How do the phalanges work?

Updated: Jan 18, 2018
  • Author: Jay E Bowen, DO; Chief Editor: Craig C Young, MD  more...
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Answer

The phalanges do not contain muscle bellies, and motor function is accomplished only by the flexor and extensor tendons. An overview of the muscles and tendons of the hand is necessary. The thenar muscles consist of 3 intrinsic muscles including the abductor pollicis brevis (which abducts the thumb), the flexor pollicis brevis (which flexes the proximal phalanx of the thumb), and the opponens pollicis (which produces opposition of the thumb).

All 3 intrinsic thenar muscles are supplied by the recurrent branch of the median nerve. The adductor pollicis adducts the thumb and is supplied by the deep branch of the ulnar nerve. The hypothenar muscles are also supplied by the deep branch of the ulnar nerve.

The abductor digiti minimi abducts the fifth digit and flexes its proximal phalanx. The flexor digiti minimi is deeper and also flexes the proximal phalanx of the fifth digit. The opponens digiti minimi, as its name implies, opposes the fifth digit.


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