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Body Surface

The primary surface landmarks of the plantar foot are associated with the calcaneus (tuberosity), and 1st and 5th metatarsal-phalngeal joints. The skin overlying the plantar foot is innervated by the medial calcaneal branches of the tibial nerve, and medial and lateral plantar nerves.

Skeleton and Joints

The bones and joints associated with the plantar foot are the tarsals, metatarsals and phalanges articulating at the joints of the foot. The joints of the foot move in inversion and eversion. The phalanges move in abduction and adduction, and flexion and extension.

Fascial Organization

The thick, fibrous plantar fascia (aponeurosis) overlies the intrinsic muscles of the foot. The plantar fascia, two intermuscular septa and the interosseous fascia subdivide the plantar foot into four compartments ( medial- abductor hallucis and flexor hallucis brevis; central- flexor digitorum brevis, lumbricals, flexor accessorius [quadratus plantae] and adductor hallucis; lateral- abductor digiti minimi and flexor digiti minimi brevis; and interosseous- plantar and dorsal interossei).

Muscles

The medial compartment muscles are active in abduction ( abductor hallucis) and flexion ( flexor hallucis brevis) of the 1st toe. The central compartment muscles are active in flexion ( flexor digitorum brevis) and adduction ( adductor hallucis) of the 1st toe, flexion of toes 2-5 ( flexor accessorius and lumbricals) and extension (interphalangeal) of toes 2-5 (lumbricals). The lateral compartment muscles are active in flexion ( flexor digiti minimi brevis) and abduction ( abductor digiti minimi) of the 5th toe. The interosseous compartment muscles are active in abduction ( dorsal interossei), adduction ( plantar interossei), flexion (dorsal and plantar interossei) and interphalangeal extension (dorsal and plantar interossei) of the toes (2-4).

Innervation

The muscles on the medial aspect of the plantar foot are innervated by the medial plantar nerve, whereas the muscles on the lateral aspect of the plantar foot are innervated by the lateral plantar nerve.

Blood Supply

The terminal branches of the posterior tibial artery, and the medial and lateral plantar arteries supply the plantar foot.