Skeletal System - General Flashcards
(31 cards)
functions of the skeleton
support/protection, framework for the body, protects organs; lever for muscles, with muscles as force; hematopoiesis, tissues in some bones (sternum, ilium) produce blood cells; storage for minerals, 90% of Ca and Phosphate reserves are stored in bones
osteoblast
bone forming cell
osteoclast
cells that break down/remodel/reshape bone
osteocyte
mature bone cell
compact bone
densely packed bone on external surface (shell/collar)
spongy/cancellous bone
loosely organized bone found in the interior, esp at ends
medullary cavity
cavity located in the interior of long bones
diaphysis
shaft/body of a long bone
epyphysis
end of a long bone, location of spongy bone
articular cartilage
hyaline cartilage located on articular ends of bone
periosteum
connective tissue layer on outer surface of bone
endochondral ossification
bone formation:
- most of system starts as hyaline model
- 12th week of dev, osteoblasts start to lay down compact collar on outside of cartilage
- invade into diaphysis and start to change to spongy bone (PRIMARY OSSIFICATION CENTRE)
- inner to spongy and compact deposits on outer surface continue
- osteoclasts from periosteum invade diaphysis, begin to break down spongy bone forming the medullary cavity
- @ birth, -blasts invade cartilage at epiphysis and convert to spongy bone (SECONDARY OSSIFICATION CENTRE)
- between these centres is a growing zone of epiphyseal cartilage
- medullary cavity expands to ephyseal ends and blood-forming cells invade cavity
- epiphyseal cartilage continues to form at end of long bones while -blasts convert cartilage to bone in ends faster than new cartilage forms
- all cartilage in primary and secondary centres is converted to bone and bone stops growing (late teens, 20s)
epiphyseal line
location where ossificaiton centres join
intramembranous bone formation
skull bones, clavicle, mandible, maxilla are formed from mesenchyme rather than cartilage model - gradual invasion of -blasts and -cytes to form bone
articulations (3 types)
classified according to tissue type that joins the bones; fibrous, cartilaginous, synovial
fibrous articulations
gomphosis (btwn root of tooth and bone of maxilla/mandible); suture (fibrous membrane btwn bones of skull to allow growth eventually ossify); syndesmosis (bones joined by fibrous bands of connective tissue i.e. interosseus membrane btwn radius and ulna and distal end of tib/fib)
cartilagenous articulations
synchondrosis (bones joined by hyaline cartilage i.e. epiphyseal cartilage btwn ossification centres - impermanent, or at anterior end of rib); symphysis (bones joined at fibrocartilage pad - intervertebral disc and btwn pubic bones)
synovial articulations
surrounded by joint capsule; capsule is thickened to form intrinsic ligaments (may also have extrinsic ligaments that join bone but are not part of the capsule); articular ends covered in hyaline; inner lining of synovial membrane that secretes synovial fluid to lubricate + absorb shock + nourish cartilage; may have menisci (pads) or labrum (rings) to deepen joint/provide shock absorption; outside may have synovial pads (bursa) to protect soft tissue + reduce friction (most often freely movable joints)
flexion
decrease in joint angle; mvt in saggital plane
extension
increase in joint angle; mvt in saggital plane
ABduction
mvt of bone away from midline; middle finger is midline of hand, 2nd toe is midline of foot
ADduction
mvt of bone toward midline; middle finger is midline of hand, 2nd toe is midline of foot
pronation
medial rotation of limb; rolling radius over ulna
supination
lateral rotation of limb; from pronation, rolling radius back to anatomical position
