Skeletal System
I.
Functions of the skeletal system
A.
Support of soft tissue
B.
Protection of vital organs
C.
Aid in movement, forms system of levers for muscles to pull against
D.
Blood cell formation (hematopoiesis)
E.
Storage of minerals, esp, calcium and phosphate
II.
A.
1.
2.
3.
4.
B.
1.
2.
3.
4.
5.
Bone structure
Classification:
Long bones: Greater in length than width, absorb stress, arms and
legs
Short bones: Equal l and w, cube shaped, wrists and ankles
Flat bones: Thin and flat, cranium, ribs, sternum
Irregular bones: Odd, face and vertebrae
Parts of a long bone
Diaphysis: Shaft
Epiphysis: End, form joints, covered with hyaline cartilage (articular
cart.)
Periosteum: Sheet of c.t. Covers bone except art. Cart.,
a.
Large blood supply--nourishment
b.
Osteoblasts--cell that produce and repair bone
c.
Site of tendon and ligament attachment
Internal
a.
Compact bone: walls of diaphysis
b.
Spongy bone: inside epiphysis, filled w/ red
marrow
c.
Medullary cavity: in diaphysis, filled w/
yellow marrow, lined by membrane called
endosteum
Composition:
a.
Inorganic: calcium phosphate and calcium
carbonate>>hard and brittle
b.
Organic: Collagen>>flexibility and strength
in matrix, cells
(1).
Osteoblasts: young bone cell, on surface
(2).
Osteocytes: mature bone cell , contained
in lacuna
(3).
Osteoclasts: wander through tissue,
dissolve bone
6.
III.
A.
Microscopic structure:
a.
Compact bone: concentric circles of osteons,
osteocytes lie in lacunae, osteoni canals-blood vessels, canaliculi--tiny canals of
cytoplasm, allow cells to communicate
b.
Spongy bone: Thin plates of bone
(trabeculae) with spaces in between filled w/
red marrow, osteocytes
Bone growth and development:
B.
2 ways bone forms:
Intermembranous bone
Endochondral bones
Epiphyseal plate--narrow band of cartilage between epi and diaph.
C.
Growth
IV.
1.
Interstitial--lengthwise, at epiphyseal plate. Controlled by
hormones and growth control factors
a. Epiphyseal line--line of bone replacing cartilage of
epiphyseal plate
2.
Appositional growth--increase width, by osteoblast in
periosteum, Med cavity growing as
destroy bone
Surface features of bone
SITE FOR MUSCLE ATTACHMENTS:
Process -any projection from bone surface
Ex. styloid process of temporal bone
Tuberosity-large rounded projection, rough
Ex. deltoid tubosity of humerus
Crest-narrow ridge of bone, prominent
Ex.crest of tibia
Line-narrow ridge of bone, less prominent
Ex. femur
Tubercle-small rounded projection or process
Ex. Proximal end of the humerus
Epicondyle-rounded area above condyle
Ex. femur, humerus
Spine-narrow or pointed process
Ex. scapula, vertebrae
Projections for joints:
Head-bony expansion on a narrow neck
EX. rib, femur, fibula, humerus
Facet-smooth, flat articular surface
Ex. Thor. vertebrae, ribs
Condyle-Knuckle, large, rouged articulation
Ex.long bones, mandibles skull
Ramus-armlike ball of bone
Ex.mandible
Depressions or openings:
Meatus-canal like passageway
Ex. ext.auditory. meatus
Sinus-cavity within bone, lined by mucous membrane
Ex. frontal sinus others in skull
Fossa
depression or groove
subscapular fossa
Groove
furrow
Fissure
narrow slitlike opening
orbital fissure of sphenoid
foramen
round or oval opening
foramen magnum of skull, vertebral foramen
V.
C
Joints
Junctions between bones
Classified based on material that connects bones and movement
allowed
A.
Fibrous joints
1.
Dense connective tissue
a.
Little or no movement
2.
Examples
a.
Sutures of cranium
b.
fibula
Syndesmoses--bones separated by some distance, distal ends of tibia and
c.
Gomphoses--pegs in sockets, teeth in sockets
B.
Cartilaginous joints
1.
Cartilage
a.
Slightly moveable
2.
Examples
a.
Costal cartilage between ribs and sternum
b.
Fibrocartilage of pubic symphysis and discs
C.
Synovial joints
1.
membrane
Bones bound by articular capsule filled w/ fluid secreted by a synovial
a.
Shock absorbing, lubricating
2.
Types of
a.
Plane (gliding)--art. sur. Flat, ankles and wrists, clavicle and sternum
b.
Hinge--convex fits concave, elbow, knee, back and forth movement
c.
Pivot--cylindrical sur. Rotates within ring, atlas and axis of vertebral
column, rotation
d.
Condyloid--oval shaped condyle fits cavity on other, wrist and radius/ulna,
back and forth and circular
e.
Saddle--convex fits concave, thumb, back and forth, side to side, some
pivotal movement
f.
Ball and socket--hip and shoulder, more movement than any other type
3.
Movements of joints
a.
Flexion
b.
Extension
c.
Abduction
d.
Adduction
e.
Circumduction
f.
Rotation
g.
Pronation
h.
Supination
i.
Eversion
j.
Inversion
k.
Elevation
l.
Home
Depression
Anatomy Notes