MRCS Review – Anatomy Q6

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M edial lumbricals
A dductor pollicis
F lexor digitorum profundus/Flexor digiti minimi
I nterossei
A bductor digiti minimi and opponens

Innervates all intrinsic muscles of the hand (EXCEPT 2: thenar muscles & first two lumbricals – supplied by median nerve)

Pronator teres is innervated by the median nerve. Palmaris brevis is innervated by the ulnar nerve

Ulnar nerve

Origin

  • C8, T1

Supplies (no muscles in the upper arm)

  • Flexor carpi ulnaris
  • Flexor digitorum profundus
  • Flexor digiti minimi
  • Abductor digiti minimi
  • Opponens digiti minimi
  • Adductor pollicis
  • Interossei muscle
  • Third and fourth lumbricals
  • Palmaris brevis

Path

  • Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially over the flexor retinaculum into the palm of the hand.

Image sourced from Wikipedia


Branches

BranchSupplies
Muscular branchFlexor carpi ulnaris
Medial half of the flexor digitorum profundus
Palmar cutaneous branch (Arises near the middle of the forearm)Skin on the medial part of the palm
Dorsal cutaneous branchDorsal surface of the medial part of the hand
Superficial branchCutaneous fibres to the anterior surfaces of the medial one and one-half digits
Deep branchHypothenar muscles
All the interosseous muscles
Third and fourth lumbricals
Adductor pollicis
Medial head of the flexor pollicis brevis

Effects of injury

Damage at the wrist
  • Wasting and paralysis of intrinsic hand muscles (claw hand)
  • Wasting and paralysis of hypothenar muscles
  • Loss of sensation medial 1 and half fingers
Damage at the elbow
  • Radial deviation of the wrist
  • Clawing less in 4th and 5th digits
 

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