Wrist

TERMINOLOGY

• Articulation complex comprising distal radioulnar, radiocarpal, ulnocarpal, pisotriquetral, midcarpal, and carpometacarpal joints

• Distal radius: Lister tubercle on dorsal surface acts as fulcrum for action of extensor pollicis longus
• Distal ulna: Ulnar variance refers to length of ulnar head relative to distal radius: Ulnar negative (25%) or ulnar positive (15%)
• Proximal carpal row: Scaphoid, lunate, triquetrum, pisiform

Scaphoid: Proximal and distal pole separated by waist

– Tuberosity = volar prominence of distal pole

Lunate: 1/2 moon-shaped

Triquetrum: Triangular-shaped

Pisiform: Pea-shaped, sesamoid-type bone to which flexor carpi ulnaris attaches and continues distally as pisohamate and pisometacarpal ligaments
• Distal carpal row: Trapezium, trapezoid, capitate, hamate

Trapezium: Saddle-shaped bone linking carpus and thumb

Trapezoid: Wedge-shaped bone

Capitate: Head (proximal), neck (midportion), and body (bulky distal portion)

Hamate: Hook (hamulus) arises from palmar surface

• Extrinsic (on palmar or volar aspects of wrist) or intrinsic (between carpal bones)
• Major wrist stabilizers: Volar ligaments
• Extrinsic ligaments

Palmar: Radioscaphocapitate, radiolunotriquetral, radioscapholunate, ulnotriquetral, ulnolunate, scaphotriquetral

Dorsal: Scaphotriquetral, radiotriquetral, ulnotriquetral, radial collateral
• Intrinsic ligaments

Proximal interosseous: Scapholunate, lunotriquetral

Distal interosseous: Trapeziotrapezoid, trapeziocapitate, capitohamate

• Flexors, deep

Flexor digitorum profundus: Ulnar shaft → index, middle, ring, and little finger distal phalangeal bases

Flexor pollicis longus: Radial shaft, interosseous membrane, and coronoid process ulna → distal phalangeal base thumb
• Flexors, superficial

Flexor carpi radialis: Medial epicondyle → 2nd metacarpal base

Palmaris longus: Medial epicondyle → palmar aponeurosis

Flexor carpi ulnaris: Medial epicondyle and proximal ulna → pisiform

Flexor digitorum superficialis: Medial epicondyle, coronoid process ulna, and radius shaft → middle phalangeal bases of digits 2-5
• Extensors, deep

Abductor pollicis longus: Midulna → radial aspect 1st metacarpal base

Extensor pollicis brevis: Midradius → proximal phalangeal base of thumb

Extensor pollicis longus: Midulna → distal phalangeal base of thumb

Extensor indicis: Midulna → ulnar side extensor digitorum tendon → 2nd digit extensor hood
• Extensors, superficial

Extensor carpi radialis longus: Lateral supracondylar ridge humerus → 2nd metacarpal base

Extensor carpi radialis brevis: Lateral humeral epicondyle → 3rd metacarpal base

Extensor digitorum: Lateral humeral epicondyle → distal phalangeal bases digits of 2-5

Extensor digiti minimi: Lateral humeral epicondyle → extensor hood of little finger

Extensor carpi ulnaris: Lateral humeral epicondyle → 5th metacarpal base

• Flexor retinaculum

Also called transverse carpal ligament: Attached to pisiform and hook of hamate, scaphoid, and trapezium
• Extensor retinaculum

Attaches to ulnar styloid process, triquetrum, and pisiform medially; crosses obliquely to attach to Lister tubercle and radial styloid process laterally

– Sends septa to radius, creating 6 separate compartments for extensor tendons

Compartment contents

– 1st: Abductor pollicis longus and extensor pollicis brevis

– 2nd: Extensor carpi radialis longus and brevis

– 3rd: Extensor pollicis longus

– 4th: Extensor digitorum and extensor indicis

– 5th: Extensor digiti minimi

– 6th: Extensor carpi ulnaris

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Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off