Wrist Flashcards
how many degrees of freedom in the wrist and how many AOR?
2 DOF and biaxial
where are the wrist AOR
radiocarpal (proximal) and midcarpal (distal)
where does the 1st MC articulate?
the trapezium
what is the most commonly fracture carpal?
scaphoid (60-70%)
which carpal is the most frequently dislocated
lunate
what is the largest metacarpal
capitate
why is the capitate important (2)
- creates a rigid column for the hand
- AOR for all wrist movement passes through it
what forms the structure for the carpal tunnel?
proximal carpals
where is the majority of motion in the wrist?
medial mid carpal joint
what are the two major wrist tilts and their degrees
ulnar (25) and palmar (10)
where do the four motions of the wrist pass through?
the capitate bone
describe wrist extension in open chain
convex on concave
- capitate on lunate on radius
describe wrist flexion in open chain
convex on concave
- capitate on lunate on radius
describe the frontal plane arthokinematics at the wrist
convex on concave
- capitate on (scaphoid, lunate, and triquetrum in succession and reversed in the opposite direction)
how do the four wrist motions change in closed chain?
concave on convex
how does RA changes the wrist position?
chronic inflammation > bone and ligament deformity > ulnar deviation
all wrist flexors pass under the flexor retinaculum except which muscles? where do they attach?
PL (flex ret and palm apon) and FCU (pisiform)
what are the primary wrist extensors
ECRL/ECRB + ECU
what muscle is implicated in tennis elbow and why
ECRB - a hard squeeze encourages wrist extension which leads to stress on the ECRB
when is grip strength strongest? why?
about 30 deg wrist extension - minimized active/passive insufficiencies of long finger flexors and wrist extenders
what kind of patients require tenodesis grip?
tetraplegic patients with C6 intact
describe tenodesis grip
wrist extension promotes finger flexion via exploiting passive insufficiency of long finger flexors
