Lumbricals

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Original Author(s): Oliver Jones
Last updated: October 17, 2022
Revisions: 5

Original Author(s): Oliver Jones
Last updated: October 17, 2022
Revisions: 5

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The lumbricals are intrinsic muscles of the hand. There are four lumbricals – each associated with a digit.

  • Attachments: Originates from the tendon of the flexor digitorum profundus. Inserts onto the radial aspect of the extensor hood of each digit.
  • Actions: Flexion at the metacarpophalangeal joint and extension at the interphalangeal (IP) joints.
  • Innervation:
    • Lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve.
    • Medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve.
  • Blood supply: Superficial and deep palmar arches

Figure 1 – The lumbricals of the hand. Note the differing unipennate and bipennate structure.