Wrist and Hand Flashcards
list the carpal bones in the proximal row (M-L)
pisiform, triquetrum, lunate, scaphoid
list the carpal bones in the distal row (M-L)
hamate, capitate, trapezoid, trapezium
how many degrees of freedom are at the humeroulnar articulation?
1
why is there only 1 df at the humeroulnar joint?
so that muscles that originate on the distal humerus have more stability to allow for distal mobility
what is the main weight bearing joint fixed in closed chain of the wrist and hand?
the radiocarpal joint
what type of relationship do the “working end” of levers have?
inverse relationship
the radius expansion at carpus is primarily for?
weight bearing
the ulna expansion at the humerus is primarily for?
site of muscle attachment
the ulna expansion at carpus is modified for radius and hand to rotate creating a space called…
ulnocarpal space with triangular fibrocartilage
what is the central column/pillar effect?
think of a bridge the center is the most stable and keep the bridge standing without it it would fall. In the hand think of the lunate and capitate so CMC 3 is most stable
what drives motion in the hand around central column?
thenar and hypothenar
what two planes does biaxial motion occur in?
frontal and saggital
what plane does flexion and extension of the wrist occur in?
saggital plane about an M-L axis
what is the normal range for wrist flexion?
80-90º
what is the normal range for wrist extension?
70-80º
what plane does radial and ulnar deviation occur in?
frontal plane about an A-P axis
what is the normal range for radial deviation?
20-25º
what is the normal range for ulnar deviation?
30-35º
what is something that is a restricter to radial deviation?
radial styloid
what articulates proximally at the radiocarpal joint?
radius and radioulnar disk/TF
what articulates distally at the radiocarpal joint?
scaphoid, lunate and triquetrum
what carpal bone articulates with the lateral radial facet of the radiocarpal joint?
scaphoid
what carpal bone articulates with the medial radial facet of the radiocarpal joint?
lunate
what carpal bone articulates with the inferior radial facet of the radiocarpal joint?
triquetrum
T/F there is no formal carpal articulation with the ulna
true
the proximal carpal row forms what surface?
a single biconcave surface (scaphoid and lunate together)
what does the biconcave surface do?
alters shape to accommodate forearm and hand position
which proximal bone is not included in the proximal row of carpals?
the pisiform
what is the function of the pisiform?
it is a sesamoid bone, functions to increase MA
T/F muscles act directly on the RC joint
false no muscles act directly on the RC joint
how is motion created at the Rc joint if no muscles act directly on it?
ligamentous forces distributed and muscles that insert at the distal carpals and metacarpals create motion
is flexion or extension greater at the radiocarpal joint?
flexion
is ulnar deviation or radial deviation greater at the radiocarpal joint?
ulnar deviation
what results in ROM contribution differences at the radiocarpal joint?
proximal RC incongruence and angulation
what is the midcarpal joint?
the joints between the distal and proximal row of carpals with no isolated capsule, interrupted multiarticular surface
how many degrees of freedom are at the midcarpal joint?
2
what type of joint is the midcarpal joint?
condyloid
is flexion or extension greater at the midcarpal joint?
extension
is radial deviation or ulnar deviation greater at the midcarpal joint?
radial deviation
what are the intercarpal joints?
articulations between all of the carpal bones
what does the intercarpal joints allow for?
minimal movement to accommodate hand and wrist positioning
the intercapal joints are bound together by many ligaments.. what does this do for the joint?
it means there is little give allotted
which side is more mobile at the intercarpal joints (ulnar or radial) and why?
ulnar side is more mobile bc there is a bigger gap between the ulnar styloid and the carpal bones then the radial styloid and carpal bones
which ligament is stronger? the palmar ligament or the dorsal ligament
palmar ligaments
what is the most common carpal bone dislocated?
the lunate
which way does the lunate dislocate and why?
palmarly bc there is a weakened area palmarly near the lunate making it unstable
the proximal pole of the scaphoid has no ligament attachment dorsally which causes the formation of…
ganglion cyst
describe the dorsal radiocarpal ligament
thickening of capsule
lunate and radius contact
check rein to end range wrist flexion
what is the radial collateral ligament a check rein to?
ulnar deviation
what is the ulnar collateral ligament a check rein to?
radial deviation
describe the volar (palmar) radiocarpal ligament
it is the most important of all ligaments for stability and passive mobility contribution
3 distinct bands all intracapsular
on average 85º of wrist flexion is expected. what does the RC and MC joint contribute?
50% from RC
35% from MC
on average 85º of wrist extension is expected. what does the RC and MC joint contribute?
35% from RC
50% from MC
what are the coupled motions at the wrist?
flexion and ulnar deviation
extension and radial deviation
which styloid process (radial or ulnar) projects more distally?
radial
what is the ulnar tilt angle?
25º (bc the radial styloid process projects further than the ulnar)
at the radiocarpal what is moving on what?
CONVEX carpals moving on a CONCAVE radius
review: if it is concave moving on convex is roll and slide opposite or same direction?
same direction
review: if it is convex moving on concave is roll and slide opposite or same direction?
opposite directions
with wrist flexion at the radiocarpal joints what is the roll and slide?
palmar roll and dorsal slide
with wrist extension at the radiocarpal joints what is the roll and slide?
dorsal roll and palmar slide