Exam 28: Muscles of Mastication, Hyoid Muscles, and Sternocleidomastoid and Trapezius Muscles

Contraction of only the posterior portion of the temporalis muscle retrudes the mandible because this action also depresses the mandible.

Involuntary contraction and spasms of the sternomastoid and trapezius muscles can be caused by migraine headaches. Some malocclusions can also cause such spasms.

The sternocleidomastoid muscle has an origin at the superior border of the scapula. When the muscle contracts it pulls the hyoid bone down.

The muscles of mastication are innervated by the facial nerve.

If the left lateral pterygoid contracts, the mandible will move to the left because one of the lateral pterygoid muscles acting by itself accomplishes lateral excursion.

The temporal muscle has a very narrow origin. Contraction of the entire temporalis elevates the mandible.

Hyoid muscles have a role in depressing the mandible. This includes the suprahyoid and the thyrohyoid muscles.

The muscles of mastication are innervated by the fifth cranial nerve because they develop from the first (mandibular) pharyngeal arch.

The shape of the hyoid bone resembles a

Which muscle of mastication fans out widely at its origin?

The SCM is innervated by which cranial nerve?

All the muscles of mastication are attached to an area of the mandible.

The lateral pterygoid performs each of the following actions upon the mandible EXCEPT one. Which one is the EXCEPTION?

The masseter muscle is probably the most powerful of the muscles of suprahyoid group. When the masseter contracts, it elevates the mandible, which closes the mouth.

Hyoid muscles located above the hyoid bone are called suprahyoid muscles. When contracted, most muscles of this group elevate the mandible.

The mandible is elevated by each of the following EXCEPT one. Which is the EXCEPTION?

Spasms originating from the TMJ can be referred (as pain) to the sternocleidomastoid muscle (SCM).

During an extraoral examination it is necessary to palpate beneath the sternothyroid muscle because enlarged lymph nodes may be lying against the internal jugular vein in the neck.

The insertion of a muscle is attached to the more movable structure.

The hyoid bone, a portion of the zygomatic arch, is unusual because it articulates with no other bone.