Four Muscle Layers of the Sole

Mnemonic

Four layers, counted from the skin down. “One, two, three, four: Abductors, Quadratus, Flexors, Interossei”:

• Layer 1 - abductor hallucis, flexor digitorum brevis, abductor digiti minimi
• Layer 2 - quadratus plantae and the lumbricals, with the long flexor tendons
• Layer 3 - flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
• Layer 4 - the interossei, with the tendons of fibularis longus and tibialis posterior

Nerve supply follows the same logic as the hand: the medial plantar nerve is the median nerve of the foot, supplying the equivalent of LOAF, and the lateral plantar nerve is the ulnar, supplying everything else.

Expansion

• Layer 1 - abductor hallucis, flexor digitorum brevis, abductor digiti minimi
• Layer 2 - quadratus plantae and the lumbricals (with the long flexor tendons passing through)
• Layer 3 - flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
• Layer 4 - the plantar and dorsal interossei (with tibialis posterior and fibularis longus tendons)