Hand and Wrist anatomy

Question 1

joints of the wrist

Answer 1

radiocarpal

ulno-menisco-triquetral

midcarpal

intercarpal

carpometacarpal

distal radio-ulnar

Question 2

TFCC

Answer 2

triangular fibrocartilage complex

provides intrinsic jt stability

consists of several closel related structures- articular disk, UCL, ECU, meniscus, and radioulnar ligaments

Question 3

Dorsal compartment of the hand

Answer 3

1. APL and EPB
2. ECRL and brevis
3. EPL
4. Ext digitorum and indicis
5. Ext digiti minimi
6. Ext carpi ulnaris

Question 4

Carpal tunnel

Answer 4

10 structures-

8 tendons of FDS and FDP (long and ring finger are superficial)

flexor pollicis longus

median nerve

FCR not considered part of the carpal tunnel

Question 5

Retinacular ligaments

Answer 5

transverse retinacular ligaments attach from the flexor sheath to the lateral bands= stabilization

oblique retinacular ligaments

Question 6

Swan neck deformity

Answer 6

hyperextension of PIP joint w/ flexion of DIP joint

Question 7

Boutonniere deformity

Answer 7

aquired lesion of the extensor mechanism, in which PIP joint develops a flexion deformity and the DIP joint develops an extension deformity

extensor mechanism affected

Question 8

zones of flexor tendon injury

Answer 8

zones to locate injury:

zone 1- distal to insertion of FDS

zone 2- distal palmar crease (no man’s land)

zone 3- distal to the distal edge of the transverse carpal ligament

zone 4- carpal tunnel

zone 5- distal portion of the forearm

Question 9

Wrist extension mechanics

Answer 9

prox and dist row move together relative to the radius according to the convex on concave artrokinematic principle

convex lunate rolls dorsally on the radius and simultaneously slides anteriorly (convex on concave)

46% ext occurs in midcarpal jt, rest in radiocarpal jt

Question 10

Carpal bones

Answer 10

lateral to medial, prox to distal:

scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate

Question 11

Carpal ligaments

Answer 11

most are intracapsular:

intrinsic lig- begin and end on carpal bones

extrinsic lig- connect the radius and ulna to the carpus

volar lig are considered the strongest and most important

Question 12

Instrinsic ligaments

Answer 12

connect adjacent carpals to carpals

larger insertion into cartilage than into bone

less elastic fibers than extrinsic

more prone to avulsion failures

Question 13

Extrinsic ligaments

Answer 13

connect radius and ulna to the carals and carpals to the metacarpals

stiffer but lower yield strength

more prone to rupture

Question 14

kinematics

Answer 14

generally, the distal row is considered a single unit; however the proximal row has a lot of intercarpal movement

the prox and distal row move together relative to the radius according to the convex on concave arthrokinematic principle

36% of flexion occurs in midcarpal joint, remaining in radiocarpal

Question 15

Biomechanics of the wrist-FLX and EXT

Answer 15

primary axis through the capitate

closed packed- full EXT position where ligaments are most taut and position most fractures and dislocations occur

Question 16

Radial and Ulnar deviation biomechanics

Answer 16

radial deviation- dist row moves radially with the hand, whereas the prox row moves ulnarly and flexes

ulnar deviation- prox row moves radially and extends

Question 17

Biomechanics of the wrist- radial/ulnar deviation

Answer 17

capitate as axis

UD > RD

in radial deviation, the prox row moves into pronation, flex, and ulnar glide ; distal row moves into supination, ext, and radial glide/

Opposite in ulnar deviation