Lumbricals (Hand)

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

By TeachMeSeries Ltd (2025)

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