Quick Facts
Origin: Tendons of flexor digitorum longus that travel to the fourth and little toes.
Insertion: Medial aspect of extensor expansion of little toe.
Action: Simultaneously flexes metatarsophalangeal joint and extends interphalangeal joints of little toe.
Innervation: Deep branch of lateral plantar nerve (S2-S3).
Arterial Supply: Lateral plantar artery, deep plantar arch, and plantar metatarsal arteries.
Related parts of the anatomy
Origin
The fourth lumbrical muscle of foot consists of two heads:
- the medial head, which originates from the lateral aspect of the tendon of flexor digitorum longus that travels to the fourth toe;
- the lateral head, which originates from the medial aspect of the tendon of flexor digitorum longus that travels to the little toe.
Insertion
The fibers of the fourth lumbrical muscle of foot travel anteriorly to the little toe and insert, via a short tendon, onto the medial aspect of the extensor expansion of little toe.
Key Features & Anatomical Relations
The fourth lumbrical muscle of foot is located in the second layer of muscles that are found in the plantar part of the foot. It is a short, wormlike, bipennate skeletal muscle.
It is located:
- superficial (inferior) to the flexor digiti minimi muscle of foot and the third plantar interosseous muscle of foot;
- deep (superior) to the plantar aponeurosis;
- medial to the tendon of flexor digitorum longus that travels to the little toe;
- lateral to the tendon of flexor digitorum longus that travels to the fourth toe and the flexor digiti minimi muscle of foot.
Actions
The fourth lumbrical muscle of foot simultaneously flexes the fifth metatarsophalangeal joint and extends the interphalangeal joints of the little toe (Moore, Dalley and Agur, 2009).
List of Clinical Correlates
- Clawing of the toes
- Charcot-Marie-Tooth disease
References
Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2009) Clinically Oriented Anatomy. Lippincott Williams & Wilkins.
