skeletal system axial skeleton
Post on 24-Feb-2016
26 Views
Preview:
DESCRIPTION
TRANSCRIPT
AnatomyChapter 7
Skeletal SystemAxial Skeleton
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
8 bones
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
Frontal Occipital
Temporal
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
Sphenoid
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
Cleft palate
2. Zygomatic bonesform cheekbones
3. Mandiblehorseshoe shaped body
Sinusesfxn:
warm and humidify air
lighten skullenhance
resonance of voice
sinus infections
Fontanelsaka soft spotallows for movement through birth canal
close up by 2 years of age
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
Thoracic VertebraeLarger than cervical
Articulate with ribs
12 vertebrae
Lumbar Vertebraebiggest vertebrae
bears most of body’s weight
small of back5 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 directly
next 2 (3) pairs are FLOATING RIBS- no cartilaginous attachment to sternum
Ribs
usu break at greatest curvature
middle ribs commonly fractured
Sternumaka breastbone~ 6” longxyphoid process doesn’t completely ossify until about 40 years old
Hyoid BoneOnly bone in body that doesn’t articulate w/ other bones
Enables us to talk
Smallest bones of body
Spongy & Compact bone
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
growth takes place at the epiphyseal plates on the long bones
most bones of body form this waymore complex methodby age 25 all bones are ossifiedclavicle- last bone to stop growing
bone REMODELING occurs continuously thru-out life
Male vs FemaleSkull: mastoid process, size of skull, forehead, weight
Limbs
Pelvic cavity: wider in females, pubic arch > 90o
aka articulationbind parts of skeletal systemmake bone growth possibleallow parts of skeleton to change
shape during childbirthenable body to move during muscle
contraction
230 joints in body
Joints
3 classifications:immovableslightly movablefreely movable
Fibrousbasically NO movement
bones lie in close contact w/ each other
ex: sutures in skull
Cartilaginoushyaline cartilage connects bones
slightly movable
Synovial Jointsfreely movablesynovial fluid
reduces frictionjoint capsulemenisci-bursae6 types
Ball and Socketwider range of motion
hipshoulder
Condyloidcondyle fits into elliptical cavity
variety of m’ments in different planes; rotational m’ment not allowed
Gliding Joint (plane)most joints in wrists & ankles
allow sliding & twisting motion
Pivot jointscylindrical bone rotates
rotation around central axis
Hinge jointallows for flexion and extension
Saddle Jointvariety of m’ment
top related