Chapter 7 - The wrist Flashcards
Order of carpal bones(dorsal view)
trapezium trapezoid capitate hamate
scaphoid lunate triquetrum
ulnar tilt
radius tilt at distal radioulnar joint = 25 degrees
palmar tilt
anterior and posterior tilt of 10 degrees at distal radioulnar joint
transverse carpal ligament
- attaches to trapezium and scaphoid tubercle
- also hamate and pisiform
medial compartment of wrist
triquetrum and lunate
midcarpal joint
proximal = triquetrum, lunate, scaphoid distal = hamate, capitate
convex = hamate, capitate, trapezoid concave = triquetrum, lunate, scaphoid
lateral compartment of wrist
trapezium and trapezoid
ligament preventing medial slide
dorsal radiocarpal ligament
triangular fibrocartilage complex
1) ulnar collateral ligament
2) palmar ulnocarpal ligament
3) articular disc
osteokinematics of wrist joint
2 degrees of freedom
- flexion/extension
- ulnar/radial deviation
- slight rotation but not enough
- circumduction = a combination of above
- axis = through capitate
ROM of wrist
- flexion = 0 - 85 degrees
- extension = 0 - 75 degrees
- flexion > extension by 10-15 degrees
- based on palmar tilt of radius
- ulnar deviation = 0-40 degrees
- ulnar tilt of radius
- radial deviation = 0-20 degrees
- ulnar deviation usually x2 radial deviation
ROM necessary for functional ADL’s
- flexion = 40 degrees
- extension = 40 degrees
- radial deviation = 10 degrees
- ulnar deviation = 30 degrees
advantage of wrist being a double-joint system
allows less movement per joint which makes for more stable joints
- less susceptible to injury
wrist close-packed position
full extension
- extension elongates palm radiocarpal ligaments
- extension used in weightbearing activities of UE(crawling, catching self from fall)
radial deviation
carpus impinges against radial styloid process
- higher percentage of movement occurs at midcarpal joint than radiocarpal joint
- proximal row of carpals flexes slightly(rocking movement)
ulnar deviation
proximal row of carpals extends slightly(rocking movement)
wrist extension
convex-on-concave
- capitate = rolls posterior, slide anterior
- lunate slide
wrist flexion
convex-on-concave
- capitate = roll anterior, slide posterior
- lunate = slide posterior
ulnar deviation
capitate = roll medially, slide lateral
triquetrum, lunate, scaphoid = roll medially
radial deviation
capitate = roll laterally, slide medially
triquetrum, lunate, scaphoid = roll laterally
rotational collapse of the wrist
wrist is made up of a mobile proximal row wedged between two rigid structures: forearm and distal row of carpal bones
- lunate is most frequently dislocated(dependent on ligaments for stability)
- scaphoid most often fractured
ulnar translocation of the carpus
- distal radius is angled 25 degrees in ulnar tilt
- natural tendency for carpus to slide in ulnar direction
- wrist pathology may make wrist yield to these forces resulting in deformity and altered mechanics
primary wrist extensors
extensor carpi radialis longus = base of 2nd MC
extensor carpi radialis brevis = base of 3rd MC
extensor carpi ulnaris = base of 5th MC
secondary wrist extensors
extensor digitorum
extensor indicis
extensor digiti minimi
extensor pollicis longus
extensor retinaculum
- prevents “bowstringing” of tendons
- helps stabilize dorsal side of wrist joint
maximal grip
occurs at 30 degrees extension
- optimal length/tension relationship of wrist flexor muscles
Tennis elbow
lateral epicondylitis –> lateral epicondylagia(no inflammation)
- degeneration of the common extensor tendon
- usually from repetitive activities(commonly occupational)
- extensor muscles of the wrist
Treatment = tylenol, rest, eccentric exercises(causes irritation to cause inflammation to heal)
primary wrist flexors
flexor carpi radialis
flexor carpi ulnaris
palmaris longus(present in 10%)
secondary wrist flexors
flexor digitorum profundus
flexor digitorum superficialis
flexor pollicis longus
palmar carpal ligament
same as extensor retinaculum
- proximal to transverse carpal ligament
- stabilizes tendons
- prevents bowstringing of tendons
flexors vs extensors
flexors produce the most torque because larger cross sectional area
- wrist flexors creat about 70% more isometric torque than extensors
ulnar deviation muscles
extensor carpi ulnaris
flexor carpi ulnaris
paralysis of wrist extensors
- common after CVA
- need external support to keep wrist in neutral position
