Tibialis Posterior Muscle Anatomy

Location & Overview

The tibialis posterior muscle is the deepest muscle in the posterior compartment of the lower leg. The other deep muscles in the posterior compartment of the lower leg are: the flexor digitorum longus, the flexor hallucis longus and the popliteus. The tibialis posterior is not able to be palpated as it is covered by the large superficial muscles of the lower leg; the gastrocnemius and soleus ^{[1] [2] [3]}.

Origin & Insertion

The tibialis posterior originates from the posterior surface of the upper half of the tibia, the posterior surface of the upper half of the fibula, and the posterior side of the interosseus membrane. The tibialis posterior then continues in an inferior direction down the leg crossing the ankle joint (posterior to the medial malleolus) and inserting to bones underneath of the foot (on the plantar aspect). The insertion points located on the plantar aspect of the foot are: the navicular bone tubercle, medial cuneiform bone, intermediate cuneiform bone, lateral cuneiform bone, cuboid bone; and the bases of the 2nd, 3rd and 4th metatarsal bones ^{[4] [5] [6]}.

Actions

The tibialis posterior is a primary inverter of the foot. The other primary foot inverter of the foot is the tibialis anterior. The tibialis posterior is also able to assist the gastrocnemius, soleus, and plantaris muscles in causing plantar flexion of the foot. The tibialis posterior is also able to support the medial arch of the foot (the tibialis anterior is also able to assist in supporting this medial arch too) ^{[7] [8] [9]}.

Innervation

The tibialis posterior muscle is innervated by the tibial nerve. The tibial nerve is a component of the sciatic nerve originating from the ventral rami of spinal roots L4-S3 ^{[10] [11]}.

Blood Supply

Blood is supplied to the tibialis posterior primarily from the posterior tibial artery. The posterior tibial artery arises from the popliteal artery ^[12].