sign in sign up
<<
Home , Cartilage, Condyle, Coracoid, Diaphysis, Endosteum, Medullary cavity

Skeletal System Skeletal , and are tightly joined to form a strong, flexible framework each individual is a separate of the skeletal system bone is active tissue: !5-7% bone mass/week ~270 bones (organs) of the Skeletal System

Functions of Skeletal System: with age the number decreases as bones fuse 1. Support by adulthood the number is 206 (typical) strong and relatively light; 20% body weight 2. Movement even this number varies due to varying numbers framework on which muscles act of minor bones: act as levers and pivots sesamoid bones – small rounded bones that form within 3. Protection in response to stress brain, , heart, eg. kneecap (), in knuckles 4. Mineral storage (electrolyte balance 99% of body’s calcium is in bone tissue wormian bones –bones that form within the sutures of (1200-1400g vs <1.5g in blood, rest in cells) skull also stores phosphate each skeletal organ is composed of many kinds of 5. Hemopoiesis tissues: formation bone (=osseous tissue) 6. Detoxification cartilage bone tissue removes heavy metals and other foreign materials fibrous connective tissues from blood blood (in blood vessels) can later release these materials more slowly for excretion nervous tissue but this can also have bad consequences General Shapes of Bones

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 1 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 2

bones can be categorized according to their general the general structure of a typical longbone: shape:

1. long: cylindrical, longer than wide

articular cartilage rigid levers for muscle actions eg crowbars eg. , legs, , 2. short: length nearly equal width limited motion, gliding if any

epiphysis eg. carpals, tarsals, patella

3. flat: thin sheets of bone tissue epiphyses enclose and protect organs large surface area for muscle attachment and pivot

broad surfaces for muscle attachments spongy bone with trabeculae;

eg. , ribs, most bones, , os coxa contains red marrow (=hemopoietic tissues)

4. irregular: elaborate shapes different from above ! produces blood cells in delicate mesh of reticular tissues eg. vertebrae, sphenoid, ethmoid in adults red marrow is limited to vertebrae, sternum, ribs, pectoral and pelvic girdles, proximal of Bone Structure and bones have outer shell of compact bone with age, red marrow is replaced by yellow marrow usually encloses more loosely organized bone tissue articular cartilage = spongy (=cancellous) bone on surface of epiphyses

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 3 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 4 resilient cushion of highly organized arrangement of matrix and cells diaphysis

lacunae w thick compact bone but light; hollow ! medullary cavity & canaliculi

medullary cavity lamellae

yellow marrow – fat (adipose) storage

“fat at the center of a ham bone” perforating canals (Volkmann canals) interconnect the haversian canals in event of severe anemia, yellow marrow can transform back into red marrow to make blood cells periosteum provides life support system for periosteum bone cells

white fibrous continuous with tendons penetrates bone – welds blood vessels to bone blood vessels penetrate bone and connect with those in haversian canals endosteum fibrous CT that lines medullary cavity B. cartilage

Microscopic Structure () resembles bone: large amount of matrix A. bone: lots of fibers

connective tissue; contains cells and matrix differs: firm flexible gel is not calcified (hardened) bone cells = no haversian canal system no direct blood supply matrix predominates; ~ 1/3rd organic and ! nutrients and O2 by 2/3rd’s inorganic all bone starts out as cartilage matrix contains lots of collagen fibers

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 5 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 6

in bone the matrix is hardened (= ossified) by Anatomy of Skeletal System calcification (or mineralization)

microscopic structure of cartilage: Bone Markings: any bump, hole, ridge, etc on each bone; eg.: in lacunae Foramen: opening in bone – passageway for and blood vessels kinds of cartilage: (all similar matrix with lots of collagen Fossa: shallow depression – eg a socket into which another bone fibers; differ in other fibers) articulates Sinus: internal cavity in a bone 1. hyaline most common : rounded bump that articulates with another bone eg. covers articular surfaces of , of ribs, rings of tracheae, nose Tuberosity: large rough bump – point of attachment for muscle

2. fibrous Spine: sharp slender process mostly collagen fibers eg. discs between vertebrae, pubic two main subdivisions of skeletal system:

3. elastic axial : skull, vertebral column, also has elastic fibers eg. external , eustacean tube appendicular: arms and legs and girdles

The Axial

A. Skull

most complex part of the skeleton

consists of facial and cranial bones

most bones are paired, not all Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 7 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 8 in 4 of the bones making up the face bones joined at sutures in life lined with mucous membrane to form sinuses

1. Fontanels lighten bone, warm and moisten air

of skull begins in about 3rd month of 6 sinuses: fetal development frontal -2 maxillary -2 ethmoid -1 not completed at birth!bones have not yet fused sphenoid -1

gaps = fontanels Examples of Paired Skull Bones: frontal (anterior) occipital (posterior) 5. 2 sphenoid 2 mastoid cheek bones, upper teeth cemented to these bones at this stage skull is covered by tough membrane for protection hard palate: palatine process and palatine bones normally, bones grow together and fuse to form solid case around brain cleft palate ! when bones of palatine process of maxilla bones do not fuse properly 3. Skull Cavities not only cosmetic effect inside of skull contains several significant cavities: can lead to serious respiratory and feeding problems in babies and small children today, fairly easily corrected cranial cavity – largest (adult – 1,300 ml); part of dorsal body cavity orbits – eye sockets 6. Temporal Bone

external auditory meatus - opening to ear canal leads to middle ear chamber buccal cavity ear : middle and inner ear cavities = hammer 4. Paranasal Sinuses = anvil = stirrup

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 9 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 10

7. = lower very delicate and easily damaged by sharp upward blow to the nose largest, strongest bone of face articulates at temporal bone can drive bone fragments through the cribriform plate into the or brain itself

Examples of Unpaired Skull Bones: can also shear off olfactory nerves! loses of smell

8. 11. – single “U” shaped bone in just below mandible foramen magnum - large opening in base through which passes suspended from styloid process of temporal bone

occipital - articulation of vertebral column only major bone in body that doesn’t directly articulate with other bones 9. – irregular, unpaired bone serves as point of attachment for tongue and several other muscles resembles bat or butterfly;

“keystone” in floor of cranium B. Vertebral Column

! anchors many of the bones of cranium main axis of body contains sinuses flexible rather than rigid sella turcica – depression for the permits foreward, backward, and some sideways 10. ethmoid – irregular, unpaired bone movement honeycomed with sinuses divided into 5 regions: cribiform plate – perforated with openings which cervical allow olfactory nerves to pass thoracic lumbar nasal conchae – passageways for air; filtering, sacral warming, moistening coccygeal

crista galli – attachment of meninges all but last two are similar in structure: Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 11 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 12 body sacroiliac – lots of stress spinous process vertebral foramen Coccyx (4-5, some fused): transverse process superior and inferior articular process intervertebral foramen between each pair tailbone separated by intervertebral discs painful if broken

Cervical (7): sometimes blocks birth canal, must be broken

have transverse foramena C. Ribcage 1s t and 2nd are highly modified for movement: manubrium – holds up sternum body (=gladiolus) no body or spinous process “yes” movement of head ribs: most joined to sternum by costal axis -- dens (odontoid process) – forms pivot “no” movement true ribs (7prs)

Thoracic (12): false ribs (5 prs) include floating ribs (2prs) distinguished by facets smooth areas for articulation of ribs

each rib articulates at two places one on body of vertebrae one on transverse process

Lumbar (5):

short and thick spinous processes

modified for attachment of powerful back muscles

Sacrum (5 fused):

triangular bone formed from fused vertebrae

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 13 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 14

Appendicular Skeleton 3. Forearm:

A. Upper Extremeties very mobile; adds to of consists of two bones: & (=pectoral girdle) upper and lower they are attached along their length by and hand ulna: 1. Pectoral Girdle: main forearm bone firmly joined to humerous at scapula & large process = olecranon process, extends behind elbow joint only attached to trunk by 1 joint (between sternum and clavicle) acts as lever for muscles that extends forearm

th scapula is very moveable – acts as almost a 4 segment radius: of limb more moveable of two scapula rides freely and is attached by muscles and can revolve around ulna to twist lower arm and hand tendons to ribs but not by bone to bone joint

extensive flat areas of scapula are used as origins for 4. Hand: arm muscles and trunk muscles attached by muscles mainly to radius provides great flexibility clavicle is the most frequently broken bone in the body, sometimes even during birth large # of rounded bones (carpals) provide flexibility

2. Upper Arm: carpals allow movement in all directions metacarpals also rounded for flexibility Humerus: longest and largest bone of arm phalanges, not rounded, simple hinges for grasping loosely articulates with scapula by head – glenoid cavity

large processes of scapula, acromium and coracoid

!have muscles which help to hold in place

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 15 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 16 B. Lower Extremeties : anterior joint of fibrous cartilage

in women before birth it softens to allow expansion of number and arrangement of bones in the lower limb birth canal are similar to those of the as bipedal animals the must support most of the body weight in the lower limb they are adapted for weight bearing and locomotion, not dexterity !viscera bear down on pelvic floor

! pelvis is funnel shaped; yet must remain large enough pelvic girdle (pelvis, 2 coxal bones, sacrum, coccyx) for the birth canal lower leg pelvis is easiest part of skeleton to distinguish between sexes feet 2. Upper Leg = Thigh 1. Pelvic Girdle made up of single bone = femur; largest bone in body forms large basin of bone head fits in large deep socket = acetabulum of pelvis !receptacle for many internal organs great strength, less flexibility than humerous origin of thigh muscles and trunk muscles

rigid connection to ; strength, not flexibility kneecap = patella;

large flaring portion = false pelvis a = bones found where tension or pressure exists; eg and large smaller actual opening = true pelvis in tendons at joint; does not articulate directly with !actual space child must fit through in women any other bone

pelvis consists of a pair of innominate bones (= os coxae) acts as kind of a bearing that articulate with sacrum !allows to slide smoothly across knee joint

each innominate is produced by fusion of three bones: if patella is lost through accident or injury get ~30% loss of mobility and strength due to > friction ilium – upper, fan shaped ischium – bottom 3. Lower Leg pubis – front

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 17 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 18

consists of two bones: and

tibia (=shinbone) Articulations

main bone, articulates with both femur and Articulations = joints between bones !more strength, less mobility fibula hold bones together while usually allowing some movement small, offers extra support for lower leg and foot

4. Foot can be classified by:

like hand, made of many bones 1. degree of movement

thick angular bones; must support all the weight of the body 2. structure of the joint arches: strung with ligaments to provide double arches = shock absorbers Degree of Movement

arches also furnish more supporting strength than any other type of construction !more stability Synarthroses (=”joined together”, joint)

if ligaments and muscles weaken, arches are lost !immoveable = flatfootedness = fallen arches,

! more difficult walking, foot pain, back pain Amphiarthroses (=on both sides, joint)

high heals redistribute the weight of foot!throw it !slightly moveable foreward; ends of metatarsals bear most weight Diarthroses (through a joining) !sore feet !freely moveable

Structure of the Joint

Fibrous Joints

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 19 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 20 articular surface of both bones Examples of the 3 kinds of articulations

joined by fibrous connective tissue 1. Immoveable (Fibrous) Joints

Cartilaginous Joints eg. sutures – only in skull articular surface joined by some kind of cartilage (eg. fibrous or hyaline) eg. gomphoses -teeth in socket Synovial Joints eg. syndesmoses

articulation is surrounded by - fibrous bands between two bones and - distal tibiofibular joint joint capsule articular cartilage 2. Slightly Moveable (Cartilaginous) joint cavity synovial membrane eg. symphyses periosteum - pad or disc

In general structure is correlated with function: -midline of body -symphysis pubis therefore, three major kinds of joints: -intervertebral discs

1. immoveable ~ fibrous eg. synchondroses

2. slightly moveable ~ cartilaginous -hyaline cartilage joins two bones

-epiphyseal discs; temporary 3. freely moveable ~ synovial -costal cartilage between ribs and sternum

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 21 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 22

3. Freely Moveable (Synovial) !slow to repair

most body articulations tendons – specialized structures that attach provide for many different kinds of motion: muscle to bone across joints

eg. uniaxial often enclosed by tendon sheath (fingers, toes, elbow) ligaments – bind bones together across joints pivot joints (head, radius at hand)

eg. biaxial more elastic than tendons

condyloid joints (metacarpals-phalanges hold joints in place

saddle joints (metacarpal-thumb) limit their range of motion eg. multiaxial Bursa gliding joint (carpals, tarsals)

ball and socket joints (shoulder, ) synovial sacs spaced around joints between tendons or ligaments Includes tendons and ligaments cushion ! reduce friction both composed mainly of fibrous connective tissue Exercise and Synovial Joints

synovial fluid is warmed by exercise and becomes thinner consist of parallel strands of collagen fibers !this is more easily absorbed by articular cartilage continuous with periosteum and embedded in !provides more effective cushion against compression bone this warmup and compression also helps to distribute nutrients rarely break but tear away from bone to cartilage cells (nonvascular tissue) and squeeze out metabolic wastes

when mature have few cells ! warm up is good for you Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 23 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 24 Skeletal Physiology Physiology of Bone Composition of Bone bone is active tissue: bone is the densest tissue in the body ! only 20% water !5-7% bone mass/week mature haversian canal systems are replaced up to 10x’s bone has a grain just like wood: during a lifetime

grain runs longitudinally for greatest strength !equiv. of skeletal mass is replaced every 7 years bone tissue consists of cells and matrix: most calcium in body is contained in teeth and skeleton

cells: =osteocytes ! acts as a mineral reservoir, esp for calcium, and phosphate cells that secrete the matrix calcium is used in body for: matrix: muscle contractions rd impulses 2/3 mineral salts (bone only) synapses calcium & phosphorus heart beat secretions blood clotting (CaPO4, CaOH, CaCO3) also Mg, Na, K cofactors for enzymes

tends to accumulate metals:lead & radium a supply of calcium must be constantly available for all ! bone , leukemia these activities

rd 1/3 collagen and (cartilage and blood calcium homeostasis is maintained by bone) dissolving or depositing bones via osteocytes

mixture of organic and inorganic components allow cells = osteocytes ( in lacunae) bone to be strong without being brittle

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 25 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 26

two kinds of bone cells: epiphyseal cartilage disappears when bone has bone forming cells completed its growth (in length)

also works alongside to rework bone Bone Maintenance and Remodeling osteoclasts bone destroying cells the skeletal system is strongest in early adulthood very large cells produced by cell fusions contain up to 300 nuclei bones continue to grow and remodel themselves amoeboid movement throughout life

wraps around small section of bone bone growth in diameter occurs by combined action of secretes enzyme to digest it osteoblasts and osteoclasts

Bone Formation even after bone growth has stopped, osteoblasts and osteoclasts continue working parts of skeleton begin to form in 1st few weeks of development in adult these opposing processes balance each other out so bone neither grows nor shrinks begins in fetus as cartilage template bone destruction is not always a pathological Ossification = conversion of cartilage or other process: connective tissueinto bone

rd a. bones constantly adapting to stresses in longbones ossificaton begins 3 month of reaction to mechanical stresses development tension regions + chg compresed regions – chg centers of ossification in longbones: affects PTH activity

begins in diaphysis strengthens weak areas

at birth additional centers in epiphyses b. old bone removed to reduce bulk

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 27 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 28 Effects of Aging on Skeletal System c. minerals are added or removed from reservoir as Calcium is metabolized Skeletal Changes from Childhood to Adult:

++ 99% of body’s Ca is in bone A. infancy & childhood (1200-1400g vs 1.5g in blood)

two hormones involved - antagonists change size, proportion,

PTH growth in length is cartilage of epiphyseal disc

!stimulates bone destruction (osteoclasts) growing faster than ossification proceeds

Calcitonin plays major role

!stimulates bone formation (osteoblasts) ! stimulates cartilage

Ca++ deficiency: thyroid hormone

severe neuromuscular problems hyperexcitability ! proper proportions loss of function head becomes proportionately smaller Ca++ excess: facial bones more prominent thorax more elliptical Calcium deposits in blood vessels, pelvis larger and wide kidneys and soft organs legs proportionately longer vertebral column develops two additional curves (already had thoracic and pelvic curves) cervical curve ~3mo; lifts head lumber ~1 yr; standing, walking

B. Puberty

sex hormones (estrogen & testosterone) stimulate

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 29 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 30

! bone become brittle ossification shaggy margins, spurs, joint problems ! epiphyseal closure cartilage keeps growing: big facial features develop rapidly

also produce masculinizing and feminizing features of skeleton

male – deep and funnel shaped; whole skeleton larger and heavier

female – shallow, broader and flaring

C. Adulthood:

Bone maintenance and remodeling

bone destruction is not always a pathological process:

a. bones constantly adapting to stresses

b. old bone removed to reduce bulk

c. minerals are added or removed from reservoir as calcium is metabolized

D. Old Age

reabsorption outweighs growth

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 31 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 32 Disorders of Skeletal System 2. Vertebral curvature

1. Fractures normally spine has two “S” shaped curves

repairs more slowly than skin; up to 6 months provides flexibility and resilient support

a. clot (hematoma) formation several types including:

hours scoliosis – abnormal lateral curvature broken blood vessels, damaged tissues, bone cells die may appear spontaneously or be result of polio, rickets or TB b. soft callus (fibrocartilage) 3. Osteoporosis days growth of new capillaries bones lose mass and become more brittle disposal of dead tissue group of diseases in which bone reabsorption c. bony callus outpaces bone deposition

weeks affects entire skeleton but esp spongy bone tissue grows around area and replaces spongy bone of vertebrae and neck of femur fibrocartilage join two pieces firmly together esp in post menopausal women

d. remodeling sex hormones stim bone deposition, months decrease activity dead portions of original area reabsorbed compact bone replaces spongy bone menopause – sharp reduction in sex hormones ends are remodeled to blend in usually thickened area remains esp post menopausal women (esp caucasian women) misset bones may heal crooked but weight bearing bones usually reassume proper shape by 70 yrs the average white woman has lost 30% of her bone elec current speeds calcification and repair mass (some up to 50%)

not as drastic in men new synthetic materials may soon be useful in replacing missing bone loss begins ~60 yrs and seldom exceeds 25% loss bone also bone grafts smoking also reduces estrogen levels Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 33 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 34

bony spurs may form as cartilage wears away !deform joint low body fat reduces estrogen production by ovaries in young interfere with movement, pain female runners and dancers 6. Rheumatoid Disease most serious consequence is pathologic fractures esp in hip, wrist and vertebral column far more severe than OA also, as bones become less dense they compress like is an autoimmune attack against synovial membrane marshmallows inflammation of synovial membranes and degeneration of cartilage synovial membranes fill with abnormal tissue growth = ! results in kyphosis ! exaggerated thoracic curve (widow’s hump, dowager’s hump) granulation tissue may erode articular cartilage, bones and ligaments suggestions: mainly small joints of body; , need good bone mass by 35 or 40 tends to flare up and subside periodically plenty of weight bearing exercise, esp before menopause affects women far more than men good calcium uptake (850-1000 mg/d) early in life, esp 25-40 typically begins between age 30 – 40 fluoridated water helps harden bones no cure, but can be slowed with steroids, cortisone, etc don’t smoke hormone replacement therapy only slows loss, doesn’t replace 7. lost bone -No longer recommended, too dangerous any infection of bone, cartilage or periosteum localized or general 4. Rickets usually bacterial

childhood disease: bowed legs, deformed pelvis, 8. Ruptured (herneated) disc due to Vit D (or Ca++) deficiency during growing years body unable to absorb calcium from intestine intervertebral discs pad vertebrae reduces calcification – bones stay soft with age outer layer thins and cracks; inner layers less firm extra pressure can cause rupture 5. = herneated disc: pain, numbness, partial paralysis

most common age change is degeneration of joints 9. Gout =wear and tear rarely occurs before age 40; affects 85% of those over 70 group of diseases characterized by elevated uric acid in blood as joints age get gradual softening and loss of articular cartilage forms sodium urate crystals in synovial fluid causing severe pain bone formation at margin of articular cartilage exacerbated by alcoholism as cartilage becomes roughened by wear, joint movements may be accompanied by crunching or cracking sounds (=) affects especially fingers, intervertebral joints, and 10. Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 35 Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 36 inflammation of bursal sacs around joints fills with fluid usually caused by blow or friction =“housemaids knee” =“water on the knee”

11. Tendonitis

inflammation, usually due to overuse

12. Achondroplastic

spontaneous mutation of genes, not necessarily from parents long bones of limbs stop growing in childhood while growth of other bones is not affected ! results in short stature but normal sized head and trunk not same as pituitary dwarfism, only certain cartilage cells are affected

13. Polydactyly & Syndactyly

too many or too few fingers and toes

Human Anatomy & Physiology: Skeletal System; Ziser, Lecture Notes, 2010.4 37