First Plantar Interosseous (Left) (Musculus interosseus plantaris primus)
Educational content only — not medical advice.
Anatomy
The first of the three bipennate plantar interossei, lying between the third and fourth metatarsals. Each plantar interosseous arises from the base and medial side of one metatarsal and inserts on the medial base of the corresponding proximal phalanx, joining the extensor hood. They are the adductors of the toes (PAD) toward a line through the second toe.
Origin & insertion
From the base and medial side of the third metatarsal, to the medial base of the proximal phalanx of the third toe with the extensor hood.
Action
Adducts the third toe toward the second and flexes its metatarsophalangeal joint.
Innervation
Lateral plantar nerve (S2–S3).
Clinical notes
The plantar interossei are the first to waste in intrinsic-foot atrophy; hollowing of the intermetatarsal spaces on inspection, and their denervation on electromyography, localise a deep-branch lateral plantar lesion.
Related structures
Educational references
FAQ
What is the role of the First Plantar Interosseous (Left)?
The first of the three bipennate plantar interossei, lying between the third and fourth metatarsals. Each plantar interosseous arises from the base and medial side of one metatarsal and inserts on the medial base of the corresponding proximal phalanx, joining the extensor hood. They are the adductors of the toes (PAD) toward a line through the second toe.
Why is the First Plantar Interosseous (Left) clinically important?
The plantar interossei are the first to waste in intrinsic-foot atrophy; hollowing of the intermetatarsal spaces on inspection, and their denervation on electromyography, localise a deep-branch lateral plantar lesion.
Source & license
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