Lumbricals Manus

Joe Muscolino

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The lumbricals manus intrinsic muscles of the hand. The flexor digitorum profundus and adductor pollicis have been ghosted in.

The Lumbricals Manus muscles are members of the Central Compartment Group of intrinsic muscles of the hand, composed of the:

  • Adductor pollicis
  • Lumbricals manus
  • Palmar interossei
  • Dorsal interossei manus

 

There are four Lumbricals Manus muscles, named #1, #2, #3, and #4, from radial/lateral (thumb side) to ulnar/medial (little finger side).

 

ATTACHMENTS:

  • The lumbricals manus attach from the distal tendons of the flexor digitorum profundus to the distal tendons of the extensor digitorum.
    • The lumbricals manus attach into the tendons going to fingers #2-5 (index, middle, ring, little)
    • Each lumbrical manus attaches into the radial side of its respective finger.
    • The distal tendons of the extensor digitorum form the dorsal digital expansion.

 

ACTIONS:

  • Flexes fingers #2-5 at the metacarpophalangeal joints.
  • Extends fingers #2-5 at the proximal and distal interphalangeal joints.

 

NOTE: Lumbricals manus can also abduct/adduct fingers #2-5. They abduct the index finger, radially abduct the middle finger, and adduct the ring and little fingers.