Fragment II

In anatomy, the thumb has many names: the first finger, pollex, digitus primus, or digitus I. It consists of three bones:

  • distal phalanx (of the first digit)
  • proximal phalanx (of the first digit)
  • first metacarpal

Eight muscles control its movements:

  • opponens pollicis
  • abductor pollicis brevis
  • flexor pollicis brevis
  • adductor pollicis
  • flexor pollicis longus
  • abductor pollicis longus
  • extensor pollicis brevis
  • extensor pollicis longus

The first four of these muscles are in the hand and the first three of these form the thenar eminence, the fleshy mound on the palm below the thumb. The latter four muscles come from the forearm, where, like marionette strings, nerves direct the muscles.


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