Question | Answer |
bones of the skeleton have 2 main groups | axial and appendicular |
axial skeleton | skull, spine and ribcage |
appendicular skeleton | arms and legs |
4 bone shapes | long, short, flat and irregular |
long bones | longer than they are wide (humerus) |
short bones | cube shaped (ankle and wrist) and sesamoid bones within tendons (patella) |
flat bones | thin, flat and slightly rounded (skull) |
irregular bones | complicated shapes (vertebrae) |
bone markings | structural features that play a role in bone function: projections, depression and openings |
projections for muscle and ligament attachment | tuberosity, crest, trochanter, line, tubercle, epicondyle, spine, process |
tuberosity | rounded projection |
crest | narrow, prominent ridge |
trochanter | large, blunt, irregular surface (head of femur) |
line | narrow ridge of bone |
tubercle | small, rounded projection |
epicondyle | raised area above a condyle |
spine | sharp, slender projection |
process | any bony prominence |
4 projections that help form joints | head, facet, condyle, and ramus |
head | bony expansion carried on a narrow neck |
facet | smooth, nearly flat articular surface |
condyle | rounded articular projection |
ramus | arm-like bar |
depressions and openings | meatus, sinus, fossa, groove, fissure, and foramen |
meatus | canal-like passageway |
sinus | cavity within a bone |
fossa | shallow, basin-like depression |
groove | furrow |
fissure | narrow, slit-like opening |
poramen | round or oval opening through a bone |
bone structure | bones have layers that differ for long, short, flat and irregular bones |
bone textures | compact and spongy |
compact bone | dense outer layer |
spongy bone | honeycomb of trabeculae |
structure of long bone | diaphysis, epiphyses, periosteum, endosteum |
diaphysis | shaft of long bone; compact bone collar that surrounds medullary cavity; contains yellow marrow |
epiphyses | expanded ends with a spongy bone interior, epiphyseal line (remnant of growth plate, articular (hyaline)cartilage on joint surfaces |
2 membranes of long bone | periosteum and endosteum |
periosteum | outer fibrous layer, inner osteogenic layer; nerve fibers, nutrient blood vessels, and lymphatic vessels enter the bone via nutrient foramen |
osteogenic layer of periosteum | osteoblasts, osteoclast and osteogenic cells |
endosteum | delicate membrane on internal surfaces of bone; osteoblasts and osteoclasts |
structure of short, flat and irregular bones | periosteum covers compact bone on outside; endosteum covers spongy bone within, spongy bone in flat bones = diploe, bone marrow between trabeculae |
diploe | spongy bone in flat bones |
location of hemopoietic tissue (red bone marrow) | cavities of adults; trabecular cavities of the heads of femur and humurus; trabecular cavities of diploe (spongy bone in flat bones) |
cells of bone | osteoblasts, osetoclasts, osteocytes, osteogenic cells |
osteoblasts | bone forming cells |
osteoclasts | cells that break down (resorb) bone matrix |
osteocytes | mature bone cells |
osteogenic cells | stem cells |
microscopic anatomy of bone | haversian system/osteon: structural unit |
lamella | compact bone; concentric, column-like matrix tubes |
central (haversian) canal | contains blood vessels and nerves |
perforating (Volkmanns) canals | connect central and peripheral canals |
lacunae | small cavities that contain osteocytes |
canaliculi | hairlike canals that connect lacunae |
bone development | osteogenesis/ossification |
osteogenesis/ossification | bone tissue formation; 3 stages: bone formation, postnatal bone growth, bone remodeling and repair |
bone formation | begins in second month of growth |
postnatal bone growth | until early adulthood |
bone remodeling and repair | lifelong |
endochondral ossification | cartilage (endocondral) bone forms by replacing hyaline cartilage; forms most of skeleton (except flat bones); uses hyaline cartilage models; requires breakdown of hyaline cartilage before ossification |
postnatal bone growth | interstitial and appositional |
interstitial growth | postnatal; increases length of bones |
appositional growth | postnatal; increases thickness and remodeling of all bones by osteoblasts and osteoclasts on bone surfaces |
interstitial growth of long bones | epiphyseal plate cartilage organizes into 4 functional zones: proliferation, hypertrophic, calcification, ossification |
proliferation zone | cartilage cells undergo mitosis |
hypertrophic zone | older cartilage cells enlarge |
calcification zone | matrix becomes calcified, cartilage cells die, matrix begins deteriorating |
ossification zone | new bone formation occurs |
classification of bone fractures | position of bone ends, completeness of break, orientation of break along axis, penetration through skin |
position of bone ends after fracture | nondisplaced: ends retain normal position
displaced: ends out of alignment |
completeness of break | complete: broken all the way through
incomplete: not broken all the way through |
orientation of break to the long axis of bone | linear: parallel to long axis
transverse: perpendicular to long axis |
whether or not bone ends penetrate skin | compound (open): ends penetrate
simple (closed): ends do not penetrate |