anatomy chapter 7. axis- center consists of the center bones of the body 80 bones 3 major regions:...
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axis- centerconsists of the center bones of the
body80 bones
3 major regions:skullvertebral columnthoracic cage
Axial skeleton
most complex structuremostly flat boneshas about 85 named openings22 bones, usu interlocked along suture lines
8 cranium bones14 facial bones
Skull
helmetencloses and protects the brain, provides areas for muscle attachment for head movements and chewing
held together by sutures- immovable joints
Cranium
1. frontal- forehead2. parietal- largest part (2)3. occipital-
external occipital protuberanceforamen magnumoccipital condyles
4. temporal (2)- Latin- temporum- time passing
external auditory meatusmastoid processstyloid 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 saddle6. ethmoid bone- forms most of bony area of nasal cavity & eye orbits
cribiform platescrista galli- cock’s comb
Facial bones14 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
1. Maxillaekeystone bone of the face
form upper jaw, roof of mouth, floors of orbits and nasal cavity
Vertebral Column~ 28” long in adults
26 irregular bones adults
infants 33 bones
separated by intervertebral discs
Cervical VertebraeC1 – atlas
nod yes; up and down m’ment
C2- axisshake no; side to side m’ment
7 vertebrae
Sacrum and Coccyxsacrum- 5 fused vertebrae
form base of column
coccyx- lowest part of column
4 fused bones
Thoracic Cageincludes ribs,
thoracic vetebrae, sternum, costal cartilages
fxn: support pectoral girdle, protect viscera, aid in breathing
12 pairs (usually) join to a thoracic vertebra1st 7 ribs are TRUE RIBS- join sternum directly by their costal cartilages
next 5 pairs are FALSE RIBS- cartilage doesn’t reach sternum diriectly
next 2 (3) pairs are FLOATING RIBS- no cartilaginous attachment to sternum
Ribs
process of bone developingbones form by replacing existing connective tissue in either of 2 ways:
1. intramembranous ossification- formation of bone directly on or within fibrous membranes
Ossification
simplest, most direct type of bone development
osteoblasts form bone tissueskull & clavicles formed this way
replacement of hyaline cartilage shapes by bone tissue
endo= within chondro= cartilage
2. endochondral ossification