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Wrist and Hand
The joints of the hand are organized into 3 sets of…
Wrist and Hand
- The joints of the hand are organized into 3 sets of articulations: CMC, MCP and IP.
- The more peripheral CMC joints of the hand are particularly important because they allow the thumb to approach the tips of the other digits and they raise the ulnar border of the hand.
- There is functional interaction and synergy between the extrinsic and intrinsic muscles of the hand. For example, contraction of the ED hyperextends the MCP joints, causing the proximal and distal IP joints to collapse into flexion. However, a coordinated interplay among the ED and intrinsic muscles allow extension of all three joints
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Structures providing stability (e.g. TFCC, ligaments, muscles etc)
Triangular Fibrocartilage Complex
- Ulnar collateral ligament
- Palmer ulnocarpal ligament
- Palmer radio-ulnar joint ligament (covering articular disc)
- Articular disc
- A triangular, fibrocartilaginous disc attaches to the distal end of the radius and the styloid process of the ulna while the apex of the disc attaches to the triquetrum.
Functions
- Primary stabilizer of the distal radio-ulnar joint
- Reinforces the ulnar side of the wrist
- Helps transfer part of the compression forces that cross the hand to the forearm
Pronator Quadratus at the Distal Radioulnar joint
- Effective pronation torque producer
- Stabilizer of the distal radio-ulnar joint
Scapholunate ligament
- Injury to this ligament will result in the lunate extending or facing dorsally
- Extensor carpi radialis longus, extensor carpi radialis brevis, flexor carpi ulnaris, and abductor pollicis brevis tend to supinate the scaphoid, stabilize the SL joint, and therefore protect the SL ligament
Lunotriquetral ligament
- Injury to this ligament results in the lunate flexing or facing volarly (towards the palm)
- Extensor carpi ulnaris pronates and extends the triquetrum, improving LT joint stability
Neuroanatomy
Radial Nerve
- C5-T1
- A direct continuation of the posterior cord of the
brachial plexus
- Innervates the extrinsic extensor muscles of the digits
- Extensor digitorum
- Extensor digiti minimi
- Extensor indicis
- Extensor pollicis longus
- Extensor pollicis brevis
- Abductor pollicis longus
- Supplies sensation to the dorsal wrist/hand and
capsule of thumb CMC joint
- The area of isolated supply is over the dorsal surface of the first web space
Median Nerve
- C6-T1
- Innervates the extrinsic flexor muscles of the
digits
- Flexor digitorum superficialis
- Lateral half of flexor digitorum profundus and flexor pollicis longus (by anterior interosseous nerve)
- Supplies sensation to palmar aspect of lateral 3.5 digits, and capsule of thumb CMC joint
- The area of isolated supply is over the tip of index and/or middle finger
Ulnar nerve
- C8-T1
- Direct branch of medial cord of brachial
plexus
- Innervates medial half of flexor digitorum
profundus
- Deep motor branch supplies the hypothenar muscles, medial two lumbricals, palmar and dorsal interossei, and adductor pollicis
- Supplies sensation to skin over ulnar border
of the hand, and ulnar 1.5 digits
- The area of isolated supply is over the tip of
little finger
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