Gastrocnemius muscle insertion via the Achilles tendon. The plantaris muscle and a portion of its tendon run between the two muscles, which is involved in "locking" the knee from the standing position. Since the anterior compartment of the leg is lateral to the tibia, the bulge of muscle medial to the tibia on the anterior side is actually the posterior compartment. The soleus is superficial to the mid-shaft of the tibia. 10% to 30% of individuals have a sesamoid bone called the "fabella" in the lateral (outer) head of gastrocnemius muscle. Along with the soleus muscle, the gastrocnemius forms half of the
Navicular bone and laterally with the cuboid. It is the last of the foot bones to start ossification and does not tend to do so until the end of the third year in girls and the beginning of the fourth year in boys, although a large range of variation has been reported. The tibialis posterior is the only muscle that attaches to the navicular bone. The main portion of the muscle inserts into the tuberosity of the navicular bone. An accessory navicular bone may be present in 2–14% of the general population. The human navicular is not a commonly broken bone. The