Intrinsic muscles originate and insert in the foot. Extensor digitorum brevis is the only dorsal intrinsic; the sole is organized in four layers under the plantar fascia.

Superficial plantar trio from the calcaneum: abductor hallucis, flexor digitorum brevis, and abductor digiti minimi—borders and toe flexion for gait stability.

Flexor accessorius straightens the oblique FDL pull; lumbricals act as an anti-buckling mechanism at the toes.

FAF deep flexors and adductors of the hallux and little toe; interossei with PAD adduction and DAB abduction relative to the second toe.

Medial arch is flexible for shock absorption; lateral arch is rigid for weight bearing, with spring ligament and plantar fascia support.

Transverse arch at metatarsal bases; arches held by bone shape, ligaments, and muscle slings—plus pes planus vs pes cavus footprints.

Recap of plantar mnemonics and the three arches maintained by bones, ligaments, and muscles as the basis of gait and clinical foot health.