Triceps surae muscle Triceps surae muscle The triceps surae is a pair of muscles located at the calf - the two-headed gastrocnemius and the soleus. These muscles both insert into the calcaneus, the bone of the heel of the human foot, and form the major part of the muscle of the posterior leg, commonly known as the calf muscle. The triceps surae is connected to the foot through the Achilles tendon, and has 3 heads deriving from the 2 major masses of muscle. The triceps surae is innervated by the tibial nerve, specifically, nerve roots L5–S2. Contraction of the triceps surae induce plantar
Stapedius muscle of the facial nerve, the stapedius is paralyzed and hyperacusis may result. Like the stapes bone to which it attaches, the stapedius muscle shares evolutionary history with other vertebrate structures. The mammalian stapedius evolved from a muscle called the depressor mandibulae in other tetrapods, the function of which was to open the jaws (this function was taken over by the digastric muscle in mammals). The depressor mandibulae arose from the levator operculi in bony fish, and is equivalent to the epihyoidean in sharks. Like the stapedius, all of these muscles derive from the hyoid arch and are innervated by cranial