Survey of Anatomy and Physiology Chapter 6

The Skeletal System:The Framework

6

Skeleton’s FunctionSkeleton’s Function

• Provides support and structure• Allows us to move• Protects soft body parts• Produces blood cells• Stores minerals and fats

Bones are primary components

of the skeleton

Although composed of nonliving minerals such as calcium and phosphorus, bones are very much alive, constantly building and repairing themselves

Bones-IntroBones-Intro

The word skeleton comes from

Greek word meaning "dried-up body"

Bones-IntroBones-Intro

Classified according to their shape

Long bones: longer than they are wide and can be found in arms and legs

General Bone General Bone ClassificationsClassifications


Short bones: fairly equal in width and length and found mostly in wrists and ankles



Flat bones: thinner and can be either flat or curved; plate like in nature and would include skull, ribs, and breastbone (sternum)



Irregular bones: like parts of jigsaw puzzle, odd in shape; include hip bones and vertebrae


Figure 6-1

Various bone shapes.

Periosteum (around bone)

Tough and fibrous connective tissue covering bone

Contains blood vessels, which transport blood and nutrients to nurture bone cells, lymph vessels, and nerves

Acts as anchor points for ligaments and tendons

Bone AnatomyBone Anatomy


Epiphysis and diaphysis Epiphysis: bone end Diaphysis: region between

or "running through" two epiphyses; also called shaft

Hollow region in diaphysis (medullary cavity or canal) acts as storage area for bone marrow

Bone marrow

Red marrow: makes blood cells

Yellow marrow: high fat content; can convert to red marrow in emergency


Figure 6-2Basic bone anatomy.

• Periosteum• Epiphysis• Diaphysis• Medullary• Red Marrow• Yellow Marrow

PA/Instructor Asks:

A. ErythropoetinB. ElectrophoresisC. HemorrhageD. Hemopoiesis

Bone TissueBone Tissue

Bone TissueBone Tissue

Each unit or osteon

has mature bone cells (osteocytes) forming concentric circles around blood vessels

Area around osteocyte filled with protein fibers, calcium, and other minerals

Bone Tissue-CompactBone Tissue-Compact

Osteons run

parallel to each other; blood vessels laterally connect with them to ensure there is sufficient oxygen and nutrients for bone cells

Bone Tissue-CompactBone Tissue-Compact

Trabeculae are

bars and plates with holes in the middle to make the bone lighter and create space for marrow to form red blood cells

Bone Tissue-SpongyBone Tissue-Spongy

Trabeculae

Figure 6-3Comparison of compact and

spongy bone.Compact•Osteons with•Osteophytes•Connected by blood and lymph vessels

Spongy•Trabeculae formed by bars and plates•Hollow to give space for marrow

Bone is not perfectly

smooth; has variety of projections, bumps, and depressions Projections act as

points of attachment for muscles, ligaments, or tendons

Surface Structure of Surface Structure of BonesBones

Grooves and depressions act as pathways

for nerves and blood vessels

Surface Structure of Surface Structure of BonesBones

Ossification (osteogenesis): formation of

bone in the body Bones grow longitudinally to develop

lengthen and horizontally (wider and thicker) so they can efficiently support body weight and any other weight we support

Bone Growth and Bone Growth and Repair-OsteogenesisRepair-Osteogenesis

Osteoprogenitor cells: nonspecialized cells

found in periosteum, endosteum, and central canal of compact bones; can turn into other types of cells as needed

Non-Specialized CellsNon-Specialized Cells

Bone Growth and Bone Growth and Repair-Cell TypesRepair-Cell Types

Bone Growth Bone Growth and Repairand Repair

Osteoblasts actually form bone and secrete a matrix of calcium and phosphate

Bone Growth and Bone Growth and RepairRepair

Osteocytes mature bone cells that started as osteoblasts; osteoblasts surround themselves

with matrix of calcium that helps them become mature osteocytes

Osteoclasts: believed to originate from type

of white blood cell called monocyte found in red bone marrow; job is to tear down bone material and help move calcium and phosphate into the blood


FOUR Cells of Bone Growth

PA/Instructor Asks:PA/Instructor Asks:

A. OsteoblastsB. OsteoclastsC. OsteogenitorD. Osteoporosis

Bone development and growth begins in the

womb through intramembranous and endochondral ossification

Bone Growth Bone Growth and Repairand Repair

Watch video “Skeletal System Bone Formation”

http://www.youtube.com/watch?v=PIT8zIWmSiI


Figure 6-4Endochondral ossification of

long bone.

• Begins before birth• Periosteum surrounds the

“cartilage bone”

• Cartilage breaks down and osteoblasts create spongy bone in primary ossification region


long bone.

• Meanwhile other osteoblasts form compact bone under periosteum.

• Osteoclasts then break down the spongy bone of diaphysis (shaft) to create medullary (middle) of bone


long bone.

Epiphyseal plate is thin

band of cartilage that

forms between primary and secondary ossification

centers

Epiphyseal plate (growth plate)exists as

long as bones need to lengthen and widen


PA/Instructor Asks:PA/Instructor Asks:

A. CalciumB. Vitamin DC. FluorideD. Caffeine

*Read “Osteoporosis on Page 122

Figure 6-5A normal bone compared to an

osteoporotic bone.

Special form of dense connective tissue

that can withstand fair amount of flexing, tension, and pressure

CartilageCartilage

Flexible part of nose and ears are cartilage

CartilageCartilage

Makes flexible connection

between bones, as between breastbone and ribs, allowing chest to flex during deep breathing

CartilageCartilage

Acts as cushion

between bones; articular cartilage located on ends of bones and acts as shock absorber,

preventing ends from grinding together when you move

CartilageCartilage

Figure 6-6Articular cartilage and synovial joint.

At this location, a small sac, called bursa, secretes lubricant called synovial fluid

Joints can wear out and become inflamed

despite all this protection, resulting

in arthritis or osteoarthritis

Articulation/JointsArticulation/Joints

When two or more bones join together they form a

joint or articulation

When two or more bones join together they form a

joint or articulation

Ligaments: tough, whitish bands that connect

from bone to bone; can withstand heavy stress

Joints and LigamentsJoints and Ligaments

Tendons are cordlike structures that attach

muscle to bone

Joints and TendonsJoints and Tendons

Types of JointsTypes of Joints

Types of JointsTypes of Joints

Figure 6-7Types of Synovial joints.

Hinge: movement in ONE direction; knee and elbowBall & Socket: lots of movement; shoulder and hipPivot: rotation only is possible; neck or radius/ulnarEllipsoid joint: two areas of movement through same bone; wrist, knuckles

Figure 6-7Types of Synovial joints.

Gliding: flat & platelike that slide black and forth; scapula, wrists and ankles

Saddle: bone shaped like saddle sits over another like a horse; 1st metacarpal or thumb or the carpal bone

Figure 6-8Classification of joint movements.

Hyperextension: joint forced to straighten beyond its normal limitsAbduction: moving away from body's midlineAdduction: moving toward midline of bodyInversion: turning foot inward toward other footEversion: turning foot outward away from opposing foot


Supination: turning hand palm upPronation: turning hand palm downCircumduction: combination of movements in the circular arm movement of a pitcherProtraction: movement of part forwardRetraction: motion of drawing part backwardRotation: when bone "spins" on its axis


Flexion: bending a joint and decreasing angle between involved bonesExtension: straightening a joint; angle between involved bones increases Plantar flexion: pointing toes down Dorsiflexion: bending foot up toward the leg

Figure 6-9The anterior and posterior

human skeleton.

Axial skeleton (80)•thorax,•spinal column,•hyoid bone,•bones of middle ear,•SkullAppendicular (126)•Arms• legs• hips•shoulder

Figure 6-10Bones of the skull.

Protects and houses brain; has openings

needed for sensory organs (eyes, nose, and ears)

Contains mouth, common passageway for both

respiratory and digestive systems

Fibrous cartilage allows for some flexibility of

bones surrounding the brain

Figure 6-10 (continued)Bones of the skull.

Figure 6-10 (continued)Bones of the skull.

Figure 6-11The bony thorax.

The Bones of chest form thoracic "cage" that provides support and protection for heart,

lungs, and great blood vessels

Figure 6-11The bony thorax.

Cage is flexible due to cartilaginous connections that allow for movement during the

process of breathing

Sternum (breastbone) is location for performing chest compressions during

CPR, compressing heart between sternum and bones of vertebrae

The Bony ThoraxThe Bony Thorax

Figure 6-12The spinal column.

Also called vertebral column; super highway for

information traveling to and from the central nervous system

7 cervical vertebrae

in neck area 12 thoracic vertebrae

in upper back 5 lumbar vertebrae in

lower back 5 sacral vertebrae

midbuttock region 1 tailbone or coccyx is

3-5 small bones fused

The Spinal ColumnThe Spinal Column

At birth, vertebral column concave to front,

like a fetal position (primary curvature) Curvature changes as infant learns to hold its

head up, as well as starts to walk, curving in opposite direction


From two years onward,

vertebral column develops secondary curvature in neck, primary curvature in

upper back, secondary curvature in lower

back, primary curvature in midbuttocks and

tailbone regions


Figure 6-13Spinal disfigurements compared

to healthy spinal curves.

Figure 6-14Bones of the upper and lower

extremities.

Appendicular region consists of arms and legsThese areas perform most of the body movement, making them more vulnerable to sport-related injuries

Figure 6-14Bones of the upper and lower

extremities.

Pelvic girdle different for women than menWomen have greater pubic angle, which

facilitates childbirth, and broad girdle to

support extra weight of child

Pelvis consists of: ilium, ischium, pubis

Fracture is any break in a bone Types of fractures

Simple (closed): break without puncture to skin Compound (open): fracture in which bone has

been pushed through skin Hairline: fine fracture that does not completely

break or displace bone (looks like hair on x-ray)

Pathology Connection: Bone Pathology Connection: Bone Fractures and HealingFractures and Healing

Types of fractures

Greenstick: incomplete breaks, more common in children

Comminuted: when bone has been fragmented or splintered


Compound or open fractures are

particularly nasty because deep tissue has potential to be exposed to bacteria once bone is set into place; chance for infection in addition to break is increased


Bones take several weeks to heal; can only

heal normally if ends of bones are touching If bones are not touching (poorly aligned),

bone must be set (reduced) Traction may be used to treat fractures of

long bones


Watch video “Fracture Healing”http://www.youtube.com/watch?v=TYNGyZrUXEk

A somewhat frail 76-year-old female visits her

physician's office for an annual check-up. Her social history shows she smokes a pack of cigarettes a day and is a heavy coffee drinker.

Case StudyCase Study

She has had several fractured bones in the

last five years that required medical attention. During initial examination, measurements show that the patient has lost approximately an inch of height over the past year. She has also lost several pounds but states she still wears the same size clothes.


What possible bone disease do you think she

is exhibiting? Describe the bone changes in this condition on

a macro and cellular level (page 122) What treatments and/or lifestyle changes

would you suggest?


Health & Medicine

Survey of Anatomy and Physiology Chapter 6