Anatomy Chapter 7

axis- center consists of the center bones of the body 80 bones 3 major regions: skull vertebral column thoracic cage

most complex structure mostly flat bones has about 85 named openings 22 bones, usu interlocked along suture lines 8 cranium bones 14 facial bones

helmet encloses and protects the brain, provides areas for muscle attachment for head movements and chewing held together by sutures- immovable joints

8 bones

1. frontal- forehead 2. parietal- largest part (2) 3. occipital- external occipital protuberance foramen magnum occipital condyles 4. temporal (2)- Latin- temporum- time passing external auditory meatus mastoid process styloid process- (stake-like) zygomatic process

5. sphenoid- (spheno-wedge) helps form base of cranium, sides of skull, floors and sides of orbits; keystone sella turcica- Turk’s saddle 6. ethmoid bone- forms most of bony area of nasal cavity & eye orbits cribiform plates crista galli- cock’s comb

14 bones- 13 immovable; 1 movable Fxn: form basic shape of face, provide attachment for muscles, contain cavities for special sense organs, provide openings for air & food, & secure teeth

keystone bone of the face form upper jaw, roof of mouth, floors of orbits and nasal cavity

form cheekbones

horseshoe shaped body

fxn: warm and humidify air lighten skull enhance resonance of voice sinus infections

aka soft spot allows for movement through birth canal close up by 2 years of age

~ 28” long in adults 26 irregular bones adults infants 33 bones separated by intervertebral discs

C1 – atlas nod yes; up and down m’ment C2- axis shake no; side to side m’ment 7 vertebrae

Larger than cervical Articulate with ribs 12 vertebrae

biggest vertebrae bears most of body’s weight small of back 5 vertebrae

sacrum- 5 fused vertebrae form base of column coccyx- lowest part of column 4 fused bones

includes ribs, thoracic vetebrae, sternum, costal cartilages fxn: support pectoral girdle, protect viscera, aid in breathing

12 pairs (usually) join to a thoracic vertebra 1 st 7 ribs are TRUE RIBS- join sternum directly by their costal cartilages next 5 pairs are FALSE RIBS- cartilage doesn’t reach sternum directly next 2 (3) pairs are FLOATING RIBS- no cartilaginous attachment to sternum

usu break at greatest curvature middle ribs commonly fractured

aka breastbone ~ 6” long xyphoid process doesn’t completely ossify until about 40 years old

Only bone in body that doesn’t articulate w/ other bones Enables us to talk

process of bone developing bones form by replacing existing connective tissue in either of 2 ways: 1. intramembranous ossification- formation of bone directly on or within fibrous membranes

simplest, most direct type of bone development osteoblasts form bone tissue skull & clavicles formed this way

replacement of hyaline cartilage shapes by bone tissue endo= withinchondro= cartilage

growth takes place at the epiphyseal plates on the long bones

most bones of body form this way more complex method by age 25 all bones are ossified clavicle- last bone to stop growing bone REMODELING occurs continuously thru-out life

Skull: mastoid process, size of skull, forehead, weight Limbs

Pelvic cavity: wider in females, pubic arch > 90 o

aka articulation bind parts of skeletal system make bone growth possible allow parts of skeleton to change shape during childbirth enable body to move during muscle contraction 230 joints in body

3 classifications: immovable slightly movable freely movable

basically NO movement bones lie in close contact w/ each other ex: sutures in skull

hyaline cartilage connects bones slightly movable

freely movable synovial fluid reduces friction joint capsule menisci- bursae 6 types

wider range of motion hip shoulder

condyle fits into elliptical cavity variety of m’ments in different planes; rotational m’ment not allowed

most joints in wrists & ankles allow sliding & twisting motion

cylindrical bone rotates rotation around central axis

allows for flexion and extension

variety of m’ment