Which strap muscle is not innervated by the ansa cervicalis?

The mylohyoid muscle is distinguished from other strap muscles because it is primarily innervated by the mylohyoid nerve, which is a branch of the mandibular division of the trigeminal nerve (CN V). This differentiates it from the other strap muscles mentioned, which receive their innervation from the ansa cervicalis. The ansa cervicalis is a loop of nerves that branches from the cervical plexus (C1-C3) and provides motor innervation to the infrahyoid muscles, excluding the mylohyoid.

In comparison, the sternocleidomastoid muscle, while a significant muscle in the neck, is innervated by the accessory nerve (CN XI) rather than the ansa cervicalis. The sternohyoid, sternothyroid, and thyrohyoid muscles, however, are all innervated by the ansa cervicalis, firmly placing the mylohyoid as the only muscle in this context not served by that specific nerve loop. Thus, understanding these innervation patterns is crucial in clinical practice and anatomy.