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
Subscapularis muscle Subscapularis muscle The subscapularis is a large triangular muscle which fills the subscapular fossa and inserts into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint. It arises from its medial two-thirds and from the lower two-thirds of the groove on the axillary border (subscapular fossa) of the scapula. Some fibers arise from tendinous laminae, which intersect the muscle and are attached to ridges on the bone; others from an aponeurosis, which separates the muscle from the teres major and the long head of the triceps brachii. The fibers pass laterally and coalesce into