Quick Facts
Origin: Medial aspects of base and body of fifth metatarsal bone.
Insertion: Medial aspect of base of proximal phalanx of little toe and extensor expansion of little toe.
Action: Adducts little toe at its metatarsophalangeal joint; simultaneously flexes metatarsophalangeal joint and extends interphalangeal joints of little toe.
Innervation: Superficial branch of lateral plantar nerve (S2-S3).
Arterial Supply: Deep plantar arch, lateral plantar, plantar metatarsal, and dorsal digital arteries.
Related parts of the anatomy
Origin
The third plantar interosseous muscle originates from the medial aspects of the base and body of the fifth metatarsal bone.
Insertion
The fibers of the third plantar interosseous muscle travel anteriorly to the little toe and insert, via a short tendon, onto the:
- medial aspect of the base of the proximal phalanx of little toe;
- extensor expansion of little toe.
Key Features & Anatomical Relations
The third plantar interosseous muscle is located in the fourth layer of muscles that are found in the plantar part of the foot. It is a short, unipennate skeletal muscle.
It is located:
- superior to the fourth lumbrical muscle of foot;
- inferior to the fourth dorsal interosseous muscle of foot;
- medial to the fifth metatarsal bone;
- lateral to the fourth metatarsal bone.
Actions
The third plantar interosseous muscle is involved in multiple actions:
- adducts the proximal phalanx of little toe (i.e., draws it towards the longitudinal axial line of the second toe) at the fifth metatarsophalangeal joint;
- simultaneously flexes the fifth metatarsophalangeal joint and extends the interphalangeal joints of the little toe (Standring, 2016).
List of Clinical Correlates
- Clawing of the toes
- Charcot-Marie-Tooth disease
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
Actions
The third plantar interosseous muscle is involved in multiple actions:
- adducts the proximal phalanx of little toe (i.e., draws it towards the longitudinal axial line of the second toe) at the fifth metatarsophalangeal joint;
- simultaneously flexes the fifth metatarsophalangeal joint and extends the interphalangeal joints of the little toe (Standring, 2016).
