Plantar Interossei Beneath the Skin, Plantar View

Description

Seen from the plantar aspect beneath the skin, the central and lateral compartments of the sole are opened to reveal the plantar interossei occupying the intermetatarsal spaces. Each muscle belly lies on the medial or lateral surface of metatarsals III to V, running distally to slender tendons that pass deep to the metatarsophalangeal joints and blend with the plantar plates and extensor expansions on the proximal phalanges. The metatarsal shafts form the osseous backdrop, with the hallux phalanges medial and the lesser toe phalanges aligned distally, clarifying how these short muscles sit deep to the long flexor tendons in the forefoot. Bone and muscle relationships read cleanly. Functionally, the plantar interossei adduct digits III to V toward the axial line of the second toe and assist the lumbricals with metatarsophalangeal flexion while permitting interphalangeal extension, a combination that stabilizes the toes during late stance and push-off. Loss of intrinsic muscle strength, common in diabetic neuropathy or following lateral plantar nerve injury (for example after tarsal tunnel decompression or calcaneal fracture), shifts balance toward the extrinsic toe extensors and flexors, contributing to claw toe deformity, transfer metatarsalgia, and focal plantar keratoses beneath the metatarsal heads. The interossei also become relevant in forefoot compartment syndromes and in surgical dissection planes for intermetatarsal approaches where the deep transverse metatarsal ligament and plantar plates must be respected. Use this plantar view in gross anatomy and lower-limb dissection teaching to separate intrinsic from extrinsic toe mechanics, and in podiatry or orthopaedic publications discussing metatarsophalangeal instability, toe deformities, and plantar forefoot pain patterns. It also supports clinical education for nerve lesions of the lateral plantar nerve and rehabilitation goals after midfoot and forefoot surgery. Anatomical accuracy verified by SciePro's Medical Advisory Board.