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Anatomy and Physiology
Mark Neil V. Dancel, RN
THE SKELETAL SYSTEM
Skeleton comes from the Greek word meaning
“dried up body” Contains a total of 206 bones Subdivided into 2:
Axial Skeleton Appendicular Skeleton
BONES: AN OVERVIEW
FUNCTIONS OF THE BONES Support
Forms the internal framework of the body and anchors all soft organs (internal organs)
BONES: AN OVERVIEW
FUNCTIONS OF THE BONES Protection
Protect soft body organs
BONES: AN OVERVIEW
FUNCTIONS OF THE BONES Movement
Acts like levers to move the body and its parts
BONES: AN OVERVIEW
FUNCTIONS OF THE BONES Storage
Fats is stored in the internal cavities of bones
A storehouse for minerals (calcium)
BONES: AN OVERVIEW
FUNCTIONS OF THE BONES Blood Cell
Formation Hematopoiesis
occurs within the marrow cavities of certain bones
CLASSIFICATION OF BONES
Two Basic Types of Bone Tissue: Compact Bone
Dense, smooth and homogenous
Spongy Bone (Cancellous) Small needlelike
pieces of bone (trabeculae) and open spaces
CLASSIFICATION OF BONES
ACCORDING TO SHAPE Long Bones
typically longer than they are wide They have shafts and heads at both ends
Short Bones Generally cube-shaped Contain mostly spongy bone
Flat Bones Thin, flattened, and usually curved Have 2 thin layers of compact bones and a
layer of spongy bone in between Irregular Bones
Bones that do not fit the preceding categories
CLASSIFICATION OF
BONES
A
CC
OR
DIN
G
TO
S
HA
PE
STRUCTURE OF A LONG BONE Gross Anatomy
Diaphysis or shaft Makes up most of the bone’s length Composed of compact bone Storage area (Medullary cavity) for fats (in
adults) or blood cells (in infants) METAPHYSIS
The site of ossification, between the diaphysis and epiphysis
Periosteum A fibrous tissue membrane covering and
protecting the diaphysis Sharpey’s Fibers
Secure the periosteum to the underlying bone
Epiphyses Ends of a long bone
Articular Cartilage Covers the external surface of the
epiphysis
STRUCTURE OF A LONG BONE Microscopic Anatomy
Osteocytes Mature bone cells
found in tiny cavities within a matrix called LACUNAE
Lacunae are arranged in concentric circles called LAMELLAE around central (Haversian) canals
Haversian System or Osteon A complex consisting of
central canal and matrix rings
BONE CELL TYPES A) OSTEOPROGENITOR CELLS: The Stem-Cells of bone.
DISTRIBUTION: Found on the inner lining of the periosteum and endosteum. Found lining vascular canals.
B) OSTEOBLASTS: They are secretory cells. SECRETE:
They secrete the bone matrix. ALKALINE PHOSPHATASE which calcifies the matrix.
They have polarity and resemble other secretory cells. C) OSTEOCYTES: They are osteoblasts that have become
trapped in their own matrix. They are found in lacunae, between layers of lamellae, in the matrix
of cortical bone. The lacunae are potential spaces, filled with extracellular fluid in real life.
CANALICULI: Fine cytoplasmic extensions of the osteocytes running perpendicular to the haversian canals.
D) OSTEOCLASTS: Large, multinucleate cells derived from monocytes. They have acid hydrolases which have a Mannose-6-Phosphate
Receptor that targets them to lysosomes within the osteoclasts. Osteoclasts have many lysosomes and are eosinophilic.
BONE FORMATION, GROWTH, AND REMODELLING
OSSIFICATION Two Major Types:
Intramembranous Ossification
Involving direct mineralization of richly vascular dense connective tissue membrane
The membrane itself becomes the periosteum
Immediately within are the compact bones with an inner core of cancellous bone
BONE FORMATION, GROWTH, AND REMODELLING
Endochondral Ossification Replacement of a “scale model” of
hyaline cartilage by bone. Bone is formed on a cartilage model. The formation of the bone itself is
identical to intramembranous type.
ENDOCHONDRAL OSSIFICATION
ENDOCHONDRAL OSSIFICATION
GENERAL PROCESS Cartilage matrix is laid down. Perichondrium then becomes periosteum, when
a vascular bud invades the perichondrial space. The Vascular Bud contains blood cells, bone marrow
cells, macrophages, endothelial cells. GROWTH IN LENGTH:
Occurs by proliferation of chondrocytes at the epiphyseal plates and at the primary ossification front.
GROWTH IN DIAMETER: Occurs by deposition of new bone under the
periosteal collar along with simultaneous osteoclastic resorption, in order to maintain bone shape.
The osteoclastic resorption is necessary to enlarge the medullary cavity.
ENDOCHONDRAL OSSIFICATION
PRIMARY OSSIFICATION CENTER Occurs in the center of the diaphysis, and extends
toward both epiphyses. Thus there are two fronts of primary ossification. Primary Ossification Centers close around the time of
birth. Thereafter, long-bone growth occurs from the secondary ossification centers.
SECONDARY OSSIFICATION CENTER Forms at the epiphyseal plate.
The orderly columns of chondrocytes are not seen here. Growth occurs from the epiphysis downward, toward
the epiphyseal plate. EPIPHYSEAL CLOSURE
The end of longitudinal growth in long bone, when the primary ossification center overtakes (i.e. calcifies) the secondary ossification center, and hence long-bone growth ceases.
BONE MARKINGSNAME OF BONE MARKING
DESCRIPTION
Projections (Muscle and Ligament Attachment)
Tuberosity
Crest
Trochanter
Line
Tubercle
Large, rounded projection;May be roughened
Narrow ridge of boneUsually prominent
Very large, blunt, irregularly shaped process
Narrow ridge of bone, less prominent than a crest
Small, rounded projection or process
BONE MARKINGSNAME OF BONE MARKING
DESCRIPTION
Epicondyle
Spine
Process
Projection (form joints)
Head
Facet
Condyle
Ramus
Raised Area on or above a condyle
Sharp, slender, often pointed projection
A bony prominence
Bony expansion carried on a narrow neck
Smooth, nearly flat articular surface
Rounded articular projection
Armlike bar of bone
BONE MARKINGSNAKE OF BONE MARKING
DESCRIPTION
Depression and Openings
Meatus
Sinus
Fossa
Groove
Fissure
Foramen
Canal-like passageway
Cavity within a bone, filled with air and lined with mucus membrane
Shallow, basin-like depression in a bone, often serving as an articular surface
Furrow
Narrow, slit-like opening
Round or oval opening through a bone
LIST OF BONES
Axial Skeleton Skull
22 bones Throat
1 bone Middle Ears
6 bones Thorax
25 Bones Vertebral Column
26 bones Sub-total : 80
bones
LIST OF BONES
Appendicular Skeleton Upper Extremities
60 bones Shoulder Girdle
4 bones Pelvis
2 bones Lower Extremities
60 bones Sub-total: 126 bones
LIST OF BONES
Axial Skeleton 80 bones
Appendicular Skeleton 126 bones
Summing it up: 80 + 126 Total = 206 Bones
AXIAL SKELETON Forms the longitudinal axis of the body
Composed of : The Skull
Cranium Facial Bones The Hyoid Bone The Ossicles
The Ossicles of the Inner Ear Incus (Anvil) Malleus (Hammer) Stapes (Stirrup)
The Hyoid Bone The Vertabral Column (Spine)
Cervical Thoracic Lumbar Sacrum Coccyx
The Bony Thorax Sternum Ribs
APPENDICULAR SKELETON
Refers to the limbs or the appendages of the body. The Shoulder Girdle
Scapulae Clavicle
Bones of the Upper Limbs Arm Forearm Hands
Bones of the Pelvic Girdle Coxal Bones
Bones of the Lower Limbs Thigh Leg Feet
THE AXIAL SKELETON Forms the longitudinal axis of the body
Composed of : The Skull
Cranium Facial Bones
The Ossicles of the Inner Ear Incus (Anvil) Malleus (Hammer) Stapes (Stirrup)
The Hyoid Bone The Vertabral Column (Spine)
Cervical Thoracic Lumbar Sacrum Coccyx
The Bony Thorax Sternum Rib
The purpose of the axial skeleton (among other things) is to protect the body's most vital organs.
THE AXIAL SKELETON
The Skull Formed by two sets of bones
Cranium – encloses and protects brain tissues
Facial Bones – hold the eyes in an anterior position and allow the facial muscles to show our feelings
Normally made up of 22 bones in an adult 8 bones from the neurocranium
(brain case) 14 bones from the
splanchnocranium (facial bones)
THE AXIAL SKELETON Skull
CRANIUM Frontal Bone
Forms the forehead, the bony projections of the eyebrow and the superior part of each eye’s orbit
Parietal Bones (2) Forms most of the superior and lateral walls of
the cranium Sagittal suture – separates the parietal bones Coronal suture – separates the parietal and
frontal bones Temporal Bones (2)
Lie inferior to the parietal bones Separated by the squamous sutures
Occipital Bone Most posterior bone of the cranium Forms the floor and back wall of the skull Joins the parietal bones at the lamdoid suture
Sphenoid Bone Butterfly-shaped bone that spans the width of
the skull and forms part of the floor of the cranial cavity
Ethmoid Bone Irregularly shaped bone lying anterior to the
sphenoid Forms the roof of the nasal cavity and part of
the medial wall of the orbits
SKULL Temporal Bone
Significant bone markings: External acoustic meatus
A canal that leads to the eardrum and middle ear Styloid Process
Sharp, needlelike projection Inferior to the external acoustic meatus Attachment point for many neck muscles
Zygomatic Process Thin bridge of bone that joins with the cheek bone
Mastoid Process Rough projection posterior and inferior to the EAM Attachment site for some muscles of the neck
Jugular Foramen Junction of the occipital and temporal bones Allows passage of the jugular vein
Drains the brain Internal acoustic meatus
Transmits cranial nerves VII and VIII Carotid canal
Internal carotid artery runs Supplying blood to the brain
SKULL Occipital Bone
Significant Bone Markings: Foramen Magnum
“large hole” Surrounds the lower part of the brain Allows spinal chord to connect with the brain
Occipital condyles Rest on the first vertebra of the spinal
column
SKULL Sphenoid Bone
Significant Bony Markings Sella Turcica – “Turk’s saddle”
Small depression in the midline of the sphenoid Holds the Pituitary gland in place
Foramen Ovale Large oval opening in line with the posterior end
of the sella turcica Allows fibers of CN V to pass to the chewing
muscles of the lower jaw Optic Canal
Allows optic nerve to pass to the eye Superior Orbital Fissure
Allows passage of cranial nerves controlling eye movements
SKULL
Ethmoid Bone Significant Bony Landmarks
Crista Galli – “cock’s comb” Attachment of the outermost covering of the
brain Cribriform plates
Allow nerve fibers carrying impulses from the olfactory receptors of the nose reach the brain
Superior and middle nasal conchae Form part of the lateral walls of the nasal
cavity Increase the turbulence of air flowing through
the nasal passages
SKULL (LATERAL VIEW)
SKULL (CROSS SECTION SUPERIOR VIEW)
SKULL
SKULL
FACIAL BONES Palatine Bones
Lie posterior to the palatine process of the maxillae
Form the posterior part of the hard palate Failure to fuse results in cleft palate
Zygomatic Bones Cheek bones Form a portion of the laterl wall of the orbits
Lacrimal Bones Fingernail-sized bones forming part of the
medial part of the orbit Its groove serves as a passageway for tears
SKULL
FACIAL BONES Nasal bones
Small rectangular bones forming the bridge of the nose
Vomer Bone – “plow” Single bone in the median line of the nasal cavity Forms most of the nasal septum
Inferior Nasal Conchae Thin curved bones projecting from the lateral walls
of the nasal cavity Mandible
Lower jaw Largest and strongest bone of the face The horizontal part forms the chin The 2 upright bars of bones (rami) extend to
connect with the temporal bone Also has alveolar margin where the lower teeth lie
SKULL (ANTERIOR VIEW)
SKULL (INFERIOR VIEW)
THE HYOID BONE Only bone in the body
that does not articulate with any other bone
Suspended in the midneck region about 2cm above the larynx
Serves as movable base for the tongue
Attachment point for neck muscles that raise
Lower the larynx when we swallow or speak
THE HYOID BONE
FETAL SKULL
VERTEBRAL COLUMN (SPINE)
Serves as the axial support of the body Extends from the skull to the pelvis Surrounds and protects the spinal cord in
its central cavity Prevents shock to the head when we walk
or run consists of 26 irregular bones (vertebrae)
7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 1 (5 fused) sacrum 1 (4 fused) coccyx
Separated by intervertebral discs
VERTEBRAL COLUMN
(SPINE)
THE VERTEBRAE STRUCTURAL PATTERN
Common Features: Body or centrum
Disc-like weight bearing part Vertebral arch
Arch formed from the joining of all posterior extensions, the LAMINAE and PEDICLES
Vertebral foramen Canal through which the spinal cord passes
Transverse process Two lateral projections from the vertebral arch
Spinous process Single projection arising from the posterior
aspect of the vertebral arch The fused lamina
Superior and inferior articular processes Paired projections lateral to the vertebral
foramen Allows a vertebra to form joints with adjacent
vertebrae
THE VERTEBRAE
THE VERTEBRAE
Cervical Vertebrae Composed of 7 vertebrae Identified as C1 to C7 The first 2 vertebrae are different
They perform functions not shared by other cervical vertebrae
C1 – ATLAS No body Allows you to nod “yes”
C2 – AXIS Acts as pivot for the rotation of the atlas above
Odontoid process/dens – acts as pivot point Allows you to rotate your head from side to side to indicate “no”
C3 – C7 (typical vertebrae Smallest, lightest vertebrae Dual branched spinous process The transverse process contain openings
Vertebral arteries pass here on their way to the brain
CERVICAL VERTEBRAE
CERVICAL VERTEBRAE (ATLAS)
CERVICAL VERTEBRAE (AXIS)
CERVICAL VERTEBRAE (TYPICAL)
THORACIC VERTEBRAE
Composed of 12 vertebrae Identified as T1 to T12 All typical Has 2 costal facets on each side Long spinous process and hooks
sharply downward
THORACIC VERTEBRAE
THORACIC VERTEBRAE
LUMBAR VERTEBRAE
Consists of 5 typical vertebrae Identified as L1 to L5 Massive blocklike bodies Short, hatchet-shaped spinous
process Sturdiest of the vertebrae
LUMBAR VERTEBRAE
SACRUM
Formed by the fusion of 5 vertebrae Articulates to L5 superiorly Connects to coccyx inferiorly Wing-like ALAE articulate laterally to
the hip bones, forming the sacroiliac joints
Forms posterior wall of the pelvis
SACRUM
COCCYX
Formed from the fusion of 3 to 5 irregularly shaped vertebrae
The human “tailbone” A remnant of the tail that other
vertebrate animals have
COCCYX
BONY THORAX
Composed of the sternum, ribs, and thoracic vertebrae
Often called “thoracic cage”
Forms a protective, cone-shaped cage
BONY THORAX
STERNUM Breastbone Typical flat bone A result of fusion of
3 bones: Manubrium Body Xyphoid process
Attached to the first 7 pairs of ribs
STERNUM
Significant bony landmarks Jugular notch
Concave upper border of the manubrium Sternal angle
The manubrium and body meet Xiphisternal joint
The point where the body and xiphoid process fuse
BONY THORAX RIBS
12 Pairs of these form the wall of the bony thorax
All ribs articulate with the vertebral column posteriorly
Curved downward and toward the anterior body True Ribs
First 7 pairs attach directly to the sternum by costal cartilages
False Ribs The next 5 pairs Attached indirectly to the sternum Are not attached at all The last 2 pairs are called FLOATING RIBS
Do not have sternal attachments at all
RIB CAGE
RIBS
RIBS
APPENDICULAR SKELETONComposed of the 126
bonesLimbs (appendages)
Upper Lower
Pectoral and pelvic girdle Attaches the limbs to
the axial skeleton
APPENDICULAR SKELETONBones of the
Shoulder (Pectoral) GirdleScapula (2)Clavicle (2)
Bones of the Shoulder GirdleClavicle
CollarboneLong, slender, doubly
curved boneAttaches to the
manubrium mediallyAttaches to the scapula
laterallyHelps form the shoulder
jointActs as a brace to hold
arm away from the top of the thorax
Helps prevent shoulder dislocation
Bones of the Shoulder GirdleScapulae
Shoulder blades Large, flat, triangular often called “wings” Located at the dorsal
portion of the thorax Covers the area from the
2nd to the 7th rib Has 3 borders
Superior Lateral Medial
Has 3 angles Superior Lateral Inferior
ScapulaeSignificant Bony Markings
Coracoid process Origin for some muscles that move the arm
Acromion Point of the shoulder articulating with the lateral
end of the clavicleGlenoid Cavity
Articulates with the head of the humerus
Scapulae
Bones of the Upper LimbsForm foundations of the
Arm Humerus
Forearm Radius Ulna
Hand Carpals (8) Metacarpals (5) Phalanges (14)
Consists of 30 separate bones
ArmHumerus
Typical long bone Significant Markings:
Head Fits into the Glenoid Cavity
Greater and Lesser Tubercles Sites of muscle attachments
Deltoid tuberosity Attachment for the deltoid
muscle Radial Groove
Marks the course of the radial nerve
Trochlea and Capitulum Distal ends that articulates
with the bones of the forearm
ForearmConsists of 2 bones
Radius and Ulna Joins at the
radioulnar joints Connected along
their entire length by interosseous membrane
Hand Carpals (8)
Proximal Navicular/Scaphoid
Most frequently fractured Lunate
Frequently dislocated Triquetrium Pisiform
Pea bone Smallest carpal
Distal Greater Multangular/Trapezium Lesser Multangular/Trapezoid Capitate Hamate
Metacarpals (5) Phalanges (14)
Proximal phalanx Middle phalanx Distal phalanx
Except Thumb with 2 phalanges Proximal and distal Pollex
Bones of the Pelvic GirdlePelvic Girdle
Formed by two coxal bones
Commonly called hip bones
Bony pelvis Hip bones Sacrum Coccyx
Large and heavySecurely attached to the
axial skeletonMost important function:
Bearing weightProtects organs such as
the urinary bladder, reproductive organs
Bones of the Pelvic Girdle
Pelvic Girdle
Pelvic Grirdle
Pelvic Girdle
Bones of the Lower LimbCarry our total
body weightBones are much
thicker and stronger than the bones of the upper limbs
Bones of the Lower LimbThigh
Femur Thigh bone Heaviest Strongest
Bones of the Lower LimbLeg
Tibia Shin bone Larger More medial
Fibula Most slender bone
Bones of the Lower LimbFoot
Tarsals (7) Talus Calacaneus Navicular Cuneiform
Medial Intermediate Lateral
CuboidMetatarsals (5)Phalanges (14)