biomechanics of wrist Flashcards
wrist function
controls length tension relationship
fine movements for grip
load transfer from hand to from forearm
hand function
sensory and motor
essential for prehension and fine motor control
thumb opposition
rich supply of sensory receptors
wrist joint type
biaxial
condyloid joint
flexion extension
ulnar radial deviations
2 dof
capsular- equal f and e
normal wrist rom
flex 65-85
ext 60-80
RD 15-21
UD 20-45
functional wrist position
20-35 ext
10-15 UD
close pack wrist
full extension
radiocarpal joint
radius, TFCC, triquetrum, lunate, scaphoid
axial loading sharing- scaphoid/lunate 80%; TFCC 20%
radial styloid typically more distal than ulnar
if ulnar styloid more proximal
- ulnar variance
associated with Keinbocks
if ulnar styloid more distal
+ ulnar variance
associated with TFCC impingment
proximal row of carpal bones
highly mobile
location of most carpal instabilities
susceptible to collapse with load
intrinsic ligaments for proximal row of carpal bones
scapulolunate interosseous
lunotriquetral interosseous
what one muscle attaches to proximal carpal bones
FCU
scaphoid
key participant for wrist action
supports weight of arm (CKC)
transmits forces from hand to forearm
moves with either proximal or distal row of carpals
exerts flexion moment on proximal row
most commonly fractured in FOOSH
lunate
most commonly dislocated carpal bone
exerts extension moment on proximal row
midcarpal joint and distal row of carpals
functional not anatomical joint
distal carpals move as fixed unit
functional union of distal carpals and metacarpals are foundation of transverse and longitudinal arches of the hand
