Innervation of the hand (afferent and efferent):
Afferent (sensory) innervation
Efferent (motor) innervation
All the intrinsic muscles of the hand are innervated by the
Ulnar nerve except for the "LOAF muscles"
Innervation of the foremarm (efferent):
Flexors of the wrist:
All but 2 (flexor carpi ulnaris and a component of flexor digitorum profundus) are innervated by median nerve.
Flexor carpi ulnaris - Innervated by the ulnar nerve
Flexor digitorum profundus - Innervated by both ulnar and median nerves
- Flexion at the DIP joints of index and middle fingers: median nerve (anterior
interosseus nerve which also innervates FPL, damaged during distal humeral
fractures leading to a positive OK sign).
- Flexion at the DIP joints of ring and little fingers: ulnar nerve
Extensors of the wrist (and hand):
All extensors of the wrist are innervated by the radial nerve (posterior interosseous branch).
Median nerve entrapment as it traverses through the carpal tunnely causes carpal tunnely syndrome.
Ulnar nerve injury
- Proximally in the elbow: Weakness, claw hand
- Distally: Claw hand worse symptoms - i.e. ulnar paradox
Mr Kasun Wanigasooriya MBCHB, MRCS
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