Chapter 7 - wrist

actions at the wrsit

flexion/extension, radial/ulnar deviation

joints of the wrist

radiocarpal and midcarpal joints

the midcarpal joint separates

distal and proximal rows of carpal bones

the wrist joints both

move the same amount with wrist motion

because of TFCC, there is no

ulnar articulation with he carpal bones

carpal bones

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

capitate bone is

the base of where all things happen

hook of hamate is an

attachment for the carpal tunnel

pisiform is designed for

soft tissue mobilization

high fracture risk at wrist

radius and scaphoid

lissauer's tubercle indicates

the dorsal surface of the wrist (on the radius)

the distal radius is

biconcave

ulnar tilt

radial side is more distal than the ulnar side at about 25 degrees

because of ulnar tilt, we are permitted more

ulnar deviation at the wrist

radial deviation is limited by

the radial styloid process

palmar tilt

the palmar side of the radius is more proximal by about 10 degrees

palmar tilt permits

more flexion of the wrist

proximal row of carpal bones

scaphoid, lunate, triquetrum, pisiform

the proximal row of carpal bones are

relatively unstable with a small amount of muscular and ligament support

the scaphoid is primarily covered in

articular cartilage due to large amount of articulations - radius, capitate, trapezium, trapezoid, lunate

the scaphoid is freqeuntly under stress, making it

frequently fractured

scaphoid is not well

vascularized, doesnt heal well

lunate is considered the most

unstable of carpal bones, held in place almost exclusively by scapholunate ligament

the scaphoid and lunate articulate on the capitate as

concave articulations on convex capitate

normal ulnar variance

0mm, radius and ulna should line up

with proximal migration of the radius, especially with a radial head re-section

carpals get pulled into the ulna and compress the TFCC

the TFCC is

85% avascular and does not heal well

radial shortening can

increase stress on distal radioulnar joint, TFCC and wrist

pisiform is embedded in

tendon of flexor carpi ulnaris

pisiform and hook of hamate serve as attachment points for

transverse carpal ligament

distal row of carpal bones

trapezium, trapezoid, capitate, hamate

trapezium articulates with

MC 1

trapezoid articulates with

MC 2

capitate articulates with

MC 2, 3, 4

hamate articulates with

MC 4-5

capitate

axis of rotation for wrist motion, central pillar of hand for longitudinal stability

transverse carpal ligament

prevents flexor tendons from bowstringing with activation

ulnar attachment for transverse carpal ligament

hook of hamate and pisiform

radial attachment for transverse carpal ligament

tubercle of trapzeium and scaphoid tubercle

what runs under the transverse carpal ligament, in the carpal tunnel

flexor tendons and median nerve

contact area of radiocarpal joint is maximized in

a little extension with a little ulnar deviation

wrist ligaments act to

provide stabilization to joints and provide feedback for proprioception

dorsal radiocarpal ligament is taut with

flexion and pulls carpals radially away from ulna

palmar collateral ligament is taut with

extension and pulls carpals away from ulna

radial collateral ligament is taut with

ulnar deviation

ulnar collateral ligament is taut with

radial deviation

the articular disc is

biconcave at triquetrum and distal ulna

AOR for midcarpal and radiocarpal joints is

through the convex capitate

flexion/extension AOR for wrist

M-L axis in sagittal plane

ulnar/radial deviation AOR for wrist

A-P axis in frontal plane

why is the wrist not three degrees of freedom

shape of proximal carpals and distal radius limited rotation at the wrist

the wrist allows for more sagittal motions of

flexion (70-85%) than extension (60-75%)

the wrist allows for more frontal motions of

ulnar deviation (40%) than radial deviation (20%)

capitate movement facilitates

hand movement

with flexion at the radiocarpal and midcarpal joints

palmar roll, dorsal slide

with extension at the radiocarpal and midcarpal joints

dorsal roll, palmar slide

taut with wrist flexion

dorsal joint capsule

taut with wrist extension

palmar joint capsule

with ulnar deviation at the radiocarpal and midcarpal joints

roll ulnarly and slide radially (limited by radial collateral ligaments)

with radial deviation at the radiocarpal and midcarpal joints

roll radially and slide ulnarly (limited by styloid process)

scapholunate ligament is ALWAYS

taut