Fourth Layer of the Plantar Muscles Plantar and Dorsal Interossei Diagram

The fourth layer of plantar muscles includes the plantar interossei (three, adduct toes 3-5 from metatarsals to proximal phalanges) and dorsal interossei (four, abduct toes 2-4 from adjacent metatarsals). Both are deep to lumbricals, ulnar-innervated, and stabilize the forefoot during push-off by controlling toe alignment.