Second lumbrical muscle
Musculus lumbricalis secondus
- Related terms: Lumbricals (2)
Definition
Second lumbrical muscle | |||
Origin | From the lateral side of the second flexor digitorum profundus tendon to the third digit (middle finger) | ||
Insertion | Extensor expansions of the 3rd digit (middle finger) | ||
Artery | Superficial palmar arch, deep palmar arch, common palmar digital arteries, dorsal digital artery | ||
Innervation | Median nerve (common palmar digital branch) | ||
Action | Flexes the metacarpophalangeal joint and extends the proximal and distal interphalangeal joints of the middle finger | ||
The second lumbrical muscle is a slender, unipennate intrinsic muscle of the hand. It originates from the radial side (and adjacent volar surface) of the second flexor digitorum profundus (FDP) tendon, which is destined for the middle finger.
The muscle then courses distally, passing around the lateral side of the metacarpophalangeal (MCP) joint of the middle finger. It eventually reaches the dorsal aspect of the hand, where it inserts into the dorsal digital expansion (extensor expansion) covering the middle finger. This unique insertion mechanism enables the second lumbrical to flex the MCP joint of the middle finger while simultaneously extending both the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of that same finger.
References
Valenzuela M, Launico MV, Varacallo MA. Anatomy, Shoulder and Upper Limb, Hand Lumbrical Muscles. [Updated 2023 Nov 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534876/
