contents
MUSCLES OF ANTERIOR ABDOMINAL WALLDescent of Testes
2224
UPPER LIMBMooring Muscles 25Shoulder Joint 27Elbow Joint 30Wrist and Finger Joints 32
LOWER LIMBHip and Thigh 35Lower Leg 39
NERVOUS SYSTEM INTRODUCTIONBasic Terminology and Basic Concepts 43
SPINAL CORD ANATOMY & SPINAL NERVES 45Spinal Reflex Arc 45Spinal Cord Terminology 45Spinal Nerves and Their Distribution 46
AUTONOMIC NERVOUS SYSTEM 48
CRANIAL NERVES 51
VENTRICLES, SPINAL FLUID, MENINGES, BLOOD SUPPLY 53Ventricles 53Cerebral Spinal Fluid 53Meninges 54Venous Drainage of the Brain 55Blood Supply to Brain 55Blood Brain Barrier 55
EMBRYOLOGY OF THE BRAIN 56
ADULT ANATOMY OF THE BRAIN 59Rhombencephalon 59Mesencephalon 59Prosencephalon 60
MAJOR PATHWAYS 63
GENERAL SENSORY RECEPTORS 65
THE EYE 67
THE EAR 70
Lecture Notes Part I ii Table of Contents
PREFACEI have written this book to make your job asa student easier. I am writing this preface inhopes that Ican help you to
Perhaps the most important objective becauseget beyond the they aregoal oriented of a college education is to produce meant to beview of education kept secret, but(memorizing specific graduates with trained minds. because they are
secondary processes as the "hiddenagenda" of a college education. They are
hidden, not
course conten4) to thatof a larger view, i.e. an awareness of whatthe education process is and how it works.
Perhaps the most important objective of acollege education is toproduce graduates with
of acqng a fled and dealt with on atrained minds. The The act of thinking requiresprocess
into the open, demysti-
trained mind is a process that oper- language.
rarely articulated. Jris my view that the student will be betterable to keep his or her balance in the courseand will be better able to gain satisfactionfrom the learning process if this "hidden
agenda" is brought out
,
conscious level.
ales on several different levels simultane-ously. On the most obvious level, the studentis exposed to a body of subject material andis expected to memorize it and to answerquestions about it on examinations. For ex-ample, in anatomy you will learn the names,locations, and identifying features of all ofthe bones of the body, and you will beexpected to identify them and answer ques-tions about their features on examinations.
This part of the process is specificallycontent oriented and is usually theonly process thatmost people areaware of when theythink about acourse in anatomy.h is my belief how-ever, that there areseveral less obvious things happening dur-ing the content oriented learning process de-scribed above.
One of the things that happens simultane-ously with the study of specific coursecontent, is that a student's vocabularygrows. This is an important part of the pro-cess of acquiring a trained mind, becausethe act of thinking requires language; ideascannot be expressed without the accurateuse of words. Acquisition of a larger vo-cabulary is especially important in any spe-cialized subject area such as law or medi-cine. Since anatomy is a foundation coursefor all medically related studies, this course
of study places a lot ofMONI=1MINIMIa1111M111ImimmiPOMIN1111110 emphasis on words
Learning thehuman bodseemingly i
anatomy of they is a huge andmpossible task.
These secondary levels to the process maybe just as important or perhaps even moreimportant than mastery of the actual coursecontent; it may be useful to think of these
and word roots.
Another part of thehidden agenda ofstudying specific
course content is theexpectation that by doing so a person willacquire personal organizational skills. Thisis a process that involves learning how tobreak a large and complex task clown intosmaller parts that are more manageable.
For example, learning the anatomy of thehuman body is a huge and seemingly impos-
Lecture Notes Part 1 iii Preface
sibk k&a. We begin by breaking the coursedown into six units: slatetal system, muscu-lar system, nervous system, histology, andinternal viscera (two units), allowingapproximately two weeks of time per unit.Next we will focus on each in turn, begin-ning by breaking that unitdown into smaller sec-tions, breaking the sec-tions down into subsec-tions, and so on.
Thus far you will be guidedby the organization of this bookand the design of the class schedule, but atsome point you will need to develop a per-sonal way of breaking the task down to whatyou can do a day at a time. The key word inthis idea is the word personal. There is noright or wrong way to develop these man-agement skills, the process will differ foreach one of you; you will find your ownunique methods. So, whenever you react tocollege in general and to this course in par-ticular with the feeling that "it is impossible,there is too much information" , or "how canI do it?" . try to make the shift to "How canLdo it ? ", and
2. illustrate (give examples or use ananalogy, or visualize, or draw)
3. classify (organize into set and subset)
4. sequence properly
S. compare /contrast (similaritiesIdzffer-ences)
Break the task down towhatyou can do a day
at a time.
your answersKill come, a dayat a time.
Finally, the mostimportant partof the hiddenagenda of a col-lege education in the Western tradition is toproduce graduates who have acquired aspecific set of critical thinking skills thatare highly valued by Western culture. It isbelieved that the discipline of using thisparticular set of skills has much to do withacquiring the ability to learn and thinkrather than just memorizing information.Here is a list of these skills, starting with themost simple tool and ending with the mostcomplex :
6. be clear about cause vseffect
7. analyze parts and furze-tions
Brief examples of 11&,./ the above thinkingskills are used in this anatomy coursefollow:
1. You will be given a precise definitionof the term "sagittal" , and you will betaught how to identify the lunate bone ofthe wrist.
2. During lecture your instructor willgive you an example of a muscle that hasa reversible origin and insertion
3. The lecture on joints will be structuredaround the various ways in which joints
are classified.
It is believed that the discipline ofusing this particular set of skills
has much to do with acquiring theability to learn and think.
1. define (or rianze or identify)
Lecture Notes Part I
4. The chapterin this bookwhich describesendochondralossification will
list the steps of theprocess in their
correct sequence.
S. When you are studying the autonomicnervous system you will construct a chartthat compares the sympathetic vs theparasympathetic nervous systems.
6. During the lecture on the pancreas youwill learn to distinguish between thecause of diabetes and the effect of diabe-tes.
7. When you study the central nervoussystem you will analyze the parts of the
iv Preface
CNS in terms of their embryologicalorigin.
Your reading, listening, note taking andstudy efficiency will be greatly improved inany subject if you will watch for the use ofthese thinking skills, since recognition willimmediately signal to you what informationis important vs unimportant in terms ofcourse content. You will begin to notice thatall textbooks and all lectures are organizedaround these principles.
Furthermore, since all examination ques-tions are also based on this specc ap-proach to organized thinking, you can mostefficiently prepare yourseiffor examinationsby drilling yourself on information that hasbeen first organized in these specific ways.By doing so you will discover that you havea very powerful key to academic success.
And finally, even more power will comewhen you begin to use these skills yourself toorganize a body of informatio,1 that you arethinking about or wrestling with.
In summary, keep in mind that during theprocess of studying specific course contentin human anatomy, you are simultaneouslyacquiring a trained mind by theprocesses ofexpanding your vocabulary, learning to dealsuccessfully with large and complex tasks,and then finally by learning a specific wayof thinkino that will liberate you from blindmemorization and regurgitation.
Lecture Notes Part I Preface
INTRODUCTION To ANATOMY
In the study of anatomy it is frequently necessary to use adjectives referring to anatomical position and location,including terms for directions and planes. All of theseadjectives refer to an individual or an animal which isposed in the sta lard anatomical position.
:'''+' ''
sagittal plane
In bipedal animals the standard anatomicalposition is defined as being: in the erectstance with the arms hanging vertically bythe sides, and with the face, toes, and palmsforward. See Fig. 1.
frontal plane(corona!)
In quadrupeds the standard anatomicalposition is arbitrarily defined as being: allfour feet on the ground with the head up andfacing forward. See Fig. 2.
ANATOMICAL
superior = above
inferior = below
horizontal plane(transverse)
anterior = in frontposterior = in back
proximal = nearest the center or point o'attachmentdistal = farthest from the center or point ofattachment
medial = midline or nearer the middlelateral = to the side
ventral = belly side or surfacedorsal = back side or surface
cephalic (cranial) = head areacaudal = tail area
ANATOMICAL PLANES
Anatomical planes are like imaginary panesof glass slicing through the body in a pre-cisely defined three dimensional direction.
lateral
Fig. 1 - Biped in Anatomical Position
The definitions are as follows:sagittal - a vertical plane through the longaxis that divides the body into right and left(but not necessarily equal halves).
frontal - a plane parallel with the long axisand at right angles to the sagittal; it separatesventral from dorsal.
Lecture Notes Part I 110 Introduction
horizontal - a plane which isparallel to the horizon.
coronal - a plane that sepa-rates anterior from posterior.
transverse - a plane that cutsthrough the body at rightangles to the long axis. Atransverse cut through a bodyor body part is also called across section (abbreviatedx.s.).
longitudinal - any plane orcut parallel to the long axis. Itcould be a sagittal section or afrontal section, or anything inbetween. A longitudinalsection is often abbreviated" I.s.".
frontal plane(horizontal)
corona! plane(transverse)
sagittal plane
posterior
anterior 4
Fig. 2- Quadruped in Anatomical Position
Study Figures 1 and 2 and notic,?, that forbipeds the frontal plane is also a coronalplane, while for quadru-peds the frontalplane is synonymous with the horizontalplane.
Likewise notice that for bipeds the trans-verse plane is also horizontal, while forquadrupeds the transverse plane is synony-mous with the coronal plane.
TORSO REGIONS
Study Figure 3 and notice the followingregions of the torso:
umbilicalepigastrichypogastriclumbaringuinal (iliac)hypochondriac
T 12
epigastric
fl%9
umbilical
hypogastric
hypocho
driac
lumbar
inguinal
Fig. 3- Regions of the Torso
11Lecture Notes Part I 2 Introductioo
Study Figure 4 and notice the followingcavities:
thoracic (chest)abdominalpelviccranialspinal (vertebral)buccal (mouth)nasal
cranial
nasal
buccal
vertebral
thoracic
diaphragm
abdominal
pelvic inlet
Fig. 4- Body Cavities
Lecture Notes Part 1 3
viscera - the organs of a cavity
parletes - the walls of a cavity
peritoneum - the membrane lining theabdominal and pelvic cavities and reflectedover the viscera of those cavities. Becausethe membrane is reflected, the peritoneumhasboth a parietal portion and a visceralportion.
pleura - the membrane lining the thoraciccavity and reflected over thc, surface of thelungs. Thus there is both a parietal pleuraand a visceral pleura.
cells - the building bin ks of the body.
tissues - groups of cells with similar func-tions. The four basic tissues are: epithelial,connective, muscle and nerve.
organs - architectural arrangements oftissues functioning together for a commonpurpose. Most organs are made of all fourtissues, but the tissues are arranged inrecognizably different patterns and in differ-ent proportions in the various organs.
systems- The organs are grouped togetherinto functional units called systems, such asthe digestive system', the endocrine system,the reproductive systems, the cardiovascularsystem, etc.
12 Introduction
BONE TERMINOLOGY
EPIPHYSIS:end area of a long bone
DIAPHYSIS:
center shaft of a long bone
CANCELLOUS BONE:
spongy bone; having a latticework ar-chitecture
COMPACT BONE:
solid layers of dense ivory like bone
SPICULES:a needle like fragment (in cancellous bone)
MEDULLARY CAVITY:
hollow area of the diaphysis
YELLOW MARROW:
mostly fat; fills the medullary cavity in adultbones
RED MARROW:
hemopoietic tissue. In the adult it is found inthe proximal epiphysis of the femur andhumerus, and in the cancellous interior ofshort bones, vertebral bodies, and flat bonessuch as the sternum and cranial vault.
HEMOPOIETIC TISSUE:
blood forming tissue (forms red blood cells,platelets, and certain kinds of white bloodcells)
OSTEOID TISSUE:
protein component of bone tissue (nonmin-eralized)
PERIOSTEUM:
connective tissue membrane covering bones(except in the areas occupied by articularcartilage); well vascularized, contain:. os-teoblasts and blood vessels. Some of theconnective tissue fibers (Sharpey's fibers)
111111Mt.
penetrate into the bone; Some of the bloodvessels from the periosteum penetrate thebone by way of nutrient foramena andVolkman's canals.
PERICHONDRIUM:
connective tissue membrane coveringcartilage; otherwise similar to periosteum
OSTEOBLAST:bone forming cell
OSTEOCYTE:resting bone cell
OSTEOCLAST:
bone removing cell
CHONDROBLAST:
cartilage forming cell
CHONDROCYTE:resting or mature cartilage cell
EPIPHYSEAL PLATE:
The zone of cartilage between the epiphysisand the diaphysis in a growing bone longbone
INTRAMEMBRANOUS OSSIFICATION:
bone formation from a membrane model(precu
ENDOCHONDRAL OSSIFICATION:
bone formation from a cartilage model orprecursor.
Lecture Notes Part I 4
13Osteology
y`;:,:sX :,5NANV ':'
e.,1.
".tip'`
et,
OssificationN'N:.".
HYPERTROPIBC ZONE :
an area of cartilage in which the cells areenlarged, swollen and lined up in rows orstacks. Caused by poor nutrient diffusiondue to calcification of the matrix as well asother factors.
INES:swelling and bursting of cells. Can be due toany number of causes. The area so affectedis full of cellular debris and is said to benecrotic.
PERIOSTEAL BUD:
In endochondral ossification: an invasiveembryonic blood vessel which originates inthe periosteum and penetrates into the car-tilage precursor. As it enters it drags osteo-blasts with it into the interior of the carti-lage.
GROWTH HORMONE:
produced in the anterior pituitary gland;stimulates growth of cartilage, bone, and afew other tissues as well.
PITUITARY DWARFISM:
Insufficient growth hormone during child-hood, resulting chiefly in small stature.
GIANTISM:
Excess growth hormone before closure ofthe epiphyses resulting in abnormal height.
ACROMEGALY:
Excess growth hormone after closure of theepiphyses, caused by tumor of the pituitary ,and resulting in overgrowth of the flat bonesand bones of the hands and feet, as well asovergrowth of the skin,
4
8 7,4:1 A
Flat bones like the bones of the skull areformed by intramembranous ossification.These bones are first represented by littlepieces of a tough fibrous connective tissuemembrane which are rough patterns for thebone-to-be. Since these membranes are wellvascularized and thin, osteoblast activitystarts in the center of the membrane andlayers of compact bone are formed.
Ossification is not complete at birth. Themembranes still grow , the fontanels stayopen until approximately 18 months of age,and the sutures do not close completely untilapproximately 8 years of age. . Ry this agealso the bone has been remodeled by osteo-clast activity in the center of the diploeactivity to make it light but still structurallystrong (cancellous or spongy bone), and tomake more room for the marrow.
Endochondral ossification begins with acartilage model of the future bone, This isthe method of ossification used for all of thebones except the flat bones; the long bonesOf the body serve as a good example
BACKGROUND INFORMATION:
Development of bone from a cartilageprecursor is a dynamic process. To under-stand the process, one must first understandthat cartilage is avascular, i. e. it does notcontain blood vessels. In fact healthy carti-lage contains a chemical which acts as anactive inhibitor of blood vessel growth. Asa result cartilage cells must obtain their
Lecture Notes Part 1 5 Osteology
14
nutrients by diffusion from the blood ves-sels located in the perichondrium. (Peri-chondrium is the term for the connectivetissue membrane surrounding a piece ofcartilage). In contrast to this, bone is highlyvascularized, and bone growth will not oc-cur unless there is a rich blood supply.
Secondly, one must understand that there areosteoblasts in the perichondrium. Thus acollar of bone will begin to be depositedunder the perichondrium around the outsideof the cartilage model , and the surroundingmembrane could then just as well be called aperiosteum. You will find that writers willuse the terms perichondrium and periosteumloosely and interchangeably in this situation.
Third, healthy cartilage is a growing tissue.Thus, cartilage models of future bones willtend to grow larger in size cver time, both inlength and diameter.
HE OSSIFICATION PROCESS]
Turning now to a description of the se-quence of events in endochondral ossifica-tion, and the causes of these events.
As the cartilage model enlarges diffusion ofnutrients to the cells in the center of thecartilage model is compromised due to threefactors:
a. the nutrient supply line gets too long,i. e. the distance between the cells in thecenter of the cartilage and their source ofnutrients (blood vessels in the perichon-drium) becomes so great that diffusion tothe the central cells is too slow.
b. the collar of bone deposited aroundthe cartilage model slows diffusion andputs the cells in the center of the cartilageat the greatest risk of not getting suffi-cient nutrients.
Lecture Notes Part I 6
c. Old cartilage tends to calcify and calci-fication slows diffusion.
All three of these events cause the interiorcartilage cells to be deprived of nutrients.The distressed cells hypertrophy and thenlyre. The interior of the cartilage model thusbecomes necrotic and is no longer capableof producing the inhibitor chemical whichkeeps blood vessels out of the cartilage.
As a result a blood vessel from the perichon-drium invades into the necrotic center of thecartilage model. The blood vessel is called aperiosteal bud. It drags osteoblasts fromthe perichondrium in with it, and the osteo-blasts settle down on the bits of calcifieddebris and start depositing osteoid tissue.Osteoid tissue is a protein material that isnot yet mineralized. It is deposited in theform of spicules, that is, small spines orneedles of bone that interlace with oneanother in the typical pattern seen in spengyor cancellous bone.
The area of the future bone where all thisactivity is taking place is the center portionof the shaft or diaphysis. Thus this area iscalled the diaphyseal center of ossification.The same identical sequence of steps willlater take place first in one epiphysis, andthen again, in the second epiphysis (epiphy-seal centers of ossification).
Bone deposition spreads outward in alldirections from each center of ossification,replacing cartilage as it goes. In time therewill remain only a narrow band of cartilagebetween the diaphysis and the epiphysis.This band of cartilage is called the epiphy-seal plate of cartilage.
Each long bone will have an epiphysealplate of cartilage on each end. Since thecartilage in the plates is healthy and grow-ing, the width of the epiphyseal plate isincreasing. However, at the same time, bonedeposition is encroaching from both sides
15 Osteology
(from the diaphyseal side and from theepiphyseal side), thus, the observable resultis that the epiphyseal plate tends to becomenarrower and narrower over time. It is asthough there were a race between bonegrowth and cartilage growth, and the bonegrowth is winning over the long haul.
Ossification proceeds slowly over a 20-25year period until all precursor cartilage is re-placed by bone. Eventually the epiphysealplate of cartilage is completely obliterated;this is called closure of the epiphyses, andgrowth of that bone stops. In other words,lengthwise growth of a bone is accom-plished by expansion of the epiphysealplates, and when the epiphyses close therecan no longer be expansion.
As the bone is growing it is simultaneouslybeing remodeled. A medullary cavity ishollowed out of the interior of the diaphysis,and the orientation of the bone changeswhen the stresses on the bone change. Thecells which do the remodeling are the osteo-clasts.
Bone growth is affected by many differenthormones. Among these is an anteriorpituitary hormone known as growthhormone (GH). Too much growth hormonebefore closure of the epiphyses will causegiantism. Not enough growth hormone willcause dwarfism. Too much GH after clo-sure of the epiphyses will cause acromegaly, in which the individual does not grow anytaller, but does show continued skeletalgrowth in certain of the short bones of thehands and feet, and in the flat bones of thesternum and skull and face. Thus inacromegaly the person's features becomedistorted due to over growth of some but notall aspects of the skeleton.
SEQUENCE OF EVENTS:
1. The cartilage precursor expands.
2. Diffusion is compromised in the area ofthe diaphysis.
3. Interior cells become necrotic.
4. A periosteal bud invades.
5. Bone is deposited in the interior of thediaphysis.
6. These same steps are repeated in eachepiphysis.
7. The epiphyseal plates close, and growthstops.
CAUSE/EFFECT:
1. Diffusion: Three factors interfere withdiffusion of nutrients to the cartilage precur-sor:
a. A the diameter of the model increasesthe cartilage cells in the center get too farfrom the source of supply.b. The periosteal collar of bone acts as abarrier to diffusion.c. Old cartilage matrix calcifies.
2. Necrosis: When cartilage cells are de-prived of nourishment they will hypertrophy(swell), arrange themselves in rows, andthen lyse (burst apart and die).
3. Periosteal Bud: Dying cartilage cells nolonger produce chemical inhibitors to keepblood vessels out, therefore the periostealbud enters.
4. Interior Ossification: The invading peri-°steal bud drags with it osteoblasts from the
Lecture Notes Part I 7 Osteology
16
periosteum, thus ossification can begin inth,.... interior.
5. Epiphyseal Plate: The epiphyseal anddiaphyseal centers of ossification expandtoward one another. The zone of growingcartilage remaining between them is calledthe epiphyseal plate.
6. Closure of the epiphyses occurs becausethe growth rate of cartilage in the epinhysealplate Is slower than the rate at which it isbeing replaced by bone on both edges. Theresult is :hat solid bone eventually replacesthe epiphyseal plate of cartilage. and growthstops.
Lecture Notes Part 1 8 17 Osteology
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FLEXION:
Flexion decreases the angle between twobones (brings 2 bones closer together).
EXTENSION:
Extension increases the angle between twoibones (moves 2 bones farther apart).
There are several special cases of flexion/extension:
HANDDorsiflexion (true extension)Palmar flexion (true flexion)
FOOTDorsiflexion (true flexion)Plantar flexion (true extension)
SHOULDER & HIPThe ball and socket joints of the shoulderand hip move so freely that the defini-tions of flexion and extension need to bebroadened. In these locations the defini-tion of flexion is any movement in ananterior direction and extension is anymovement in a posterior direction.
ABDUCTION:
Abduction is movement away from themidsagittal axis of the body or the centralaxis of a part. Examples: abduction of thearm; abduction of the fingers.
ADDUCTION:
Opposite of the above
ROTATION:
Rotation is movement of a body part aroundan axis or pivot point. Rotation is basicallyeither medial rotation or lateral rotation.There are several special cases of rotation.
HAND:supinationproration
Lecture Notes Part I
FOOTeversioninversion
CIRCUMDUCTION:
Technically circumduction involves flexion,abduction, extension, and adduction in thatsequence, as when the arm describes a cone.
x4,
' -.::- t..;;,'k '4 -s- ...; \:->:*. ''Ki'..:.,,*:,,i, :..U. '...W..:::-`s.is.i.
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BURSAEA bursa is a closed sac lined with synovialmembrane found where soft tissues press onbone during movement. Examples: subdel-toid bursa; olecranon bursa.
TENDON Sh2ATHESA tendon sheath is a closed synovial saclying between a tendon and a bone, protect-ing the tendon as it moves against the bone,especially when held close to the bone by aconnective tissue retinoculum. Example: thehand and the foot each contain many tendonsheaths as well as several retinacula. Ten-dosynivitis is a condition in which thetendon sheath is inflamed and tender.
10 19 Arthrology
Specific Joint Features
The shoulder joint has little anatomicalstability because the glenoid fossa is soshallow. Thus the shoulder is frequentlydislocated. The joint capsule attaches to therim of the glenoid fossa, and to the ana-tomical neck of the humerus.
MUSCULOTENDONOUS CUFF:TN, muscles surrounding the shoulder jointgive it most of its strength. The tendons offour of these muscles attach to the greaterand lesser tubercles of the humerus, forminga cuff around the anatomical head. This cuffgroup will be emphasized during the unit onmuscles.
is a common jomt cavity forthe lungejoint between the ulna and the humerus, andfor the pivot joint between the head of theradius and the ulna.
COLLATERAL LIGAMENTS:The most unusual one is the annular liga-ment which embraces the head of the radiusand within which the radius rotates freelyfor pronation and supination. See Figs. 6, 7, 8.
Fig. 6- Right Elbow Joint, Anterior Vim
Lecture Notes Part I
Strong medial and lateral collateral liga-ments strengthen the hinge joint. Theseligaments can also be called the ulnar andradial collateral ligaments.
Fig. 7- Right Elbow Joint, Lateral View
Fig. 80- Right Elbow Joint, MedialViewshowing medial collateral ligaments
The head and neck of the femur are entirelyenclosed in the joint capsule. Inside the jointis the ligamentum teres (also called liga-mentum capitis) which is attached to thefovea capitis of the head of the femur. Theligamentum teres does not hold the joint
11
20A rth rdIOLV
together, in fact it bears no strain at all,rather it provides safe passage for the vessels and nerves supplying the head of thefemur. See Figs. 9.10.
Fig, 9- Right Hipiloint Fontal Section
.t:ImmirmtvAN.,
COLLATERAL LIGAMENTS:The strongest reinforcement is anteriorly.The iliofemoral is the most important.
antrzior iliofemoralligament
joint capsule
Fig. 10- Right Hiputoint, AnteriorView
The following ligaments are the most impor-tant ones in the sacral region:
SacroliliacSacrospinousSacrotuberous
sacmspinous
sacrotuberous
Fig. 11- Sacral Ligaments, Medial View Fig. 12- Sacral Ligaments, Medial View
Lecture Notes Part I 12 Arthrology
21
The patellar tendon or ligament is part ofthe tendon from the quadriceps femorismuscle of the anterior thigh. The patellachanges the angle of pull of this tendon. It isa gliding joint. Notice that there is no articu-lation between the patella and the tibia.
k,. k
One of the most interesting features of theknee joint is that it contains severalintracapsular ligaments, the most importantof which are the cruciate ligaments. There isan anterior eradiate and a posterior crud-ate. They connect the condyles of the femurto the opposite condyles of the tibia. Thereare also several other menisco-femoral liga-ments.
Fig. 13- Right Knee, Anterior View
The knee joint has great weight bearingcapacity and considerable stability It'sstablility is largely due to the presence ofhalfmoon shaped menisci (seminar carti-lages). These cartilages are thicker on theiroutside edges and much thinner on their me-dial borders, thus both surfaces are concave.
Lecture Notes Part I
tibial tuberosity
medialmeniscus
anterior cruciateligament
lateralmeniscus
medialcollateral ligament
posterior cruciate ligament
lateralcollateralligament
Fig. 14- Right Knee, SuperiorView
COLLATERAL LIGAMENTS:The medial and lateral collateral ligamentscan also be called the tibial and fibularcollateral ligaments. They strengthen thejoint capsule, but probably the most impor-tant source of additional strength and stabil-ity are the muscles and fascia of the thighwhich extend down to the knee.
posteriormedial cruciate
meniscus
anteriorciate
menisco-femoralligament lateral
meniscus
medialcollateralligament
tibia
lateralcollateralligament
Fig. 15- Right Knee, Posterior View
13 Arthrology
22
Mostly Flexion/Extension. The weightshifts back for flexion and forward forextension.
There is some medial and lateral rotation.Locking the Knee refers to shifting forwardto full extension plus a slight amount ofmedial rotation. The locked knee providesgreat stability.
In spite of it's stability, the knee is quiteprone to injury, especially when in theextended and fully weight bearing position.Damage to a meniscus is common, espe-cially the medial meniscus since it is at-tached to the tibial collateral ligament, and ifthe ligament is torn it will often damage themeniscus as well.
Most injury to the knee is the result ofbody-contact sports, but it can also happenin running if something causes the runner toturn an ankle (eversion of the foot oftenresults in lateral flexion of the knee, whichstresses the medial ligaments and the vulner-able medial meniscus).
MOST COMMON FRACTURES:
Adduction FractureAbduction FractureCompression FractureFracture of the Tibial Spine
Lecture Notes Part I 14 '23 Arthrology
Gross Anatomy of Muscles
The three attributes of a muscle that areusually emphasized in a lecture and inreference books are action, mien, and in-sertion. Of these three the most importantattribute is action.
ORIGIN & INSERTION
The origin of a muscle is the stationary end.The insertion is the end which is mostmoveable.
As a muscle shortens the insertion is pulledtoward the origin, and the action is move-ment at whatever joints the muscle crosses.There are three ways to name the action: bythe joint name, by the body part name, or bythe name of the bone. For example: flexionof the hip = flexion of the thigh = flexion ofthe femur.
The origin and insertion are sometimesinterchangeable, depending on which end isbeing held still by other muscles or bygravity. For example, rectus abdominis cancause anterior flexion at the waist in differ-ent ways, depending on whether you arestanding, or hanging by your arms from abar, or lying on your back and bringing yourhips up toward your head.
A muscle may have two or more origins.This multiple head arrangement gives amuscle more power while still concentratingfull force on a single spot. Example: bicepsbrachii or quadriceps femoris.
A muscle may have two or more inser-tions. This arrangement spreads the actionover several joints. Example: extensors andflexors of the digits.
Lecture Notes Part I
The origin of a muscle is often attacheddirectly to the periosteum of a bone, withoutany tendon. The insertion is usually by wayof a tendon. However some muscles havetendons on both ends.
Most tendons are shaped like cords orstraps. However some muscles have a thinaponeurosis, which is actually a broadflattened sheet-like tendon connectingmuscle to muscle or muscle to bone.Examples: aponeurosis of the externalabdominal oblique and latissimus dorsi.
Tendons connect muscle to bone, whereasligaments connect bone to bone.
ACTION
The action of a muscle refers to the kind ofmovement that a muscle causes at a joint.
Muscles do work only when they contractor shorten. Stretching is passive and doesnot do work.
The prime mover is the primary agentcausing any given movement.
A synergist is a muscle which helps theprime mover in some way. It may stabilizethe origin or it may cause the same action onthe same joint as the prime mover.
An antagonist is a muscle whose move-ment counteracts the action of any givensides of a joint from one another. When theprime mover is contracting the antagonistmust relax. prime mover. Antagonists are onopposite sides of a joint from one another.When the prime mover is contracting the an-tagonist must relax.
15 Muscular System
4
Muscles of the HeadThe muscles o; the head a.: divided into two groups based on common characteristics within thegroup. These two groups are the muscles of facial expression and the muscles of mastication.
.%
Fig. 16- Muscles of Facial Expressionand Mastication
1. frontons2. orbicularis oculi3. nouli.s4. zygomaticus major5. orbicularis oris6. depressor labii inferioris
7. mentalis8. depressor anguli oris9. buccinator10. sternocleidomastoid11. masseter12. trapezius13. temporalis
MUSCLES OF FACIAL EXPRESSION
The muscles of facial expression are uniquein that they insert skin rather than onbone. They are used for nonverbal communi-cation. All of the muscles of this group areinnervated by Cranial Nerve VII, the FacialNerve.
OCCIPITAL'S
I: skin in occipital regionA: wrinkles scalp in occipital regionSee Fig. IS.
Fig. 17- Some Muscles of FacialExpression
sternocleido-mastoid
superiornuchal line
splenius capitis
trapezius
Fig. 18- Occipitalis
FRONTAL'S
I: forehead at eyebrow levelA: eyebrow flash greetingSee Figs. 16, 17.
PROCERUS
I: area between inner corner of eyebrowsA: horizontal folds between eyebrows as infrowningSee Fig. 17.
Lecture Notes Part I 16 Muscular System1Z5
CORRUGATORI: inner corner or eyebrow from diagonalangle above eyebrowA: vertical folds above inner corner of eyeas in frowningSee Fig. 17.
ORBICULAR'S ()CUL'I: surrounds eye like a sphincterA: squinting as when light is brightSet Figs. 16, 17.
NASAL'SI: bridge of noseA: wrinkles skin over bridge of nose as indisgustSee Fig. 17.
LEVATOR (QUADRATUS j LABII SUPERIORIS
0: 3 or 4 separate slips of muscleI: upper lipA: pulls lip out and up as in kissingSee Fig. 16.
LEVATOR ANGULI ORIS
I: corner of mouth, from aboveA: lifts corner of mouth as in smilingNot illustrated.
ZYGOMAT1CUS MAJOR
0: zygomatic boneI: corner of the mouthA: lifts corner of mouth as in broad smileSee Figs. 16, 17.
RISORIUS
I: corner of mouth from horizontal angleA: slightly lifts corner of mouth as in faintsmile. See Fig 17.
ORBICULAR'S ORISI: all around mouth like a sphincterA: puckering of mouth as in kissing orpensiveness or indicatingdisapproval. See Figs. 16, 11.
DEPRESSOR ANGULI ORISI: corner of mouth from belowA: pulls corner of mouth down as in griefand sadnessSee Figs. 16, 17.
Lecture Notes Part I
DEPRESSOR LABII INFE'llORISI: all along lower lip, from belowA: pulls lip down as in grief or a poutSee Figs. 16, 17.
MENTAL'S
I: point of chinA: wrinkles skin over chin as in grief, poutSee Fig 16.
BUCCINATOR
This is the deep muscle of the cheek.A: suction. See Fig 16.
PLATYSMA
A: grimacing as in fear or griefNot illustrated.
All of the muscles in this group insert on themandible. They are all innervated by themandibular division of Cranial Nerve V, theTrigeminal Nerve. The action of all ischewing.
TEMPORAL'S
0: temporal region of skullI: coronoid process of mandibleA: chewing See Fig 16.
MASSETER
0: zygomatic archI: angle of the jawA: chewing See Fig 16.
MEDIAL PTERYGOID
0: medial pterygoid plate of sphenoid; I:medial aspect of anglt of jawA: grinding movements of chewingNot illustrated.
LATERAL PTERYGOID
0: lateral pterygoid plate of sphenoid; I:medial aspect of angle of jawA: grinding movements of chewingNot illustrated.
Muscular System
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A: extension or lateral flexion of headand neck See Figs. 18, 20, 31.
CONTENTS OF THE TRIANGLEMemorize the muscle positions in the tri-angle, from top to bottom .
SPLENIUS CAPMS0: spinous processes of cervical verte-braeI: superior nuchal line of occipitA: extension or rotation of head andneck, See Fig. 20.
LEVATOR SCAPULAE
0: transverse processes of cervicalvertebraeI: superior angle of scapulaA: shrug shoulder at extend head andneck, or lateral flexion of head andneck See Figs. 20, 31.
SCALENUS MUSCLES
Learn these (3) as having a group ori-gin, insertion and action.0: transverse processes of cervicalvertebraeI: 1st and 2ndA: deep inspiration (elevates the ribs)See Figs. 20, 21.
SCALENUS MUSCLES
These were introduced with the posteriortriangle of the neck.See Figs. 20, 21.
EXTERNAL INTERCOSTALS
0: bottom edge of the upper ribI: top edge of the lower ribThe fiber direction is diagonally downwardtoward the mid line.A: elevates the lower rib. All work togetherto raise the rib cage for inspiration See Figs.21, 27.
INTERNAL INTERCOSTALS
0: the top edge of the lower rib
Fig. 20- Posterior Triangle two Neck
scalenusposterior
scalenusrnedius brachial
plexusnerves
scalenusanterior
subclavian artery
clavicle
manubriumof sternum
Fig. 21- Scalenus Muscles
I: bottom edge of the upper ribThe fiber direction is diagonally upwardtoward the mid line.A: pulls the upper rib down. All worktogether to lower the rib cage for expirationSee Fig. 28.
Lecture Notes Part I 19 Muscular System
28
DIAPHRAGM
This dome shaped muscle is unique. All thefibers start from below and rise towards acentral tendinous area at the top of thedome.
0: very widespread, in a complete ringaround the interior wall of the torsoI: central tendon of the diaphragmA: Contraction causes the dome to flatten,which enlarges the thoracic cavity increas-ing its negative pressure and causing inspira-tion. During relaxation the diaphragm takeson its dome shape again, reducing the chestcavity and causing expiration. See Fig. 22.
sternum
Fig. 22- Diaphragm, Midsagittal View
A posture muscle is an antigravity muscle; itholds the body erect by resisting the pull ofgravity. Any muscle which acts as an exten-sor at a weight bearing joint is a posturemuscle.
The extensors of the neck (head) and spine(back) therefore qualify as posture muscles.The ones we have covered so far are:clavotrapezius, splenius capitis, andlevator scapulae. Next we will consider thedeep posture muscles of the back and neck.
Lecture Notes Part I 20
ERECTOR SPINAEspinalis,longissimus
The erecter spume group is the main posturemuscle of the spinal column. It is not neces-sary to learn the names of the muscles insmall print, instead learn the action for thegroup as a whole. See Fig. 23.
SEMISPINALIS CAPITISsemispinalis cervicissemispinalls thoracisSemispinalis capitis is the deep posturemuscles (group) of the neck. Superficialhead and neck posture muscles were consid-ered previously. See Fig 23.
superior nuchal line
erecuit; spinae
,4461k1;
.01
;31 'le 1I 6. ttin 714j IVO -
At% r tie ;ts
Fig. 23- Deep Muscles of the Back
29Muscular System
Muscles of the Posterior Abdominal Wall
PSOAS MAJOR
Most people have a psoas minor, but it isins.gmlicant and in fact is absent in about20% of the population. If present its tendonwill be seen as a flat white shinning ribbonon the anterior surfac3 of psoas majer.0: sides of the bodies of lumbar vertebraeI: lesser trochanter of the femurA: flexion of the hip or flexion of the trunkSee Fig. 24.
ILIACUS
0: iliac fossaI: lesser trochanter of the femurA: flexion of the hipSee Fig. 24.
ILIOPSOAS
The iliacus and psoas muscles startseparately, but soon their tendons fuseand have a common insertion andaction. The fused portion is called theiliopsoas muscle.See Fig. 24.
QUADRATUS LUMBORUM
0: iliac crestI: lower ribsA: lateral flexion of the trunk .
See Fig. 24.
Lecture Notes Part I
Fig. 24 Muscles of the PosteriorAbdominal Wall, Anterior View
21
3 0Muscular System
MUSCLES OF THE ANTERIOR
ABDOMINAL WALLIn addition to whatever else they do, themuscles of the anterior abdominal wall allact to compress the abdomen. Compressionof the abdomen is necessary to hold theviscera in place, and to aid in such func-tions as : forced expiration, coughing,sneezing, vomiting, defecatio-i, urination,and parturition
RECTUS ABDOMINIS MUSCLE
There are two rectus muscles. They lie nextto one another on either side of the linenalba. The fibers run vertically but are inter-
rupteii periodically by transverse fibrousbands called the tendinous inscriptions(a.k.a. tendinous interruptions; tendinousinsertions). See Fig. 25.
Sheath of the RectosSince there is nc bone to attach to in thefront of the abdomen, the aponeuroses of thethree anterior- lateral abdominal musclespass across the surface of the rectus on theirway to the midline where they meet and fusewith those of the opposite side, forming thelines alba
Because of this arrangement, the rectus iscovered by layers of connective tissueknown as the sheath of the rectos. Theprecise anatomy of these layers is importantsurgically: See Fig. 26.
the aponeurosis of external obliquepasses anterior to rectus;
the aponeurosis of the transversemuscle passes posterior to rectus;
the aponeurosis of internal obliquesplits, half passing anterior and halfposterior to the rectus.
Lecture Notes Part I 22
1. rums abdominis
2. lines alba
3. tendinous inscriptions
4. inguinal ligament
5. external inguinal ring
Fig. 25- Rectus Abdorninis
Fig. 26- Sheath of RectusI. rectus abdominis 5. tranfversus2. Linea alba 6. aponeurosis of ext. oblique3. external oblique 7. aponeurosis of int. oblique4. internal oblique 8. aponeurosis of transversus
Fiber DirectionThe antero-lateral abdominal muscles arelayered to reinforce one another. It is notnecessary to memorize the extensive originsof these lateral muscles, instead learn torecognize them by their fiber direction.
Si. Muscular System
EXTERNAL OBLIQUE MUSCLE
The fibers of external oblique run diagonallydown and toward the midline vine thedirection of your fingers when putting yourhands in the side pockets of a pair of jeans).0: widespread, but basically from theexter-nal surfaces of the lower 8 ribs.I: linea alba (and crest of ilium)A: compression of the abdomen and trunkrotation. See Fig. 27.
6. external intercostal
7. external oblique
8. aponeurosis ofexternal oblique
Fig. 27- External Oblique
INTERNAL OBLIQUE MUSCLE
The fibers of the internal oblique run diago-nally up and toward the midline.0: lateral half of inguinal ligament, iliaccrest, and lower ribs.I: linea albaA: compression of the abdomen, and trunkrotation See Fig. 28.
TRANSVEFtSUS ABDOMINIS
The fibers of transve. sus run horizontally.0 inguinal ligament, iliac crest and lowerribs. I: linea albaA: compression of the abdomen, and trunkrotation See Fig. 29.
9. internal intercostal
10. internal oblique
11. aponeurosis ofinternal oblique
Fig. 28- Internal Oblique
--wM
14
Fig. 29- Trans versus Abdominis
12. transversus13. aponeurosis14. spermatic cord
Lecture Notes Part I 23
3Muscular System
DESCENT OF THE TESTES
INGUINAL LIGAMENT
The inguinal ligament marks the dividingline where wall of abdomen stops and thighbegins. It extends from the anterior supe-rior iliac spine to the pubic tubercle, and isfanned by connective tissuethat blends withthe lower free edge of the external obliqueaponeurosis. See Figs. 25, 30.
INGUINAL CANAL & RINGS
The inguinal canal is a tunnel that passesthrough the layers of the abdominal wallgradually one by one rather than directlythrough all three at once. The internalopening of the tunnel is called the deep in-guinal ring. The superficial opening iscalled the external inguinal ring.See Figs. 25, 30.
GUBERNACULUM
The gubernaculum is an embryological con-nective tissue cord that is attached to thegonad, passes through the inguinal canal,and then attaches to the inside of the scro-tum (in the male) or labia majora (in thefemale). In the male this cord shortensshortly before birth, pulling the testicle outof the abdomen, down thru the inguinalcanal, and into the scrotum.
SPERMATIC CORD
The spermatic cord remains attached to thetesticle and therefore it occupies the inguinalcanal in the male. See Figs. 29, 30.
CRYPTORCHIDISM
Cryptorchidism means hidden testicle, and itrefers to failure of the testicle to descend.The condition is easy to correct surgically. Ifnot corredted, the adult male will be sterilebecause the temperature inside the abdomenis too high for the production of sperm cellsalthough testosterone production will not beaffected.
Lecture Notes Part I
external oblique Ilea albasheath of roc
biguinal ligament
external inguinal ring
Fig. 30- inguinal Ligament
CREMASTER MUSCLE
As the testicle descends, some of the fibersof internal oblique get hooked around thetesticle and dragged down into the scrotum.These loops of muscle are called the cremas-ter muscle. Contraction of the cremaster candraw the testicle up into the abdomen ininfants. Sumo wrestlers have been trainedsince infancy so that they retain this abilityas adults.
HERNIA
A hernia is any protrusion of an internalorgan into a cavity where it is not normallyfound.
INDIRECT HERNIA
An indirect hernia refers to protrusion ofa loop of intestine through the inguinalcanal into the scrotum. It may be causedby anything which increases abdominalpressure, and it usually only happens inmales, presumably because the inguinalcanal is somewhat more open in males.
DIRECT HERNIA
A direct hernia refers to a protrusion ofintestine through a tear in the abdominalwall. It can be caused bya blow to theabdomen, or by weakness of the abdomi-nal muscles.
24 33 Muscular System
Mooring Muscles of ScapulaThe only place in the pectoral girdle where
ligaments hold bone fo bone is between theclavicle and sternum, elsewhere onlymuscles hold the shoulder girdle in place onthe axial skeleton. The reason for thishighly unusual situation is the necessity forvery free movement of the arm.
clavotrapezius
acromiotrapezius
spinotrapezius
rhomboideus major
latissirnus dorsi
All of the muscles in this group originateon the axial skeleton and insert on thescapula. Notice that they approach thescapula from every possible direction.
superior nuchal line
levator scapulae
rhomboideus minor
rhomboideus major
serrates anterior14
external abdominal oblique
Fig. 31- Mooring Muscles of the Scapula.Superficial muscles +re shown on the left side. Deep muscles are shown on the right side.
Lecture Notes Part 1
25 4Muscular System
TRAPEZIUS
This muscle has three sections that can actseparately due to separate innervations.
clavotrapeziusac romlotrapezlusspinotrapezius
0: superior nuchal line, ligamentum nuchaeand spinous processes of all thoracic verte-braeI: clavicle, acromion, and spine of scapulaA: elevation, adduction, and depression ofscapula. Extension and lateral flexion ofhead and neck.See figs. 31, 16, 18, 20, 33.
RHOMBOIDEUS MAJOR & MINOR
0: spinous processes of thoracic vertebraeI: vertebral border of scapulaA: adduction of scapulaSee fig. 31.
LEVATOR SCAPULAE0: transverse processes of upper cervicalvertebraeI: superior angle of scapulaA: elevates scapula (shrug shoulder). Exten-sion and lateral flexion of neckSee figs. 20, 31.
SERRATUS ANTERIOR
0: front surface of ribsI: vertebral border of scapulaA: abduction (protraction) of scapula (im-portant in pushing)See figs. 31, 32, 39.
PECTORAL'S MINOR
0: front of ribsI: coracoid process of scapulaA: stabalizes scapula See fig. 33.
Lecture Notes Part I
Fig. 32- Serratus Anterior
acromiotrapezius
ac-romio-deltoid
cleidomastoid
stemomastoid
pcctoralismajor
Fig. 33- Pectoralis MinorPectoralis major has been removed.
26 Muscular System35
Muscles acting on Shoulder Joint
All of the muscles in this group originateon the axial skeleton and insert on the headof the humerus. They form a musculoten-dinous atfaround the head of the humerus,helping to hold it in its socket. They all acton the humerus.
1. s
1.-14000p--Nttriusq.
woo, inserts on anterior surface
444 4. toms major
of humerus
Fig. 34- Rotator Cuff MusclesRight Arm, Posterior View
SUPRASPINATUS0: supraspinous fossa of scapulaI: greater tubercle of humerusA: abduction of humerusSee Figs. 34, 38, 41
INFRASPINATUS0: infraspinous fossa of scapulaI: greater tubercle of humerusA: lateral rotation and extensionSee Figs. 34, 38, 41
TERES MINOR
0: axillary border of scapulaI: greater tubercle of humerusA: same as infraspinatusSee Figs. 34, 38, 41
SUBSCAPULARIS
0: subscapular fossaI: lesser tubercle of humerusA: medial rotation of humerus and extension ofhumaus See Fig. 35, 41
Fig. 35- Shoulder Girdle, Anterior View
.CL
Included in this group are the powermuscles which of the ann. They all originateon scapula and/or clavicle and insert onupper shaft of humerus.
As a rule, any muscle which is a flexor orextensor of the arm will also act as anadductor of the arm.
DELTOID
This muscle has three separate sections thatcan act separately due to separate innerva-tions:
AcromiodeltoidClavodeltoidSpinodeltoid
0: clavicle, acromion process of scapula,and spine of scapulaI: deltoid tuberosity of humerus
Lecture Notes Part I 27 Muscular System
36
A: See Fig. 33, 36, 37, 38, 39, 41.
Acromiodeltoid: abductionClavodeltoid: flexion, Aducdon,medial rotationSpinodeltoid: extension, adduction,lateral rotation
Fig. 36 -Deltoid, Anterior View
old
Fig. 37 -Deltoid, PosteriorView
TERES MAJOR
0: inferior angle. of scapula along axillaryborder.
bicipital groove (medial crest )A: same as latissimus dorsiSee Fig. 34, 38, 41.
LATISSIMUS DORSI
This muscle forms the posterior wall of theaxilla. It is flat and sheetlike; it has a wide-spread origin and a small insertion, hence it
concentrates great force on a small area0: low back vertebrae by way of the lum-bodorsal aponeurosis
bicipital groove, anterior humerusA: extension, medial rotation and adductionof humerus See Figs. 31, 41
1/4
supraspinatusinsertion /0041,"vae.se
r _Ap Pa.....cr:v Jr
Se.s.
\sscapula
deltoidinsertioninsertion
brachialisinsertion
Fig. 38- Teres Major, Posterior View
PECTORALIS MAJOR
This muscle forms the anterior wall of theaxilla. It has four overlapping heads0: clavicle, sternum and ribsI: lateral crest of the bicipital grooveA: flexion, medial rotation, adductionSee Figs. 31, 41.
clavicular head ofpectoralis major
sternal heads ofpectoralis major
1
Fig. 39- Pectoralis major
Lecture Notes Part 1 28 Muscular System37
CORACOBRACHIALIS
0: coracoid process of scapulaI: shaft of humerus,A: flexion and adduction of humerusSee Figs. 40
Fig. 40- Coracobrachialis, Anterior View
infraspinatussubscqularis
tares minor (lesser tubercle)
intertubercular groove(bicipital groove tares major
latissimuspectorals dorsimajor
Fig. 41- Major Insertions on ProximalEnd of Humerus, Anterior View
Lecture Notes Part 1 29
Muscles Acting on the Elbow JointThe flexors are on the anterior side of the
elbow; the extensors are on the posteriorside . latissimus dorsi
insertion
bicipital groove
During supination and pronation of theforearm the ulna remains stationary whilethe radius rolls over the top of the ulna. As aresult all supinator and pronator musclesmust insert on the radius.
BICEPS BRACHH
0: short head: cora-coid process ofscapula;long head: supragle-
sh"t head noid tubercle ofscapula. The tendonof this head lies inthe bicipital groove
of the humerus.biceps I: tuberosity of radiusbrachii
and ulnar aponeurosisA: flexion of el'oowand supination offorearm, also flexionat shoulderSee Figs. 41, 42, 44.
Fig. 41- Biceps brach!!Anterior View Right Arm
BRACHIALIS:
0: lower half of shaft of humerusI: coronoid process of ulna and ulnar tuber-osityA: flexion of elbowSee Fig. 42
BRACHIORADIALIS
0: lateral epicondyle of humerusI: styloid process at distal end of radiusA: flexion of the elbow and supination offorearmSee Figs. 43, 44.
teres majorinsertion
rod.11 .
Ai---040,. coracold process
it111biceps tendon
I,11. r -..: coracolvachialis
ideltoid,insertion
brachialartery
brachialis
supinat
Fig. 42- BrachialisAnterior View Right Arm
Fig. 43 Brachioradialis.Anterior View Right Arm
brachioradialis
pronatorteres
pronatorquadratus
Lecture Notes Part 1 30 Muscular System3 9
PRONATOR TERES0: medial epicondyle of humerusI: shaft of radiusA: pronation of forearm; flexion of elbowSee Figs. 43, 44.
Fig. 44- Right Elbow, Anterior View
PRONATOR QUADRATUS0: distal shaft of ulnaI: distal shaft of radiusA: pronation of forearmSee Fig. 43.
SUPINATOR
lies deep to the brachioradialis0: lateral epicondyle of humerusI: upper shaft of radiusA: supination of forearmSee Fig. 42.
TRICEPS BRACHI'three heads of origin0: long head: scapula, infraglenoid
medial head: proximal humeruslateral head: distal humerus
I: olecranon process of ulnaA: extension of elbowSee Fig. 45.
ANCONEUS
0: lateral epicondyle of humerusI: ulnaA: extension of elbowSee Figs. 45, 46.
Fig. 45- Triceps Brachii,Right Arm, Posterior View
Fig. 46- Anconeus,Right Arm, Posterior View
Muscles acting on Wrist & Finger JointsThe muscles which originate on the medial epicondyle are flexors or pronators. The muscles
which originate on the lateral epicondyle are extensors or supinators. Brachioradialis ispar-tially an exception in that its origin is the lateral epicondyle; it is a flexor & also a supinator.
Rule to follow when identifying muscles of the forearm: first identify and mentally set asidebrachioradialis and pronator teres. They do not act on the wrist or fingers.
The flexors of the wrist and fingers are on the anterior surface and generally originate on ornear the medial epicondyle of the humerus.
The extensors are posterior or lateral and originate on or near the lateral epicondyle.
The flexors and extensors of the wrist and fingers have a minor action at the elbow and you donot need to memorize it.
All of these muscles originate on themedial epicondyle of the humerus and allact to flex the wrist and elbow.
PALMARIS LONGUS
0: =dial epicondyleI: palmar aponeurosisA: flexion of wrist andelbowSee Fig. 49.
FLEXOR CARPI
ULNARIS
0: medial epi-condyleI: wrist (carpus) onlittle finger side.A: flexion of wrist andelbow and adduction ofwristSee Figs. 47, 49.
FLEXOR CARPIRADIALIS
0: medial epi-condyleI: wrist (carpus) onthumb sideA: flexion of wristand elbow andabduction of wristSee Fig. 49.
interosseousmembrane
flexor carpiulnaris
t
Fig. 47- Flexor CarpiUlnaris
Right Forearm, Anterior View
FLEXOR DIGITORUMsuperficiais &protundus0: medial epicondyleI: four fingers (not thethumb)A: flexion of fingers,wrist and elbowSee Fig. 48.
X01"
digi
interosseousmemtrane
.) 'pi 46:f..e IT }
41 el
t.
Fig. 48- Flexor DigitorumRight Forearm, Anterior View
Lecture Notes Part I 32 Muscular System4 1.
ribs
; 1.N...4 1
: 1 .....,I. 1 t li,
"..---.\,Cri ..
. ...... A.:. .....
.50'. i r.0. Ori,s..t ...r" ire*"
1 ...s 4144,Y"' go .a : 1 f
at 4C I ".: it.
F I 1 fr.4.4 median nersin
g carpal turiffel
/*radialartery
pisiformbone
flexor carpiWrath
tibiar neve,ulnar artery
1 flexor carpiradialis
palmaris longus
Fig. 49- Superficial Flexor TendonsRight Wrist
All of these muscles originate on thelateral epicondyle and all act to extend thewrist and elbow.EXTENSOR CARPI RADIAL'S LONGUS
0: lateral epidcondyleI: wrist, thumb sideA: extension and abduction of wristSee Fig. SO.
EXTENSOR CARP! RADIAL'S BREVIS
0: lateral epidcondyleI: middle of wristA: extension of wristSee Fig. 50.
EXTENSOR CARPI
ULNARIS
0: lateral epidcondyleI: wrist, little fingersideA: extension and adduc-tion of wristSee Fig. 50, 51.
Fig. 50- Superficial Extensor Tendonstendons are protected by tendon sheaths as they
pass under the extensor retinaculum
EXTENSOR DIGITORUMcommunis and indicis0: lateral epidcondyleI: all four fingers (not the thumb)A: extension of wrist and fingersSee Fig. 50.
EXTENSOR DIGITI MINIM (QUINT')
0: lateral epidcondyleI: little fingerA: extension of wrist and 5th fingerSee Fig. 50.
extensor carpi ulnaris
Fig. 51-
Extensa 'arpi UlnarisRight Forearm, Dorsal View
&En
;*--
Lecture Notes Part I 331'42
Muscular System
All the muscles in this group originate onthe radius and all insert on the thumb. Thename of the muscle indicates its action.
The tendons of extensor carpi radialislongus and brevis tunnel under the extensorsand abductor of the dumb
When the thumb is forcibly abducted andextended a hollow fossa called the anatomi-cal spud box appears at the base of thethumb. It is created by the tendons ofthosemuscles.
EXTENSOR POLLICIS LONGUSSee Fig. SO, St
EXTENSOR POLLICIS BREVISSee Fig. 50, 52.
ABDUCTOR POLLICIS LONGUS
FLEXOR POLLICIS LONGUS
extensor pollicis longus
extensor pollicis brevis
qr
on,b)
Fig. 52- Extensor Pollicis Longus & BrevisRight Forearm, Posterior View
Extensor pollicis longus is shown as transparent where it overlies Extensor pollicis brevis.
Muscles of the Hip and Thigh
The tough thick investing fascia of thelateral thigh is called the fascia lata. Part ofthis fascia is especially tough and thick andis called the iliotibial tract or iliotibialband. This band extends from the crest ofthe ilium to the lateral condyle of the tibia;it acts as a kind of tendon for two of themuscles of the gluteal group.
Fig. 53- Lateral View, Left Leg
TENSOR FASCIA LATA
0: anterior superior iliac spineI: iliotibial tractA: flexion of hip; tightens the iliotibi, tractand therefore helps brace the knee & ab luctthe legSee Fig. 53.
GLUTEUS MAXIMUS
The gluteus maximus in man is very largeand coarse and powerful since it helpsmaintain the erect posture of the trunk. It isespecially used in standing up from a sittingposition climbing stairs or hills, in deep kneebends, and in running.
Lecture Notes Part I
. i tac crest, sacrum, an. coccyxI: shaft of femur below greater trochanter, &ilio tibial tractA: extension and/or lateral rotation of thehip, also abduction of leg and bracing of theextended kneeSee Figs. 53 and 60.
GLUTEUS MEDIUS
'Mink of this muscle as homologous to thedeltoid muscle of the shoulder. It has threesections, (part 1. anterior; part 2. middle;part 3. posterior), which can act separately.0: crest of iliumI: greater trochanterA: part 1: medial rotation, flexion;
part 2: abduction;part 3: extension, lateral rotationSee Fig. 53.
GLUTEUS MINIMUS
0: posterior surface of iliumI: greater trochanterA: medial rotation and abductionNot illustrated.
DEEP GLUTEAL GROUPpisiformisgemellus superiorobturator internusgemellus inferiorobturator externusquadratus femorisLearn these as a group, not individually. Allof the muscles in the group are small, allpass behind the hip joint, all insert on thegreater trochanter, and all are lateral rota-tors of the hip. Quadratus femoris is largeand prominent in the cat. Not illustrated.
ANTERIOR THIGH
ILIOPSOAS
This muscle of the posterior abdominal wallis the main flexor of the hip.See Figs 24, 59.
35
4 4Muscular System
SARTOillUSThe Tailor's Muscle; thelongest muscle of the body inhumans. It is slender, strap-like (broad in the cat) and k4
crosses the thigh diagon-ally, crossing both the hipand the knee joints.0: anterior superior iliac spineI: proximal tibia, medial sideA: flexes thigh and knee andlaterally rotates thigh. It canraise the leg into the "tailor'sposition", hence it's name.See Figs. 54, 55, 60, 59.
QUADRICEPSFEMORISThis muscle group hasfour heads of origin.
All arise from the femur,except for the rectuswhich is from the ilium.All insert on the tibial tu-
berosity by way of a com-mon tendon (the patellartendon). Thepatella adds lev-erage to improvethe angle of pullon the tibia.
All extend thetibia; in additionthe rectus helpsflex the thigh.
All are impor-tant in walking,running, climb-ing, junping, andkicking. Therectus is espe-cially importantin kicking.
?At7.11.,n.
tibial
Fig. 54 SartoriusRight Leg
RECTUS FEMORIS0: iliumI: tibial tuberosityA: extension of tibia,fIbxion of hipSee Figs 5S, 56.
VASTUS INTERMEDIUS
This muscle lies deep torectus femoris. It is notillustrated.0: femurI; tibial tuberosityA: extension of tibiaNot illustrated.
VASTUS LATERALIS
0: femurI: tibial tuberosityA: extension of tibiaSee Figs 55,58.
VASTUS MEDIAL'S
0: femurI: tibial tuberosityA: extension of tibiaSee Figs 55, 57.
Fig. 55 Anterior Thigh, Right Leg
4
Fig. 56- RectusFemoris
Fig. 57- VastusMedialisRight Leg
Lecture Notes Part I 36
45Muscular System
vastuslateral's
Fig. 58- Vastus Lateral's & GracilisRight Leg
- si
All are adductorsAll originate from the pubis and/or ischiumAll except gracilis insert on linea aspera.
IL..
adductor brevis
pectineus \\ssi""".%!
ea.
adductor longus
adductor magna
iRT
vai Linea aspera
k7i=
gluteusmaximus
Fig. 59- Adductor InsertionsPosterior view of right thigh, hamstrings removed.
4%1-1
Fig. 60. Adductor Longus & PectineusAnterior view of right thigh.
GRACIUSGraceful, slender, strap- like.in humans(broad in the cat).0: pubisI: proximal tibia, medial sideA: adduction of femur, braces the knee, alsoflexion of hip and knee See Figs. 55 and SS.
ADDUCTOR MAGNUS0: pubis & ischiumI: linea asperaA: adduction of femur, also flexion, lateralrotation, and extension of femur See Fig. 60.
ADDUCTOR LONGUS
0: pubisI: linea asperaA: adduction of femur, also flexion and lateralrotation of femur See Figs. 55, 59, 60.
ADDUCTOR BREVIS
0: pubis & ischiumI: linea asperaA: adduction of femur, also flexion and lateralrotation of femur See Fig. 60.
PECTINEUS
0: pubisI: linea asperaA: adduction of femur, also flexion and lateralrotation of femur See Figs. 55, 59, 60.
Lecture Notes Part I 37/46
Muscular System
All originate from ischial tuberosity.All insert on the lower leg.All extend the thigh and flex the knee; they
are important in walking.All rotate the leg.All brace the knee.
Fig. 61- Hamstring insertionsPosterior View of Right Knee
BICEPS FEMORIS
0: two heads of origin,long head: ischial tuberosity,'tort head: linfta aspera of femur
I: proximal fibula, lateral sideA: extension of hip, flexion of knee, andlateral rotation of leg See Figs. 61 and 62.
SEMIMEMBRANOSUS0: ischial tuberosityI: proximal tibia, medial sideA: extension of hip, flexion of knee, andmedial rotation of legSee Figs. 61 and 63.
SEMITENDINOSUS0: ischial tuberosityI: proximal tibia, medial sideA: extension of hip, flexion of knee, andmedial rotation of legSee Figs. 61 and 64.
',MAO
long headbiceps femoris
short head
i.s 1 4#\)I. leire....* 11:0110.P,
biceps fentoris t. r
.4. I ,.....,...*w.'r1
Fig. 63-
SenimeinbranosusPosterior View,
Right Leg
ischialtuberosity
1.,ele 4N e.
4 a'. .;
Fig. 62- Biceps
FemorisPosterior View,
Right Leg
tree' ay
Fig 64 -
SemitendinosusPosterior View,
Right Leg
Lecture Notes Part I 38 47 Muscular System
\-',,,`*--',.-:-.,'',.:1.:".,.-,--",-:==-='-'-,k.;c.: ..?:.....,-...-,- - -.:.z.--.;4 ; ,,.:...:::',...A }.,, .1 ir i f ,..,,, I ., , , ,,, ...ir ..,
-',.? . . I '..1':. '.., ,;, `,::,:!:: s\e,..i\\'` S., ,\ .,: '1... ..:`, , -`, ,,, ,..,-, '...., , ::, .q. is'f
41.
PERONEUS TERTI
I I I 0 LI1 f r, I. 0,1_1' I I I I
I I I I 1111 I I, 1..I . I I
I I I I 0 ' I ' I I I'I I I I I
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00So
.
00
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I
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.1 I I I II I 'I' I
t
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: M
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PERONEUS BREVIS0: fibula and intezosseus membraneI: base of the 5th metatarsalA: plantar flexion and eversion of footFigs. 66 and 67.
Fig. 66- AnteriorView of Right FootShowing common insertion for tibialis anterior and
peroneus longus.
These are the calf muscles.Gastrocnemius , soleus,and plantaris have acommon tendon of inser-tion, the tendocalcaneus(Achilles' tendon),which inserts on thecalcaneus and raisesthe heel.
GASTROCNEMIUS
0: two heads of origin,the medial and lateral epi-condyles of the femurI: calcaneusA: flexion of knee and ex-tension (plantar flexion)of ankleSee Figs. 70 and 61.
Ere.
.3
$
iLti
10
Fig. 68- GastrocnemiusRight Calf Posterior View
plantaris
astrocnendus
tendocalcaneus
SOLEUS0: tibia and fibulaI: calcaneusA: extension (plantarflexion) of ankleSee Fig. 69.
PLANTARIS
In humans this is asmall muscle with avery long tendon.0: lateral epicondyleof femurI: calcaneusA: extension (plantar flexion)of ankle and flexion of kneeSee Fig. 69.
POPLITEUS
This small muscle isconfined to the floorof the popliteal fossa.0: femur, lateralcondyleI: tibia, medial sideA: rotates lower leg medially to unlock theknee jointSee Fig. 61.
1,:s
Fig. 69- Saws andPlantaris
Right Calf Posterior View,Gastrocnemius Removed
The tendons of thisgroup pass behind themedial malleolus. Theyall plantar flex (extend)and invert the foot.
TIBIALIS POSTERIOR
0: tibia, fibula, andinterosseous membraneI: tarsusA: plantar flexion &inversion of footSee Figs. 70, 73, and it
Fig. 70- Tibialis PosteriorRight Leg, Posterior View
Lecture Notes Part I 40 4 9 Muscular System
FLEXOR DIGITORUM
LONGUS
0: tibiaL four toesA: flexion of the toes,as well as plantarflexion & inver-sion of footSee Figs. 71, 73, 74. flexor
digitorum
t"4
ti
membrane
Fig. 71- Flexor DigitorumRight Leg, Posterior View
FLEXOR HALWCIS
LONGUS
The tendon liesclosest to the bone.0: fibula
great toeA: flexion of the bigtoe as well as plantarflexion & inversionof footSee Figs. 72, 73, and 74.
Fig. 71- FlexorHallucis Longo
Right Leg, Posterior View
tibialisposterior
medialmalleolus
.tt4 Achilles
1:"4: :47' tendon
"Al #a.t .;" flexor
.Atr..::ts's digitoruVo$1..q
flexorhallucistongus
Fig. 73- Tendons of Deep Calf MusclesRight Foot, Medial View
Lecture Notes Part I
Fig. 74-A
Fig. 74-B
Fig. 74 A & B- Insertions of the DeepCalf Muscles. Figure 74A is less detailedthan Figure 748. Right Foot, Ventral V.ew
41 Muscular System
5 0
intermediate massof thalamus
parieto-occipital/ fissure
calcarinefissure
IVthventricle
inferior cerebellar peduncle
Fig. 76- Human Brain In Sagittal Section
Lecture Notes Part I 42 Nervous System
Introduction to Nervous SystemBasic Terminology and Basic Concepts\ k, `$
NEURONS
cell bodydendriteaxon
NEUROGLIA
Schwann cellsoligodendrogliaastrogliamicroglia
EPENDYMAL CELLS
M'RaM.A*21.
boutons terminaux;synaptic vesicles;synaptic cleft;presynaptic membranepost synaptic membrane;receptor sitestransmitter esterasemotor end plate
NEUROTRANS MITTERS.
FACILITATORS:
AcetylcholineAdrenalinEpinephrineNorepinephrine
INHIBITORS:
SerotoninDopamineGABA
THE NERVE IMPULSE:
A nerve impulse is a traveling membranedepolarization.
Lecture Notes Part I
MYELINATION
myelinnodes of RanvierneurilemmaSchwann cells"Jelly Roll Theory of myelin formation"regenerationunmyelinated nerves;
OTHER COVERINGS:
endoneuriumperineuriumepineunum
.,
..
Gray matter areas are regions where cellbodies and dendrites predominate. The im-plication is that synapses are made here.Masses of gray matter are called:
cortexnucleiganglia
or by individual names such as:oliveamygdalahippocampushypothalamusthalamus
NUCLEUS:
A group of nerve cell bodies within theCNS; no connective tissue boundaries.
GANGLION:A group of nerve cell bodies outside theCNS; encapsulated by connective tissue.
CORTEX:
A surface layer of gray matter (about 114inch thick) found on the cerebrum andcerebellum.
4352
Nervous System
White matter areas are regions where myelinis predominante. The implication is thataxons are passing thru\ough the area inlarge numbers. Masses of white matter arecalled by such names as:
tractsnervesconarnissurespathwaysfasciculicorona radiata
TRACTS:
Bundles of axons traveling within the CNS;not covered with connective tissue wrap-pings.
ascending or afferent tracts (sensory)descending or efferent tracts (motor)Commissures
NERVES:
Bundles of axons traveling outside the CNS;covered with connective tissue wrappings.Some nerves are afferent and some areefferent.
Lecture Notes Part I 44 or 3 Nervous System
Spinal Cord Anatomy & Spinal Nerves
dorsal white column(funiculus)
dorsal median septum
dorsal root of spinal nerve
dorsal rootganglion
dorsal ltom
dorsal whitecornmissure
central canal
ventral whiteconunk sure
ventral whitecolt=
ventral median sulcus
mixed spinal nerve
ventral root of spinal nave
Fig. 77- Diagram of Spinal Cord in Cross Section
;s ;::;v''-.,
SENSORY NERVESDORSAL ROOT GANGLION CELLS
The receptor of a sensory nerve resides inthe periphery of the body, the axon synapseswith a nerve cell in the gray matter of thespinal cord, and the cell body resides outsideof the cord in the dorsal root ganglion.
INTERNUNCIAL NERVESThe cell body, axon, and synapse of aninternuncial neuron all lie entirely within thespinal cord.
MOTOR NERVES:ANTERIOR HORN CELLS:
Anterior horn cells are the cell bodies ofmotor neurons which synapses with skeletalmuscle cells.
LATERAL HORN CELLS:
Lateral horn cells are the cell bodies of auto-nomic nervous system motor neurons thatsynapse with cells in ANS ganglia. Lateralhorn cells are also called preganglionicmotor neurons. (Postganglionic neurons arethose which start in the ganglia and synapsewith smooth muscle, cardiac muscle, orgland cells.)
SPINAL CORD TERMINOLOGY
Cervical Enlargement;Brachial Plexus;Lumbar Enlargement,Lumbosacral Plexus;Conus Medullaris;Cauda Equina;Filum Terminale;
Lecture Notes Part 1 45 Nervous Systemi4
There are 8 pairs ofcervical nerves, 12 pairsof thoracic nerves, 5 pairsof lumbar nerves, and 5pairs of sacral nerves,and 1pair of coccygealnerves. The roots of thesenerves often combine incomplex patterns to formplexuses (networks). Thereare four important plexuses:
C1- C4. roots ofcervical plexus
C S - Tl, roots ofbrachial plexus
ChRVICAL PLEXUS: C1-C4C 1-3 supply the muscles and
skin of theneck and shoulder .
thoracicnerves
There is one major nervefrom the cervical plexus Li - S3, cauda
equina (roots oflumbosacral
plexus)
(mostly C4):
PHREN1C NERVE
supplies the diaphragm
BRACHIAL PLEXUS: C5-C8 AND T1
Some branches from this plexus supply themuscles and skin of the shouldergirdle.
cervicalenlargement
lumbarenlargement
conusmedularis
There are four majornerves from the brachialplexus that supply the skinand muscles of the arm.They are named and dis-tributed as follows:
filum terminate
RADIAL NERVE :
extensors of both armand forearm
MUSCULOCUTANEOJSNERVE :
flexors of upper arm
MEDIAN NERVE :
flexors of forearm,thumb side
ULNAR NERVE :
flexors of forearm,little finger side
Fig. 78- Diagram of Human Spinal Cord& Spinal Nerve Roots
Longitudinal View
CI
to neck C2
muscles C3
CN XI
phrenic nerve
Cr.;
to brachialplexus
toshoulder
4 muscles
Fig. 79- Distribution of Cervical PlexusLeft Arm, Anterior View.
Lecture Notes Part I 46
Fig. 80- Distribution of Brachial PlexusI. radial nerve 2. musculocutaneous nerve
3. median nerve 4. ulnar nerve
55
THORACIC NERVES : TJ12The thoracic nerves (except for Ti) do notform a plexus, they simply become the:
INT ERCOSTAL NERVES.
LUMBOSACRAL PLEXUS:The lumbosacral plexus is divided into twosubsections, the lumbar plexus and thesacral plexus.
LUMBAR PLEXUS: I.,- L.
FEMORAL NERVE:
anterior thigh muscles and skin (quadri-ceps, iliopsoas, and sartorius).
OBTURATOR NERVE:
gracing, adductor longus, and adductorbrevis
SACRAL PLEXUS: L4 eS3)
SCIATIC NERVE
tibial and peroneal branches. Suppliesgluteal region; adductor magnus; poste-rior thigh and all of leg and foot. Safegluteal quadrant.
PUDENDAL NERVE:
sensory and motor to the genitalia, pelvicorgans and pelvic muscles.
Lecture Notes Part I 47 Nervous System
4.)
AUTONOMIC NERVOUS SYSTEMThere are two divisions of the ANS: sympa-thetic and parasympathetic. The two divi-?ins have some things in common and theyhave some differences.
EFFECTOR ORGANS:
One important similarity is that both divi-sions supply the same effector organs,namely smooth muscle, cardiac muscle, andgland.
GANGLIA:
A second similarity is that both divisions useganglia. However the ganglia have verydifferent locations in the two divisions
MOTOR SUPPLY:
A third important feature shared by bothdivisions is that motor supply to the, effectororgan requires two motor nerves. The first ofthese nerves is termed a preganglionicneuron since it starts in the CNS and ends ata ganglion. The second of these nerves istermed a postganglionic neuron since itstarts in the ganglion and goes to the effec-tor.
GANGLION LOCATION:
PARAVERTEBRAL:
These are sympathetic ganglia. There are 22of them on each side of the body. They arelocated next to the vertebral column, and areconnected to one another in a chain likeformation, hence: paravertebral chain. Theterm sympathetic trunk also refers to thechain of paravertebral ganglia.
COLLATERAL
These are sympathetic ganglia. There arethree of them:
*celiac ganglionsuperior mesenteric ganglion,inferior mesenteric ganglion.
TERMINAL
These are parasympathetic ganglia. They arelocated within the wall of the organ beingsupplied. They are very small and will notbe visible in the laboratory.
PREGANGLIONIC CELL LOCATION
THORACOLUMBAR:
For the sympathetic division the pregan-glionic cell body is located between sectionsT1 -T12 and Ll- 11 of the spinal cord, hencethe synonym thoracolumbar nervous systei-The cell body itself is known as a LateralHorn Cell.
CRANIOSACRAL:
For the parasympathetic division the pregan-glionic cell body is located in either thebrain stem or the sacral region of the cord,hence the synonym craniosacral nervoussystem. The specific nerves involved are:cranial nerves III, VII, IX, at, <, and spinalnerves S2-S5.
NEU ROTRANSMITTERS:The synaptic neurotransmitter used at thepostganglionic synapse differs for the twosystems.
ADRENAUN
The sympathetic system uses adrenalin,epinephrine, or norepinephrine as its neuro-transmitter, hence the synonym adrenergicnervous system.
ACETYLCHOLINE
The parasympathetic nervous system usesacetylcholine as its neurotransmitter, hencethe synonym cholinergic nervous system.
Lecture Notes Part I 48 Nervous System57
HYPOTHALAMIC CONTROL:The sympathetic nervous system is regulatedby the posterior and lateral regions of thehypothalamus, including the area known asthe mammillaty bodies.
The parasympathetic system is regulated bythe anterior and medial regions of the hypo-thalamus.
tve.,e term autonomic imp es regu ton and
adjustment.
The sympathetic system generally mobilizesand expends energy, and preserves theindividual's existence.
The parasympathetic system generallyconserves and stores energy resources andpreserves the species.
EMERGENCY ACTION:In addition to its homeostatic function, thesympathetic system is also capable of a massdischarge, causing large amounts of adrena-lin to be released from the adrenal medulla.This type of mass action causes pronouncedphysiological changes known as the fight orflight syndrome.
HOMEOSTASISThe dramatic effects of a mass discharge ofthe sympathetic nervous system in stressfulsituations (fight or flight syndrome changes )should not obscure the fact that the sympa-thetic nervous system also functions everyday, every hour, every minute to give a tonicbalancing effect.
The end result achieved by the ANS ishomeostatic adjustment and regulation. Bothdivisions are operating constantly to keepthe body in homeostasis
For example, tonic discharges to the arte-rioles maintain arterial blood pressure. Also,stimulation of the sympathetic nerves to the
Lecture Notes Part I
heart causes an increased heart rate withoutnecessarily involving mass discharge to thebody in any generalized way.
SPECIFIC ACTIONS:
SYMPATHETIC:
dilates blood vessels to muscles and skin;constricts blood vessels to viscera;increases the rate & strength of heart
contractions;increases the rate and depth of respiration;dilates the pupil;inhibits saliva flow;inhibits digestive secretions;inhibits peristalsis;constricts the sphincters of bladder and
anus (up to a point);causes ejaculation followed by constriction
of blood vessels to the erectile tissues.
PARASYMPATHETIC:
constricts the blood vessels to muscles andskin ;
dilates the blood vessels to viscera;decreases heart rate;decreases respiration;constricts the pupils;stimulates flow of salivastimulates flow of all digestive secretions;stimulates peristalsis;relaxes sphincters of the bladder and anus;promotes sexual arousal and dilates blood
vessels to the erectile tissues.
'PHYS1Re a ''''
NECTIO
All preganglionic motor nerves exit from theCNS along with the motor root of ordinaryspinal or cranial nerves.
The preganglionic parasympathetic nervessimply stay with the spinal or cranial nerveand travel to their destiAation, but the pre-ganglionic sympathetic nerves must leavethe spinal nerves to get to the ganglion, andthen the nerve exiting from the ganglionmust rejoin the spinal nerve.
49
v8Nervous System
COMMUNICATING RAMThe nerves going to and from the gangliontravel as groups called rami. The pregan-glionic nerves are myelinated so they form awhile ramus communicans. The postgang-lionic nerves are unmyelinated so they forma gray ramus communicans.
lateral horn cell
SPLANCHNIC NERVES;Preganglionic nerves found in the abdomenand pelvis headed for the collateral orterminal ganglia (not the paravertebralganglia. They may be either sympathetic orparasympathetic.
dorsal root clonal root ganglion
1.14\44%..........'1" to effector organ
01
splanchnic new
collatera ganglion
gray rams communicans
white ramus communicans
.....
paravertebral ganglion
sympathetic trunk
to effector organ
Fig 81- Communicating Ram! and Splanchnic Nerves
Lecture Notes Pert I 50 Nervous System
Cranial NervesCranial nerves are typically classified assensory, motor, and mixed. It is not usuallyacknowledged, but any cranial nerve whichcontains a motor component will alsoinclude sensory fibers from the stretchreceptors (proprioceptors) in that muscle.
I. OLFACTORY:Special sensory nerve for the senseof smell. The receptors are actuallybrain cells that begin in the mucousmembrane of the nose and thenpenetrate the cribriform plate ofthe skull to join the olfactory bulbof the brain. This nerve is unique
optic' duasm'because it is the only knowninstance in which brain cellsthemselves interface with theenvironment.
zones, each supplied by one of the threebranches of the nigeminaL The mandibularbranch is the one that is both sensory andmotor, the other branches are just sensory.The sensory supply is for pain, touch, andtemperature.
11. OPTIC:Special sensory nerve forlight. The receptors are therods and cones of the retinaof the eye.
III. OCULOMOTOR:Motor nerve: hypoglossal
oaoa. Motor innervation to fourof the six extrinsic (voluntary)muscles of the eye.
b. Parasympathetic innervation to theciliary muscles of the lens and the cir-cular (constrictor) muscles of the iris(pupil).
A. OPHTHALMIC DIVISION:
Sensory from the upper 113of the face, including thecornea of the eye.
B. MAXILLARY DIVISION:
Sensory from the middlezone of the face, includingthe maxilla and upper teeth,and the nose area.
C. MANDIBULAR DIVISION:
Sensory from the lower 1/3of the face, including thejaw and lower teet, and
trigentinal (V) Motor to the muscles of(12"11 " mastication (mainly).winch)
VI. ABDUCENSfacial (V1:1) Motor supply to theauditory (VM) lateral rectus muscle,
gic"WharYngeal O)) which is one ofthe sixvagus (X) extrinsic (voluntary)
eye muscles.
IV. TROCHLEAR:Motor supply to the superioroblique muscle, one of six extrinsic (volun-tary) eye muscles.
Fig. 82- Cranial NervesHtnnan Brain, Left Side, Inferior View
V. TRIGEMINAL:Mixed nerve: 1 'le face is divided into three
VII. FACIAL:Mixed nerve.a. Sensory for tastefrom the anterior 2/"Z ofthe tongue.
b. Motor to the musclesof facial expression.
c. Parasympathetic tothe submandibular andsublingual salivaryglands, tear glands, andmucous glands of nose.
Lecture Notes Part I SI Nervous System
VIII. AUDITORY(also called Vestibulo-cochlear or Auditory-vestibular, or Stato-acoustic): Sensorynerve: two separate divisions, the cochlearnerve (from receptors in the cochlea of theinner ear), is for hearing, and the vestibularnerve (from receptors in the vestibule andsemicircular canals of the inner ear), is forequilibrium.
IX. GLOSSOPHARYNGEAL:Mixed nervea. Sensory for taste from the posterior 1/3of the tongue. Also sensory from the carotidsinus for blood pressure regulation.
b. Voluntary motor to the muscles of thepharynx, for swallowing.
c. Parasympathetic to the parotid salivarygland.
X. VAGUS:Mixed nerve; chiefly parasympathetic.
a. Parasympathetic to all internal organs inchest and abdomen. Slows the heart, con-stricts the airways. promotes peristalsis andpromotes digestive secretions. Innervationfor coughing, sneezing, and vomiting re-flexes.
b. Voluntary motor to pharyngeal musclesfor swallowing, and to larynx muscles forspeech.
c. Sensory from the:
a. tongue (taste),
b. carotid &aortic bodies (blood press
c. larynx, throat, trachea, esophagus, andinternal viscera of chest and a)domen(temperature and stretch receptors).
XI. SPINAL ACCESSORY:Motor to skeletal muscles in neck area.
a. to muscles of pharynx and larynx forswallowing and speech.
Lecture Notes Part 1 52
b. to sternocleidomastoid and trapeziusmuscles.
XII. HYPOGLOSSAL:Motor to the tongue muscles for speech andswallowing.
Cl Nervous System
Ventricles, Spinal Fluid, Meninges, Blood Supplyitt
Nk,
3.5K:045es,
LATERAL VENTRICLES:Also called ventricle I and II, there is oneinside each cerebral hemisphere.Each is a fairly largecavity with a complexshape, includinganterior horn, poste-rior horn, and lateralhorn.
1IIRD VENTRICLE:
A small slit-like (ex-tremely narrow)cavity in the center ofthe diencephalon.
NTH VENTRICLE:Lies between thecerebellum and ponsin the hind brain. It iscontinuous with thecentral canal of thespinal cord. It is describedas beingthe shape of a threedimensional diamond.
anterior hornof ventricle II
ventricle
body ofventricle
II
VYk.
0609
FORAMENA OF FOURTH VENTRICLE:
There are two lateral foramena (foramena ofLuschka) and one midline foramen (foramenof Magendie). The Pith Ventricle con-
nects with the subarachnoid space s ct.
these openings.root Me p:ze.24.411.
iftlyiv '4
Ittn*-S
t4
ilk`rinferior hornikof ventriclelkt,t
posterior hornof ventricle - 44
FORMATION:The Choroid Plexus con-stantly secretes cerebralspinal fluid into theventricles. The choroidplexus is thought to bea combination of the
"In cerebral specialized capillariesof the ventricles inter-twined with the epen-
dymal cells lining theventricles. The process
of formation is thought tobe one of selective filtra-tion or secretion.
" s
PASSAGE!=.
ventricleIV
Fig. 83- Ventricles, Superior Viewshown superimposed upon the cerebral
hemispheres
anterior horn
body ofventricle II
FUNCTIONCerebral spinal fluid
serves as a shock ab-sorber (water cush-ion or water jacket),protecting the brainand spinal cord.There is some evi-dence that it mayprovide a circulationpathway for certainnatural chemicals orhormones.
INTERVENTRICULAR FORAMENA
Also called Foramen ofMonro: connects each ofthe lateral ventricles to th.,IlIrd ventricle.
CEREBRAL AQUEDUCT :
Also called Aqueductof Sylvius: connectsventricle III with ven-tricle IV; a long canalwhich passes length-wise through themidbrain.
ventricle IVinferior horn
cerebral aqueduct
Fig. 84- Ventricles, Lateral Viewshown superimposed upon the cerebral
hemispheres
Lecture Notes Part 1 53
6 2Nervous System
CHARACTERISTICS OF CSF:Cerebral spinal fluid is a clear, watery, strawcolored filtrate of blood plasma. It is sterile,and normally it should be free from red andwhite blood cells. It contains small amountsof protein, glucose, and chloride. The vol-ume ranges from 80-200 ml, the average foradults is 100-140 ml, with 15 ml beingfound in the ventricles, the rest in the subar-achnoid space. Samples of the fluid areusually obtained for analysis by lumbarpuncture.
CIRCULATION OF CSF:Cerebral spinal fluid leaves each lateralventricle by way of the Foramen ofMonro; it leaves the IIIrd ventricle by wayof the Aqueduct of Sylvius; it leaves theIVth ventricle by way of the foramens ofLuschka and Magendie, and enters thesubarachnoid spaces. From there it entersthe superior sagittal sinus (vein) by way ofthe arachnoid villi.
REABSORPTION OF CSF:Since the CSF is being formed constantly, itmust be reabsorbed constantly, otherwise theintracranial pressure would rise, with seriousconsequences. Reabsorption is by way of thearachnid villi into the venous superiorsagittal sinus.
MAN,WeW
DURA MATER:The outermost sheath of tough, dense,elastic connective tissue surrounding thebrain and spinal cord.
The spinal dura extends all the way down toS2. It ensheathes the whole cord and thecauda equina, and extends out around thedorsal and ventral roots of the spinal nerves.There it feathers out to become the thinnerepineurium covering the nerve
The dura surrounding the brain has threeextensions. Each of these is a double fold ofJura that projects inward into the fissures,
effectively partitioning the cranial space intosmaller compartments.
FALX CEREBRI
FALX CEREBELU
TENTOFNUM CEREBELL1
falx catabri inferior sagittal sinussuperior sapid'sinus frontal airs'
mai&sinus
7141plimpir
sisinus
transversesinus
externaljugular Vein
Fig. 85- Faix Cerebri and Venous
Drainage of the Brain
ARACHNOID MATER:Delicate, serous, connective tissue beneaththe dura; it does not dip down into the sulci,but lies close to the dura all the way. Thename implies it's spider web like appear-ance. The following are noteworthy featuresof the arachnoid:
Cavernoussinus
sphenoidair sinus
opthahnic
V I
facial
jugular vein
ARACHNOID TRABEr t1LAE
ARACHNOID V1LU (ARACHNOID GRANULATIONS)
SUBARACHNOID SPACES:
Lumbar CisternGreat Cistern(Cisterna Magna)Superior CisternInterpeduncular CisternPontine Cistern
PIA MATER:Thin, delicate, highly vascular, connective
Lecture Notes Part I 54 Nervous System63
tissue that adheres to the surface of the brainand cord and dips down into all sulci. Thefilum terminals at the inferior end of thespinal cord is made of pia mater.
)
The blood (containing absorbed CSF) drains°tit of the skull by passing sequentially intothe transverse sinus, sigmoid sinus andinternal jugular vein.
If at any time this circulation pathway isblocked pressure will start building up insidethe cranium. If blockage occurs in child-hood, before the sutures of the skull havefused, the head will enlarge. This pathologyis called hydrocephalus.
kkatsisgs. ,
The arteries which supply blood to the brainare the paired vertebral arteries and thepaired internal carotid arteries. Once insidethe skull these four arteries join the Circle of
anteriorpuntinicatinganterior
cerebral
Fig. 86- Blcod Supply to the Brain:The Circle of Willis
Lecture Notes Part I 55
Willis.
The vertebrals enter the skull via the fora-men magnum. They unite on the ventralsurface of the brain stem to form the singlebasilar artery, which then splits to form thetwo posterior cerebral arteries.
The internal carotid arteries enter the skullvia the carotid foramen and carotid canals.Each internal carotid splits into a middlecerebral artery and an anterior cerebralartery.
The two anterior cere'lrals join via theanterior communicating artery. Each middlecerebral artery joins with the posteriorcerebral artery via the posterior communi-cating artery.
Common nutritive substances like glucoseand oxygen pass freely into the brain tissue,as well as into the CSF, but if chemicalspotentially capable of disrupting brainfunction are introduced into the bloodstreamthey will be screened out (except Na+, K+,and certain drugs). The only area of thebrain excepted is the posterior inferiorregion of the brain stem (part of the medullaoblongata), which is the location of thecenter that controls the vomiting reflex.
Mechanisms: The present theory is that thecapillaries of the brain create the barrier,there are no pores in the capillary walls inthe central nervous system, therefore sub-stances must penetrate the capillary wallsdirectly. Another theory is that astrocytes actas middlemen, carrying substances from thecapillaries to the nerve cells. Not all sub-stances passing through the capillaries areable to enter the astrocytes.
64 Nervous System
Fig. 87- Human Brain, Left HemisphereInferior View
Lecture Notes Part I 56C5
Nervous Syswm
1 I 55 II
I 'I
0 I 0 0
t 1 i'\sk
-$-\1 V} dt
1 I I I I I 1
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The more "cerebral" (advanced or corn- The cerebral cortex of humans is moreplex) a behavior is, the more likely it is to dense with cells than that of any otherbe controlled by the forebrain. animal.
Fig. 90- Sagittal Section of Adult Human Brainshowing further subdivision of the three primary regions.
Fig. 91- Human Brain, inferior Viewshowing subdivisions of the telencephalon
ki
}
telencephalon
diencephalon
mesencephalon
metencephalon
[0] mylencephalon
RETICULAR FORMATION:In the core of the midbrainand hindbrain (running thruthe white matter of the me-dulla, pons and cerebralpeduncles) is the so calledreticular formation, a networkof neurons through whichsensory pathways on the wayto the cortex must pass.
The reticular formation appar-ently screens information,blocking irrelevant materialand passing through that
which is relevant,thus helping to pre-
rhinencephalon vent information(limbic system) overload.
neopalliumAnother function ofthe reticular forma-tion is to alert higher:enters that a bar-rage of sensory in-formation is soon toarrive.
Lecture Notes Part I ss 67 Nervous System
Adult Anatomy of the Brain
MYELENCEPHALON
MEDULLA OBLONGATAThe medulla oblongata is the lowest andoldest part of the brain. It is directly con-tinuous with the spinal cord below and thepons above. The pyramids of medulla aretwo swellings on the anterior surface of the
medulla; they contain the corticospinaltracts. The corticospinal tracts physicallycross from left to right and vice versa at thelevel of the medulla. This cross over isknown as the decussation of the pyramids.
CRANIAL NERVE NUCLEI
Cranial nerves IX, X, XI, XII are attachedto the medulla, therefore we can say that themedulla regulates: respiration, heart beat,blood pressure (vasoconstriction), sleep,consciousness, and reflex functions such asswallowing, vomiting, sweating, and gastricsecretion.
filETENcEPHALON
CEREBELLUMCEREBELLAINORTEX;
The cerebellar cortex is the gray matter onthe surface of the cerebellum. It containsthe cell bodies of nerves that control musclecoordination, muscle tone, posture, equilib-rium, and muscle memory (habit formation).
The cerebellum receives sensory input(cues) related to the above: i.e. proprio-ception from muscles, tendons, and joints;visual cues, auditory cues, vestibular organcues, and touch cues.
CEREBELLAR PEDUNCLEt
The cerebellar peduncles are white mattertracts that connect the cerebellar cortex withother parts of the brain which are abovebelow and across the street from the cereJel-lum.
superiorpedundesConnects cerebellum to midbrain.middle peduncles:Connects cerebellum to pons.inferior pedunclesConnects cerebellum to medulla.
ARBOILVITAQ
The arbor vitae is a branching pattern oftracts with a fanciful resemblence a tree.These tracts are simply the continuation ofthe cerebellar peduncles.
PONSThe pons is mostly white matter because allascending P.nd descending neurons mustpass through it, there is no other way foraxons to travel up to higher centers or downto lower centers.
CRAWL NERD NIICLE;
Cranial nerves V, VI, VII, VIII areattachedto the pons in an area called the olive.
CEREBRAL PEDUNCLESAll ascending and descending neurons mustpass through the white matter of the cerebralpeduncles of the midbrain, there is no otherway to go up to higher centers or down tolower centers. Two examples of such path-ways are the corticospinal (voluntary motor)and spinothalamic (sensory) tracts.
PEP NUCLEUS;
The red nucleus is a mass of gray matterwhere axons from the cerebral cortex syn-apse with axons going to the cerebellum viathe superior cerebellar peduncles.
CRANIAL, NUCLEIC
Cranial nerves III, IV, and l st division ofVth are attached to the cerebral peduncles.
CORPORA QUADRIGEMINAThe corpora quadrigemina are four bodies
Lecture Notes Part I59 68 Nervous System
(two pairs) of gray matter in the midhrain.There is a pair of superior colliculi and apair of inferior colliculi.
UPERIOR COLLICULI;
These nuclei control visual reflexes such as:blinking, accommodation, pupillary con-striction and dilation. They also controlbalance reflexes related to visual cues. Theoptic nerves go first to the lateral geniculatebodies of the thalamus, and then some of theaxons continue on to the superior colliculi.The two superior colliculi are connectedwith one another via a band of axons calledthe posterior commissure.
INFERIOR COLUCUU;
These paired nuclei control auditory reflexessuch as the tensor tympani and stapediusreflexes. They also control balance reflexesrelated to vestibular cues. The vestibularnerves go first to the medial geniculatebodies of the 0- **Ins, and then some of theaxons contito t the inferior colliculi.
3.
plENCEPHALAN
THALAMUS:All afferent (sensory) fibers (except olfac-tion) synapse in the thalamus before beingrelayed to the cortex. The thalamus providesthe lowest level of sensory discrimination(pleasant vs unpleasant, touch vs pain,temperature vs pain), but the sensation isunlocalizedunless the relay continues to thecerebral cortex.
1,ATE6AL GENICULATE BODIES;
These nuclei are the relay stations for theoptic nerve axons. From here messages arerelayed to the occipital lobe of the cortex forimage formation or to the superior colliculusfor visual reflexes, or to the pineal gland forbiological clock functions. This latter con-necti,A is still considered speculative.
MEDIAL GENCULATE BODIES;
Connections for cranial nerve VIII. Fibersarrive here from the Vestibular and Cochlearnuclei of the brain stem (pons). From herefibers are sent to the auditory cortex forhearing, or to the inferior colliculus forauditory reflexes.
EPITHALAMUS (PINEAL BODY):The pineal body is tentatively implicated asa biological clock mechanism, especially asconcerns the onset of puberty, perhapsconverting circadian dark/light cycles intoendocrine cycles.
HYPOTHALAMUS:Control centers (nuclei) for:
body temperaturecontrol of anterior pituitary gla.'d via
production of releasing factorsproduction of posterior pituitary
hormones (ADH and Oxytocin)sleep/wake cycleslibido (sex drive)hungerthirstregulation of autonomic nervous systemregulation of emotional behavior via
limbic system connections to mammillarybody nuclei).
TELEN_CcPHALON
RHINENCEPHALON (LIMBIC SYSTEM)The rhinencephalon or "nose brain" is some-times called the archipallium, indicating thefact that it is the oldest part of the telenceph-alon.
WHITE MATTER;
olfactory nerves, tracts &striaeThese extend from the olfactory bulbsleading to the uncus, anterior perforatesubstance,amygdala, hippocampus andcingulate gyrus.
fornixConnects amygdala and hippocampus of thelimbic system to the mammillary bodies of
Lecture Notes Part I 609
Nervous SystemC
hypothalamus and to the brain stem, allow-ing the limbic system to influence theautonomic nervous system and emotionalbehavior.
anterior commissureFound at the proximal end of the olfactorynerves. Connects the olfactory tracts to eachother.
COLIEWLEACEEXASSMAIMEAS451olfactory bulbs
anterior perforate substanceAlso called the olfactory trigone since it isa triangular area between the olfactory tractsand olfactory striae.
uncusThe uncus is the smooth anterior end of thecollateral gyms.
hippocampusThe hippocampus is a part of the collateralgyrus which is coiled like the tail of aseahorse.
cingulate gyrusThis gyrus is above the corpus callosum andparallel to it.
XLCLE1;
amygdalaThe amygdala is an almond shaped nucleusdeep in the center of each temporal lobe.
NEOPALLIUM:The neopallium is approximately 7/8 byweight of the human brain.
=ELsulci and fissures:midsagittal fissureThis fissure is also known as the medianlongitudinal fissure. It divides the cerebralcortex into two hemispheres.
central fissureThis fi ;sure is also known as the fissure orRolando. It marks the boundary between thefrontal lobe and the parietal lobe.
lateral fissurrThis fissure is also known as the Sylvianfissure. It separates the temporal lobe fromthe frontal lobe.
parieto-occipltal AssureThis fissure can be seen from the midsagittalview only. It marks the boundary betweenthe parietal lobe and the occipital lobe.
calcarine fissureThis fissure can also be seen only from themidsagittal It starts at the occipital pole andruns forward at right angles to the parit...)-occipital fissure.
collateral fissureThe collateral fissure runs lengthwise on theinferior surface of temporal lobe.
cingulate sukusThe cingulate sulcus is above the cingulategyrus, which is above the corpus callosum.
transverse fissureThe transverse fissure separates the cerebel-lum from the occipital pole.
lobes:frontalparietaloccipitaltemporalinsula
CORTICAL PROJECTION AREAS:
These are the t. learly localized sensory andmotor areas also known as primary cork
precentral gyrus:ThiF gyrus of the frontal lobe is the primarymotor cortex
postcentral gyrus:This parietal lobe gyrus is the primarysensory cortex
walls of calcarine fissure :This cortex of the occipital lobe is theprimary visual cortex.
motor speech area:The motor speech area is in the dominanthemisphere; it is the part of the frontal lobewhich is just above Sylvian fissure and just
Lecture Notes Part I17 o
Nervous System
anterior to the precentral gyrus. This area isalso known as Brocca's area
hearing projection area:The primary hearing cortex is located on thesuperior gyrus of the temporal lobe.
COFJTJCAL ASSOCIATION AREAS;
The association areas are the areas of cortexare also known as secondary cortex. Theyimmediately surrounding the primary pro-jection area. These are the areas wherememories and thoughts associated withprimary events are stored.
visual association areaThis is the area of the occipital lobe sur-rounding the calcarine fissure.
hearing association areaThis is most of the temporal lobe immedi-ately surrounding the primary hearing cortex
sensory association areaThis is the part of the parietal lobe immedi-ately posterior to the primary general sen-sory cortex.
language association areaThis is the area of the dominant hemispherewhere the temporal, occipital and parietallobes meet. Also known as Wernicke's area.
insula:The insula is a hidden island of cortex in thewalls of the Sylvian fissure of the temporallobe. This is the speech association area.
prefrontal cortex:The prefrontal cortex is all of the frontallobe anterior to the motor cortex. Theprefrontal lobe is poorly understood, but isassociated with such things as "intelli-gence", reasoning ability, emotional control,long range planning, personality, and moti-vation.
THE BASAL "GANOLIA"
The basal ganglia, or basal nuclei areimportant for the dampening and inhibitingof voluntary motor impulses so that musclesare not overactive, and movements do not
overshoot their target. Rigidity and tremorare characteristic of malfunction of the basalganglia. A band of white matter (the inter-nal capsule) runs between the caudatenucleus and the lentiform nucleus givingthem a characteristic stripped appearance,giving rise to the term corpora striata (basalganglia + the internal capsule).
caudate nucleus
lentiform nucleusglobus pallidusputamensubstantia nigra
NtifELMAZEILinternal capsuleThe internal capsule is a tightly bundledgroup of axons traveling vertically betweenbrain stem and cortex. The bundle passesthrough the middle of the basal ganglia andcontinues upwards as the corona radiata. Seenext listing.
corona radiataMuch of the white matter beneath the cere-bral cortex is the corona radiata. When theascending axons in the internal capsuleescape the confines of the basal ganglia theaxons spread (radiate) out to reach theirdesignated area of the cortex. The sameconcept in reverse applies to the descendingaxons which after leaving the cortex mustfunnel into the brain stem.
corpus callosumThis very large band of axons is the brain'slargest commissure; it allows the hemi-spheres to share information. Without thiscommissure therewould be essentially twobrains rather than one, and each brain wouldbe in control of the opposite side of thebody. Only the dominant side (left side formost people) would have access to lan-guage.
Lecture Notes Part I 62 Nervous System
71
Major Pathways of the Brain
This is the pathway for pain and tempera-ture sensations traveling from skin tothalamus to sensory cortex. The decussation(cross over) is at the spinal cord level sothat sensations coming from one side of thebody immediately cross to the other side ofthe cord and then travel upward towards thebrain. See Fig. 92.
This is the pathway for light touch andpressure sensations traveling from skin tothalamus to sensory cortex. Again, thedecussation is at the spinal cord level so thatsensations coming from one side of thebody immediately cross to the other side ofthe cord and then travel upward towardsbrain. See Fig. 92.
This is the pathway for proprioception,stereognosis, tactile discrimination andsome pressure sensations raveling fromskin to thalamus to sensory cortex. The de-cussation is at the level of the medulla,which means that sensations coming fromone side of the body travel upward on thatsame side of the cord until they reach themedulla, at which point they cross over andtravel upward on the opposite side of thebrain stem (medulla, pons, cerebralpeduncles) towards the thalamus and cortex.
This is the pathway for voluntary motorimpulses traveling from the motor cortex ofthe brain down through the brain stem andinto the spinal cord, where they synapse onthe anterior horn cells of the spinal cord.The decussation is at the level of the me-dulla (decussation of the pyramids), and infact the swellings known as the pyramids ofthe medulla are in reality these corticospinaltracts.
Lecture Notes Part I 63 Nervous System
insula
corpus
callostun
lateral
ventricle
caudate
nucleus
third
ventricle
Coronal
Section
Hum
an
Brain
Cross
Section
Spinal
Cord
cerebral
peduncles
thalamus
lentiform
nucleus
internal
capsule
pain
and
temperature
touch
lateral
funiculus
ventral
funiculus
Fig.
92-
Lateral
and
Ventral
Spinothalam
ic
Tracts
The
lateral
sp'iothalamic
tract
is the
pathway
for
pain
and
temperature.
The
ventral
spino-
thalamic
tract
is the
pathway
for
light
touch.
Notice
that
each
pathway
requires
three
neurons,and
that
each
pathway
crosses
to the
opposite
side
at the
level
of the
spinal
cord.
Lecture
Notes
Part
I 64 73
Nervous
System
General Sensory Receptors
TRANSDUCERS:
Sense receptors are transducers; they changeone form of energy (e.g. heat, sound waves,pressure) into another form of energy (intoelectrical signals for example). Biologicaltransducers change one form of energy (e.g.light, heat, sound waves, pressure) intonerve impulses, which are actually electro-chemical signals acting on cell membranes.
ADEQUATE STIMULUS:
Each receptor has it's specific "adequatestimulus", i.e. the energy form which nor-mally excites it. Usually there is no crossover stimulation unless the stimulus is veryintense (e.g. very intense sound is painful).
ADAPTATION:
Most receptors adapt in the presence of aconstant level of stimulus. What actuallyhappens is that they send fewer nerve im-pulses, (i.e. they "fire" at a slower rate)
'CATALOG..OFSENS..
TOUCH:
PRESSURE:
PAIN:
COLD:
HEAT:
PROPRIOCEPTION:
Lecture Notes Part I
when the level of stimulus is unchanging.Mostly we respond to change and tend todisregard a steady state. The exception tothis is that pain and tendon stretch receptorsdo not adapt.
REFERRED PAIN:
Pain that actually originates in a visceralorigin may feel as though it is coming fromsomewhere else. The explanation for this isprobably as follows: the visceroceptorneuron is traveling in a mixed spinal nervealong with a peripheral sensory neuron.Both neurons probably activate the sameinternuncial neuron in the central nervoussystem. Since stimulation of sensory re..zp-tors in the viscera is relatively uncommonthe brain assumes that the signal is comingfrom the peripheral sensory neuron, and thusmisinterprets the source or origin of thesensation. For example: in angina pectoris,the source of the pain is in the heart muscle,but tilt, pain is commonly experienced to bein the left chest, shoulder, and arm area.
Meissner's corpuscles in hairless skinTactile discs (Merkel's discs)Hair root plexuses
Pacinian corpuscles
Free nerve endings in skin, connective tissue, andcornea.
Krause's end bulbs (corpuscles)
Ruffini's brushes (corpuscles)
Neuromuscular spindles (stretch receptors), arefound in all muscles and joints. They give constantinformation to the brain regarding muscle and jointpositi'n and movement.
65 74Nervous System
TENDON LOAD:
EXTENSOR STRETCH REFLEX:
GRAVITY:
Golgi tendon organs (stretch receptors in thetendons). If a tendon is stretched to the breakingpoint the muscle will suddenly relax and the jointwill col-lapse, preventing injury to the tendon andmuscle. (clasp knife reflex)
Neuromuscular spindles (stretch receptors) found inthe muscles of the feet will , when stretched, causeincreased contraction of the extensor muscles in thelegs. This reflex is activated when the soles of thefeet are pressed against the floor, causing the legextensors to hold the individual upright,
Utricle and Saccule of the inner ear give in-formation to the brain that allows the body to orientto gravity (ability to know up from down); recogni-tion of head position.
ACCELERATION/ DECELERATION: Semicircular canals of the inner ear.
SOUND: Cochlea &organ of Cord of the inner ear.
SIGHT: Retina, rods and cones
TASTE: Taste buds in papillae of the tongue for sweet, sour,salty and bitter, Other flavors are a combination oftaste and olfaction
SMELL: Chemoreceptors in mucosa of upper nasal cavity
BLOOD PRESSURE: Stretch receptors in aortic arch, carotid sinuses, andin superior and inferior venae cavae. Impulses fromthese receptors are carried by the glossopharyngealnerves.
BLOOD CO7 :
BLOOD SALINITY:
BLOOD GLUCOSE:
VISCERAL SENSATIONS:
Chemoreceptors found in the aortic body andcarotid bodies are sensitive to acid levels (CO2dissolved in water creates carbonic acid); increasedCO2 levels causes faster breathing.
Osmotic receptors in hypothalamus
Glucostat receptors in hypothalamus (?)
Very few sense receptors exist in the viscera, touchsensibility is virtually nonexistent , warmth and coldsensibility is almost nonexistent . The few receptorsthat exist an called interoceptors or visceroceptors.They respond to pain and distension (internalstretch) of the vis,..era.
Lecture Notes Part 1 66 5 Nervous System
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THE EYE
The eye has three basic layers and four basicfunctions.
THREE BASIC LAYERS:
OUTER LAYER
The outer layer of the eye includes the scleraand the cornea.
MIDDLE LAYER:
The middle layer of the eye includes thechoroid layer, the iris, and the ciliary body.
INNER LAYER:
The inner layer of the eye consists of theretina.
FOUR BASIC FUNCTIONS:The sclera and cornea protect the retina.
The iris and choroid layer regulate theamount of light that hits the retina.
The cornea, lens, and ciliary body focusthe light on the retina.
The retina transduces the light stimulusby changing it into nerve impulses.
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SCLERAThe sclera is very tough thick white connec-tive tissue; its function is to protect theretina.
CORNEA:The cornea is the transparent front portion ofthe sclera. In addition to protecting the retinait is also does most of the focusing.
CHOROIDThe choroid layer of the eye is black due toits massive amounts of melanin pigment.
ac pigment protects e retinatina byabsorbing excess light.
IRIS:The iris is the forward extension of choroidlayer. It contains less pigment than thechoroid. Different eye colors in differentpeople are the result of varying amounts ofthe pigment melanin in the iris.
PUPIL:
The pupil is a hole in the center of the Iris.The size of the hole will change dependingon the brightness of the ambient light.
MUSCLES OF THE IRIS
(pupil size regulation)
Circular LayerContraction of the circular muscles of theiris will dilate the pupil.
Radial LayerContraction of the radial muscles of theiris will constrict the pupil.
CILIARY BODY AND LENSAdjustment of the ciliary body will changethe shape of the lens which in turn willchange the focal length of the lens. Thisprocess is called the "accommodationreflex".
ELASTIC LENS
In order to be transparent the lens has noblood vessels and no nerves, and its cellshave lost all their internal structures (duringembryological development), leaving themunable to replicate or to produce their ownenergy, and yet the lens continues to grow asthe body grows.
The lens has the most concentrated proteincontent of any tissue in the body. As muchas 60% of the lens is made of a special classof proteins called crystallins. These specialproteins perform a dual function:
a. they act as structural proteins dense
Lecture Notes Part I 6' Nervous System
enough to bend light efficiently
b. they act as enzymes capable of con-verting sugars into energy to keep thecells of the lens alive.wistow & Piatigorsky, Science, June 19, 1987
SUSPENSORY LIGAMENTS
These are very delicate crystal clear strands.One end attaches to the circumference of thelens, the other end of each ligament isattaches to a ciliary muscle.
CILIARY MUSCLES
The ciliary muscles are used in the visualreflex known as accommodation, as in thephrase accommodation for near vision. Theyare smooth muscle, and they work by adjustthe shape of the elastic lens from the restingflattened position needed for distance vision,to a rounder shape which is needed for nearvision.
Contraction of the ciliary muscles willreduce tension on the suspensory ligamentsthus allowing the elastic lens to fatten Thisis the shape needed for focusing on closeobjects.
Relaxation of the ciliary muscles willir -Tease tension on the suspensory liga-ments, stretching the elastic lens into aflatter shape. This is the shape needed forfocusing on distant objects.
RETINA
RODS
The rods are receptors for night vision, theycontain the visual pigment rhodopsin.Rhodopsin is purple in the dark (visualpurple); low intensity light causes a chemi-cal reaction in the rhodopsin which in turninitiates a nerve impulse. The color red isnot visible at night because rhodopsin is notsensitive to light waves in the red range.When exposed to bright light, rhodopsinbleaches to white and nerve impulse cease.The bleaching reaction is reversible; the
bleached pigment will become purple againwhen protected from the light.
CONES
The cones are for color vision and acutevision. They contain a variety of visualpigments that are sensitive to all the differ-ent lengths of light waves in the visualspectrum.
MACULA LUTEA
White spot at rear of the eyeball where theretina is thicker.
FOVEA CENTRALS
A pit in the center of the macula lutea. Thisis the area of most acute vision the to a highconcentration of cones and the absence ofrods in this area.
BIPOLAR CELL LAYER
Very short neurons. Anterior to the rods andcones. These neurons are stimulated by thechemical changes in the rods and cones.They in turn synapse with the optic nervecells.
OPTIC NERVE FIBERS
These cells synapse with, and lie anterior to,the bipolar neurons. Light must pass througha tangle of optic nerve fibers and the bipolarlayer of cells before it can strike the rodsand cones of the retina. The optic nerveaxons converge on the optic disk at the backof the eye.
OPTIC DISK
The optic disk is the area at the posteriorpole of the eyeball where the optic nervesexit the eyeball to continue their journey tothe brain. Since there is no retina at thislocation, the optic disk causes a " blindspot" in each eye. As long as a person hastwo eyes no dysfunction is caused becausewhen light is striking the blind spot in oneeye it simultaneously falls on active retina inthe other eye.
EXTRINSIC EYE MUSCLES :These are the muscles attached to the out-side surface of the eyeball and used formoving the eye in the direction of sight.
Lecture Notes Part I 68 77 Nervous System
They are all voluntary (skeletal) muscle asopposed to the intrinsic muscles of the eye(ciliary muscles and two iris muscles) whichare all smooth muscle.
SUPERIOR RECTUS
LATERAL RECTUS
for abduction of the eye
MEDIAL RECTUS
INFERIOR RECTUS
SUPERVI OBLIQUE
it runs through the trochlea
INFERIOR OBLIQUE
LACRIMAL GLAND
VITREOUS HUMOR
IVIENT
VITREOUS CHAMBER
AQUEOUS HUMOR
This fluid is constantly secreted by theepithelium of the ciliary body.
ANTERIOR CHAMBER
POSTERIOR CHAMBER
CANAL OF SCHLEMM
CONJUNCTIVA
FAT PAD
VISUAL DEFECTS:PRESBYOPIA
The farsightedness of aging; caused by lossof elasticity in the lens.MYOPIA
Congenital nearsightedness; caused by aneyeball which is too long from front to back,resulting in a focal point which falls short of(in front of) the retina. The image is thus outof focus again when the light waves reachthe retina.
HYPEROPIA (HYPERMETROPIA)
Congenital farsightedness; caused by aneyeball which is too short from front toback, resulting in a foca point which fallsbehind the retina. The image is thus not yet
in focus when the light waves hit the retina.
ASTIGMATISM
Congenital difficulty in focusing due tovariable thicknesses (waviness) of thecornea and/or lens.
CATARACTS
Opacity of the cornea or lens. Numerouscauses. Frequently associated with the agingprocess.
DETACHED RETINA
The retina is held smoothly in place againstthe sclera by the vitreous humor. If theretina falls away from the sclera light willnot focus on it and sight is lost in that area.
GLAUCOMA
Aqueous 'humor must drain out of the eye atthe same rate at which it is produced, other-wise pressure will build up
CONJUNCTIVMS
EXOPHTHALMIA
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8Nervous System
THE EAR
The features of the external ear that are ofinterest include the pins, the helix, thelobule, the external auditory canal, and theceruminous glands.
TYMPANIC MEMBRANE
EAR OSSICLES:MalleusIncusStapes
WINDOWS:RoundOval
MUSCLES:Tensor TympaniStapedius
EUSTACHIAN TUBEAlso known as the pharyngotympanic canal.
BASIC CONSTRUCTIONBony LabyrinthMembranous LabyrinthEndo lymphPeri lymphHair Cells
ORGANS OF EQUILIBRIUM
VESTIBULE
The vestibule functions for stationary equi-librium, i.e.the sense of gravity and headposition.
Bony VestibuleUtricleSaccule
Lecture Notes Part I
SEMICIRCULAR CANALS
The semicircular canals function for "dy-namic" equilibrium, i.e. acceleration- decel-eration.
Bony semicircular canalsSemicircular ducts
AmpullaeEndolymph
ORGAN OF HEARING (COCHLEA)
MODIOLUS
COCHLEAR DUCT
SCALA VESTIBUU
Vestibular Membrane
SCALA TYMPANI
Basilar Membrane
ORGAN OF CORTI:
Tectorial Membrane
COCHLEAR FUNCTIONS
LOUDNESS RESPONSE
Modifications of amplitude.
PITCH RESPONSE
Modifications of frequency.
Nervous System
