Which statement correctly identifies the insertion of the soleus?

• A. Navicular bone
• B. Base of fifth metatarsal
• C. Calcaneus via plantar aponeurosis
• D. Calcaneus via calcaneal tendon

Answer: (D)

The key idea is where the soleus attaches. The soleus is part of the pair that forms the calcaneal tendon (Achilles tendon) with the gastrocnemius (and often plantaris). This tendon inserts into the calcaneus, specifically the posterior surface/heel tuberosity. This arrangement lets the soleus contribute powerfully to plantarflexion of the ankle, especially when the knee is not bent.

The plantar aponeurosis is a separate fascia running from the calcaneus to the toes, not the insertion point of the soleus. The navicular bone and the base of the fifth metatarsal are attachments for other muscles (for example, tibialis posterior and fibularis muscles), not the soleus. So, the soleus inserts on the calcaneus via the calcaneal tendon.