The plantar interossei muscles of the foot are a group of intrinsic muscles within the fourth layer of the plantar muscles of the foot.
The intrinsic muscles of the foot consist of one intrinsic muscle on the dorsal aspect of the foot (the extensor digitorum brevis), and 4 layers of muscles on the plantar aspect of the foot:
- 1st layer: abductor hallucis, flexor digitorum brevis, abductor digiti minimi
- 2nd layer: quadratus plantae, lumbricals
- 3rd layer: flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
- 4th layer: dorsal interosseri, plantar interossei
Origin
- Medial sides of metatarsals of toes 3 to 5
Insertion
- Extensor expansions on the medial bases of proximal phalanges of toes 3 to 5
Action
- Adduction of toes 3 to 5 at metatarsophalangeal joints
- Resist extension of the metatarsophalangeal joints
- Flexion of the interphalangeal joints
Innervation
- Lateral plantar nerve from tibial nerve: S2, S3
Blood Supply
- Plantar metatarsal artery