Question 1

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

Accepted Answer

Contraction of the lateral pterygoid pulls the condyle forward and helps protrude and depress the mandible.Lateral movement occurs when only one lateral pterygoid is contracted.The superior head of the lateral pterygoid functions primarily in what is sometimes called the power stroke.

Question 2

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

Accepted Answer

Depression of the mandible is accomplished by the inferior head of the lateral pterygoid muscle plus the hyoid muscles.This includes the suprahyoid and the infrahyoid muscles.When contracted,the thyrohyoid muscle either lifts the thyroid cartilage and raises the larynx or depresses the hyoid bone.

Question 3

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

Accepted Answer

The hyoid bone,located in the neck,is not a portion of the zygomatic arch.It is a horseshoe-shaped bone suspended beneath the mandible and is unusual because it articulates with no other bone.Its only connection with other bones is by muscles and ligaments.

Question 4

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

Accepted Answer

The fifth cranial nerve,the trigeminal nerve,is the nerve of the first pharyngeal arch.Also note,more specifically,muscles of mastication are innervated by the third part of the fifth cranial nerve,which is called the mandibular division.

Question 5

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

Accepted Answer

Contraction of the digastric,mylohyoid,and geniohyoid muscle depress the mandible.Contraction of the remaining suprahyoid muscle,the stylohyoid,pulls the hyoid bone back and up.

Question 6

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

Accepted Answer

The geniohyoid muscle,a member of the suprahyoid group,does not elevate the mandible.The remaining three selections are muscles of mastication,which elevate,protrude,and retrude the mandible.Muscles of mastication also cause the mandible to move laterally.

Question 7

The larynx moves up and down during swallowing.The thyrohyoid muscle pulls the larynx down.

Accepted Answer

During swallowing the thyrohyoid muscle contracts,elevating the thyroid cartilage of the larynx.Prevention of choking is accomplished by muscular contractions,which move the epiglottis over the opening of the larynx.

Question 8

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

Accepted Answer

The temporal muscle,frequently called the temporalis muscle,has a very wide origin.Contraction of the entire muscle pulls up the coronoid process and elevates the mandible,closing the mouth.

Question 9

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

Accepted Answer

The masseter muscle is probably the most powerful of muscles of mastication.It is not a member of the suprahyoid muscle group.

Question 10

All muscles of mastication insert into the disk of the TMJ.Blood supply to these muscles comes from the maxillary artery,which is a branch of the carotid.

Accepted Answer

Of the four muscles of mastication,only the lateral pterygoid muscle has fibers that insert into the disk of the TMJ.

Question 11

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

Accepted Answer

Sensory nerve supply for these muscles is near the trigeminal nerve nucleus in the upper spinal cord.This can result from pain emanating from the area of the temporomandibular joint.

Question 12

Which muscle of mastication does not have two origins?

Accepted Answer

The temporal muscle has one very wide origin from the entire temporal fossa and the fascia,which covers muscle.The remaining muscles of mastication have two origins.

Question 13

The mylohyoid muscle originates from the mylohyoid line on the medial surface of each side of the maxilla.The left and right muscles fuse into what is known as a raphe.

Accepted Answer

The mylohyoid muscle originates from the mylohyoid line on the medial surface of each side of the mandible.

Question 14

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.

Accepted Answer

It is necessary to palpate beneath the sternocleidomastoid muscle to check for enlarged lymph nodes against the jugular vein.

Question 15

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

Accepted Answer

The temporalis muscle,also called the temporal muscle,has a very wide origin with both anterior and posterior fibers.Contraction of only the posterior fibers results in a horizontal pulling of the coronoid process.This action pulls the mandible backward,referred to as retruding the mandible.

Question 16

Each of the following is a muscle of the suprahyoid group EXCEPT one.Which one is the EXCEPTION?

Accepted Answer

The thyrohyoid muscle is a member of the infrahyoid muscle group.Hyoid muscles are divided into two groups - those above the hyoid bone are called the suprahyoid muscles and those below are called the infrahyoid muscles.

Question 17

Which muscle originates in the upper sternum and inserts into the thyroid cartilage?

Accepted Answer

The thyrohyoid muscle originates from the oblique line on the lateral side of the thyroid cartilage,which serves as the insertion of the sternothyroid muscle.This muscle is a member of the infrahyoid group.

Question 18

Innervation to the digastric muscle is unusual because it has two nerves supplying it.

Accepted Answer

Both the facial and trigeminal cranial nerves supply the digastric muscle.The anterior part of muscle is supplied by the trigeminal nerve and the posterior part is supplied by the facial nerve.

Question 19

The floor of the mouth is formed by which muscle?

Accepted Answer

The mylohyoid muscle forms what is called the floor of the mouth.It is a member of the suprahyoid group whose action is depression of the mandible.

Question 20

The shape of the hyoid bone resembles a

Accepted Answer

The hypoid bone is a horseshoe-shaped bone suspended beneath the mandible,with the open end of the horseshoe pointed posteriorly.

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