First Plantar Interosseous Muscle

Origin

The first plantar interosseous muscle originates from the medial aspects of the base and body of the third metatarsal bone.

Insertion

The fibers of the first plantar interosseous muscle travel anteriorly to the third toe and insert, via a short tendon, onto the:

- medial aspect of the base of the proximal phalanx of third toe;

- extensor expansion of third toe.

Key Features & Anatomical Relations

The first 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 adductor hallucis muscle and the second lumbrical muscle of foot;

- inferior to the second dorsal interosseous muscle of foot;

- medial to the third metatarsal bone;

- lateral to the second metatarsal bone.

Actions

The first plantar interosseous muscle is involved in multiple actions:

- adducts the proximal phalanx of third toe (i.e., draws it towards the longitudinal axial line of the second toe) at the third metatarsophalangeal joint;

- simultaneously flexes the third metatarsophalangeal joint and extends the interphalangeal joints of the third 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 first plantar interosseous muscle is involved in multiple actions:

- adducts the proximal phalanx of third toe (i.e., draws it towards the longitudinal axial line of the second toe) at the third metatarsophalangeal joint;

- simultaneously flexes the third metatarsophalangeal joint and extends the interphalangeal joints of the third toe (Standring, 2016).