Chapter 4: Muscular System (Part 2)

the Infrahyoid muscles include

-omohyoid muscle -sternohyoid muscle -sternothyroid muscle -thyrohyoid muscle

Five paired muscles of the soft palate

-palatoglossus muscle -palatopharyngeus mucsle -levator veli palatini muscle -tensor veli palatini muscle -muscle of the uvula.

Four Intrinsic Tongue Muscles

-superior longitudinal muscle -transverse muscle -vertical muscle -inferior longitudinal muscle

insertion of the Genioglossus Muscle

A few of the most inferior fibers insert on the hyoid bone, but most of the fibers insert into the tongue from its base almost to the apex.

Clinical Note: Oropharyngeal Dysphagia

Abnormalities of the pharynx and/or oral cavity may lead to oropharyngeal dysphagia. The most common symptom of esophageal dysphagia is the inability to swallow solid food.

innervation of the muscles of the soft palate

All of the muscles of the soft palate, except the tensor veli palatini muscle, are innervated by the tenth cranial or vagus nerve through the pharyngeal plexus

Which cranial nerve innervates the infrahyoid muscles?

All of these muscles are innervated by the second and third cervical nerves.

origin of the master muscle

Both heads originate from the zygomatic arch but from differing locations

Insertion of the Medial Pterygoid Muscle

Both heads then pass inferiorly, posteriorly, and laterally, to insert on the medial surface of the mandibular ramus and angle of the mandible, as far superior as the mandibular foramen

insertion of the masseter muscle

Both these heads then pass inferiorly to insert on different parts of the external surface of the mandible:

transverse muscle

Deep to the superior longitudinal muscle and runs in a transverse direction from the median septum to pass outward toward the lateral surface.

action of the Genioglossus Muscle

Different parts of the muscle can protrude or "stick" the tongue out of the oral cavity or depress parts of the tongue surface. The protrusive activity of the muscle helps to prevent the tongue from sinking back and obstructing respiration. Therefore, during general anesthesia, the mandible is sometimes pulled forward to achieve the same effect to ensure complete respiration.

action of the temporalis muscle

If the entire muscle contracts, the main action is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws. If only the posterior part contracts, the muscle moves the lower jaw backward. Moving the lower jaw backward causes retraction of the mandible. Retraction of the jaw often accompanies the closing of the jaws. This muscle also maintains the mandible in its physiologic rest position, allowing for freeway space.

action of the Thyrohyoid Muscle

In addition to depressing the hyoid bone, it raises the thyroid cartilage and larynx.

Action of the Mylohyoid Muscle

In addition to either elevating the hyoid bone or depressing the mandible, this muscle also forms the floor of the mouth and helps elevate the tongue

insertion of the Stylopharyngeus Muscle

It then inserts into the lateral and posterior pharyngeal walls.

Clinical Note:Difficulty Swallowing

Many elderly patients require a feeding tube for dysphagia or difficulty swallowing following strokes (cerebrovascular accidents, CVAs), operations, or neck radiation. New studies suggests that strengthening the suprahyoid muscles with head-raising exercises may allow patients to resume oral feedings.

general action of the infrahyoid muscles

Most of the muscles depress the hyoid bone; some have additional specific actions.

Clinical Note: Tongue Movement Loss

Paralysis affecting one side of the body is a frequent result of stroke (cerebrovascular accident or CVA). The tongue when protruded deviates towards the paralyzed side, which is caused by the greater innervation of the uninvolved side. The muscles of mastication contract equally in ordinary action, although difficulty arises in eating, from food accumulating between the cheek and alveolar process on the paralyzed side. Tongue movement problems are most often caused by nerve damage. However, problems moving the tongue may also be caused by ankyloglossia, a disorder where the band of tissue that attaches the tongue to the floor of the mouth is too short.

Clinical Note:Abnormal Muscle Movement

Tardive dyskinesia refers to abnormal hyperkinetic movements of the muscles of the face, tongue, and neck. It is associated with the use of neuroleptic agents.

action of the masseter muscle

The action of the muscle during bilateral contraction of the entire muscle is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws.

Anterior and Posterior Bellies of the Digastric Muscle

The anterior belly is a part of the anterior suprahyoid muscle group, and the posterior belly is a part of the posterior suprahyoid muscle group.

where is the Lateral Pterygoid Muscle located?

The entire muscle lies within the infratemporal fossa, deep to the temporalis muscle

Intrinsic Tongue Muscles

The four pairs of intrinsic tongue muscles are located entirely inside the tongue. These muscles are named by their orientation to the tongue surface.

Masseter Muscle

The most obvious muscle of mastication, since it is the most superficial and one of the strongest. The muscle is a broad, thick, flat rectangular muscle (almost quadrilateral) on each side of the face, anterior to the parotid salivary gland. Has two heads that differ in depth: the superficial and deep heads.

origin of the Genioglossus Muscle

The muscle arises from the genial tubercles on the medial surface of the mandible

action of the Sternohyoid muscle

The muscle depresses the hyoid bone.

action of the omohyoid muscle

The muscle depresses the hyoid bone.

action of the Sternothyroid Muscle

The muscle depresses the thyroid cartilage and larynx, yet does not directly depress the hyoid bone

action of the hypoglossus muscle

The muscle depresses the tongue.

action of the Geniohyoid muscle

The muscle either elevates the hyoid bone or depresses the mandible.

action of the Stylohyoid Muscle

The muscle either elevates the hyoid bone or depresses the mandible.

action of the digastric muscle

The muscle either elevates the hyoid bone or depresses the mandible.

action of the Stylopharyngeus Muscle

The muscle elevates and simultaneously widens the pharynx.

Action of the Palatoglossus Muscle

The muscle elevates the base of the tongue, arching the tongue against the soft palate, and depresses the soft palate toward the tongue. The muscles on both sides also form a sphincter, separating the oral cavity from the pharynx.

action of the Medial Pterygoid Muscle

The muscle elevates the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws. The medial pterygoid muscle parallels the action of masseter muscle, but the effect is smaller overall.

Which cranial nerve innervates the temporalis muscle?

The muscle is innervated by the deep temporal nerves, branches of the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve.

Which cranial nerve innervates the Geniohyoid muscle?

The muscle is innervated by the first cervical nerve, which is conducted by way of the twelfth cranial or hypoglossal nerve

Which cranial nerve innervates the Lateral Pterygoid Muscle

The muscle is innervated by the lateral pterygoid nerve, a branch of the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve.

Which cranial nerve innervates the masseter muscle?

The muscle is innervated by the masseteric nerve, a branch of the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve.

Which cranial nerve innervates the Medial Pterygoid Muscle

The muscle is innervated by the medial pterygoid nerve, a branch of the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve.

Which cranial nerve innervates the Mylohyoid Muscle

The muscle is innervated by the mylohyoid nerve, a branch of the mandibular nerve (or division) of the fifth cranial or trigeminal nerve

Which cranial nerve innervates the stylohyoid muscle?

The muscle is innervated by the stylohyoid nerve, a branch of the seventh cranial or facial nerve.

origin and insertion of the Muscle of the Uvula

The muscle lies entirely within the uvula of the palate, which is a midline tissue structure that hangs inferiorly from the posterior margin of the soft palate.

action of the Palatopharyngeus Muscle

The muscle moves the palate posteroinferiorly and the posterior pharyngeal wall anterosuperiorly to help close off the nasopharynx during swallowing.

origin of the Hyoglossus Muscle

The muscle originates on both the greater cornu and a part of the body of the hyoid bone.

action of the Levator Veli Palatini Muscle

The muscle raises the soft palate and helps bring it into contact with the posterior pharyngeal wall to close off the nasopharynx during speech and swallowing.

action of the Styloglossus Muscle

The muscle retracts the tongue, moving it superiorly and posteriorly.

action of the muscle of the uvula

The muscle shortens and broadens the uvula, changing the contour of the posterior part of the soft palate. This change in contour allows the soft palate to adapt closely to the posterior pharyngeal wall to help close off the nasopharynx during swallowing.

action of the Tensor Veli Palatini Muscle

The muscle tenses and slightly lowers the soft palate.

origin and insertion of the pharyngeal constrictor muscles

The origin of each muscle is different, although the muscles overlap each other and have similar insertions

insertion of the Mylohyoid Muscle

The right and left muscles then pass inferiorly to unite medially at the mylohyoid raphe, forming the floor of the mouth

Muscles of Tongue

The tongue consists of symmetric halves divided from each other by the median septum, which is a deep tendinous band located within the midline. The median septum corresponds with the median lingual sulcus, a midline depression on the tongue's dorsal surface.

origin and insertion of the extrinsic tongue muscles

These muscles all have differing origins outside the tongue but all their insertions are inside the tongue

action of the Pharyngeal Constrictor Muscles

These muscles raise the pharynx and larynx and help drive food inferiorly into the esophagus during swallowing.

insertion of the Pharyngeal Constrictor Muscles

These muscles then all insert into the median pharyngeal raphe, which is a midline tendinous band of the posterior wall of the pharynx that is itself attached to the base of the skull.

origin of the Styloglossus Muscle

This muscle originates from the styloid process of the temporal bone

origin of the Stylopharyngeus Muscle

This muscle originates from the styloid process of the temporal bone

action of the Suprahyoid Muscles

Two actions associated with mastication result from this muscle contraction. One action of both the anterior and posterior muscles is to cause the elevation of the hyoid bone and larynx if the mandible is stabilized by contraction of the muscles of mastication. This action occurs during swallowing.

Temporalis Muscle

a broad, fan-shaped muscle of mastication on each side of the head that fills the temporal fossa, superior to the zygomatic arch

Genioglossus Muscle

a fan-shaped extrinsic tongue muscle superior to the geniohyoid

Temporal Fossa

a flat, fan-shaped depression on the lateral surface of the skull. It contains the body of the temporalis muscle.

Cervical Muscles: Hyoid Muscles

a horseshoe-shaped bone suspended inferior to the mandible; it does not articulate with any other bone and has only muscular and ligamental attachments through the hyoid muscles.

Levator Veli Palatini Muscle

a muscle mainly located superior to the soft palate.

Muscle of the Uvula

a muscle of the soft palate

Stylopharyngeus Muscle

a paired longitudinal muscle of the pharynx.

Tensor Veli Palatini Muscle

a special muscle that stiffens the soft palate. This muscle is usually active during all palatal movements.

Digastric Muscle

a suprahyoid muscle that has two separate bellies: the anterior and posterior bellies

Stylohyoid Muscle

a thin posterior suprahyoid muscle that has two slips: superficial and deep slips, which are located on either side of the intermediate tendon of the digastric muscle.

Lateral Pterygoid Muscle

aka external pterygoid muscle a short, thick, almost conical muscle of mastication superior to the medial pterygoid. It has two separate heads of origin: the superior and inferior heads. The two heads are separated anteriorly by a slight interval but fuse together posteriorly.

Muscles of Pharynx

aka pharyngeal muscles are involved in speaking, swallowing, and middle ear function. These muscles are responsible for initiating the swallowing process.

action of the muscles of the soft palate

all of these muscles are involved in speaking and swallowing. When these muscles are relaxed, the soft palate extends posteriorly to define the anterior oropharynx. The combined actions of several muscles of the soft palate move the soft palate superiorly and posteriorly to contact the posterior pharyngeal wall that is being moved anteriorly. This movement of both the soft palate and pharyngeal wall brings a separation between the nasopharynx and oral cavity during swallowing to prevent food from entering the nasal cavity while eating.

Mylohyoid Muscle

an anterior suprahyoid muscle deep to the digastric muscle with fibers running transversely between the two mandibular rami

Geniohyoid Muscle

an anterior suprahyoid muscle superior to the medial border of the mylohyoid

Hyoglossus Muscle

an extrinsic tongue muscle.

Styloglossus Muscle

an extrinsic tongue muscle.

Omohyoid Muscle

an infrahyoid muscle lateral to both the sternothyroid and thyrohyoid muscles. This muscle has two separate bellies: the superior and inferior bellies.

Sternohyoid Muscle

an infrahyoid muscle superficial to the sternothyroid as well as the thyroid cartilage and thyroid gland.

Sternothyroid Muscle

an infrahyoid muscle superficial to the thyroid gland

Medial Pterygoid Muscle

another muscle of mastication that is deeper, yet similar, rectangular form to the more superficial masseter. Has two heads due to their differing depth, again similar to the masseter muscle: the deep and superficial heads. However, even with these two differing heads, this is the deepest muscle of mastication.

The median palatine raphe is a surface feature demarcating the deeper median palatine suture between the palatine processes of the maxillae __________ and the horizontal plates of the palatine bones _____________ It spans the palate from the incisive papilla to the uvula. Posteriorly, it is the locus for the origin of this muscle as well as other muscles of the soft palate.

anteriorly; posteriorly.

origin of the posterior Belly of the Digastric Muscle

arises from the mastoid notch, medial to the mastoid process of the temporal bone

Divisions of the tongue

base body dorsal surface lateral surface ventral surfaces apex

The most posterior fibers of the muscle then insert on the

body of the hyoid bone.

infratemporal space

bordered laterally by the medial surface of the mandible and the temporalis muscle.

origin of the inferior pharyngeal constrictor

both the thyroid and cricoid cartilage of the larynx

action of the intrinsic muscles of the tongue

change the shape of the tongue

The superior and inferior longitudinal muscles act together to

change the shape of the tongue by shortening and thickening it and act singly to help it curl in various directions

inferior longitudinal muscle

close to the ventral surface of the tongue and runs in a longitudinal direction from the base to the apex

What are the muscles of mastication responsible for?

closing the jaws, moving the lower jaw forward or backward, and shifting the lower jaw to one side.

The other action associated with mastication results from the _____________ of the anterior suprahyoid muscles, which causes the mandible to ________ and the jaws to open.

contraction; depress

The origin and insertion of each muscle of mastication varies; however, all the muscles of mastication generally originate on the _________ and insert on the __________.

cranium; mandible

Thyrohyoid Muscle

deep to both the omohyoid and sternohyoidmuscles.

The associated movements of the mandible

depression, elevation, protrusion, retraction, and lateral deviation.

superior belly of the omohyoid muscle

divides the inferior part of the anterior cervical triangle into the carotid and muscular triangles. In the posterior cervical triangle, the inferior belly serves to demarcate the subclavian triangle inferiorly from the occipital triangle superiorly.

One action of both the anterior and posterior Suprahyoid muscles is to cause the ___________ of the hyoid bone and larynx if the mandible is stabilized by contraction of the muscles of mastication.

elevation

These muscles of mastication work with the _______________________ _____________ to accomplish these movements of the mandible.

emporomandibular joint

pterygomandibular space

formed by the lateral pterygoid muscle (roof), medial pterygoid muscle (medial wall), and mandibular ramus (lateral wall).

Temporal Space

formed by the temporal fascia covering the temporalis muscle

Palatoglossus Muscle

forms the anterior faucial pillar in the oral cavity, a vertical fold anterior to each palatine tonsil

soft palate

forms the nonbony posterior part of the roof of the mouth or the oropharynx and connects laterally with the tongue.

Palatopharyngeus Muscle

forms the posterior faucial pillar in the oral cavity, a vertical fold posterior to each palatine tonsil

Infrahyoid Muscles

four pairs of hyoid muscles inferior to the hyoid bone.

muscles of mastication

four pairs of muscles that are located deeper within the face than the muscles of facial expression. These muscles are all attached in some manner to the mandible and include: the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles.

origin of the middle pharyngeal constrictor

hyoid bone and stylohyoid ligament

insertion of the Palatopharyngeus Muscle

inserts in the walls of the laryngopharynx and on the thyroid cartilage

insertion of the Hyoglossus Muscle

inserts into the lateral surface of the body of the tongue

insertion of the Palatoglossus Muscle

inserts into the lateral surface of the tongue.

insertion of the Levator Veli Palatini Muscle

inserts into the median palatine raphe, which is a midline tendinous band of the palate.

insertion of the inferior head of the Lateral Pterygoid Muscle

inserts on the anterior surface of the neck of the mandibular condyle at the pterygoid fovea.

insertion of the Thyrohyoid Muscle

inserts on the body and greater cornu of the hyoid bone; it appears as a continuation of the sternothyroid.

insertion of the superior belly of the omohyoid muscle

inserts on the lateral border of the body of the hyoid bone.

Intrinsic muscles are located/originate entirely __________ the tongue.

inside

The muscles of the tongue can be grouped according to their location: the __________ and __________ groups, with the intrinsic and extrinsic tongue of both groups intertwining within the structure of the tongue.

intrinsic; extrinsic

The pharyngeal constrictor muscles form the ___________ and _____________ walls of the pharynx.

lateral; posterior

The transverse and vertical muscles act together to

make the tongue long and narrow.

The tongue has complex movements during __________, _________, and ____________; these movements are a result of the combined action of muscles of the tongue.

mastication, speaking, and swallowing

the tensor veli palatini muscle is supplied / innervated by the

medial pterygoid nerve, a branch of the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve.

The right and left muscles are separated by the tongue's _________ ___________, which underlines the medial lingual sulcus at the surface.

median septum

When the three pharyngeal constrictor muscles overlap, the inferior is ________ superficial.

most

action of the extrinsic muscles of the tongue

move the tongue while suspending and anchoring the tongue to bony structures of the mandible, the styloid process, and the hyoid bone

origin of the Levator Veli Palatini Muscle

muscle originates from the inferior surface of the temporal bone

vertical muscle

muscle runs in a vertical direction from the dorsal surface to the ventral surface in the body

three parts of the pharynx

nasopharynx oropharynx laryngopharynx

Which cranial nerve innervates the Stylopharyngeus Muscle

ninth cranial or glossopharyngeal nerve.

insertion of the superficial head of the masseter muscle

on the lateral surface of the angle of the mandible,

origin of the Tensor Veli Palatini Muscle

originates from the auditory (pharyngotympanic) tube area and the inferior surface of the sphenoid bone

origin of the temporalis muscle

originates from the entire temporal fossa on the temporal bone that is bound superiorly by the inferior temporal line and inferiorly by the infratemporal crest.

origin of the superior head of the Lateral Pterygoid Muscle

originates from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone

origin of the inferior head of the Lateral Pterygoid Muscle

originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone

origin of the (smaller) Superficial head of the Medial Pterygoid Muscle

originates from the lateral surfaces of the pyramidal process of the palatine bone and maxillary tuberosity of the maxilla.

origin of the Geniohyoid muscle

originates from the medial surface of the mandible, near the mandibular symphysis at the genial tubercles, with both muscles in contact with each other

origin of the Mylohyoid Muscle

originates from the mylohyoid line on the medial surface of the mandible.

origin of the Sternohyoid muscle

originates from the posterior and superior surfaces of the sternum, close to where the sternum joins each clavicle

origin of the deep head of the master muscle

originates from the posterior one-third and the entire medial surface of the zygomatic arch partly concealed by the superficial head of the muscle.

origin of the Palatoglossus Muscle

originates from the posterior part of the median palatine raphe, which is a midline tendinous band of the palate

origin of the Sternothyroid Muscle

originates from the posterior surface of the sternum, deep and medial to the sternohyoid, at the level of the first rib. Both groups of the hyoid muscles are mainly attached to the hyoid bone, except for the sternothyroid muscle.

origin of the (larger) Deep head of the Medial Pterygoid Muscle

originates from the pterygoid fossa on the medial surface of the lateral pterygoid plate of the sphenoid bone.

origin of the inferior belly of the omohyoid muscle

originates from the scapula

origin of the superior belly of the omohyoid muscle

originates from the short tendon attached to the inferior belly

origin of the Stylohyoid Muscle

originates from the styloid process of the temporal bone

origin of the superficial head of the master muscle

originates from the zygomatic process of the maxilla, and from the anterior two-thirds of the inferior border of the zygomatic arch.

origin of the Palatopharyngeus Muscle

originates in the soft palate

origin of the Anterior Belly of the Digastric Muscle

originates on the intermediate tendon of the digastric muscle, which is loosely attached to the body and the greater cornu of the hyoid bone

origin of the Thyrohyoid Muscle

originates on the thyroid cartilage

Extrinsic muscles have their origin ___________ the tongue yet have their insertion ___________ the tongue.

outside; inside

insertion of the Stylohyoid Muscle

passes anteriorly and inferiorly to insert on the body of the hyoid bone

insertion of the posterior Belly of the Digastric Muscle

passes anteriorly and inferiorly to insert on the intermediate tendon.

insertion of the inferior belly of the omohyoid muscle

passes anteriorly and superiorly, crossing the internal jugular vein deep to the sternocleidomastoid muscle, where it then attaches by a short tendon to the superior belly

insertion of the Styloglossus Muscle

passes inferiorly and anteriorly to insert into two parts of the lateral surface of the tongue, at the apex and also at the border between the body and base.

insertion of the Tensor Veli Palatini Muscle

passes inferiorly between the medial pterygoid muscle and medial pterygoid plate, forming a tendon near the hamulus of the medial pterygoid plate. The tendon winds around the hamulus, using it as a pulley, then spreads out to insert into the median palatine raphe.

insertion of the superior head of the Lateral Pterygoid Muscle

passes inferiorly to insert on the anterior surface of the neck of the mandibular condyle at the pterygoid fovea of the mandible as well as the anterior margin of the temporomandibular joint disc and capsule.

insertion of the Geniohyoid muscle

passes posteriorly and inferiorly to insert on the body of the hyoid bone

insertion of the Anterior Belly of the Digastric Muscle

passes superiorly and anteriorly to insert onto the digastric fossa on the medial surface of the mandible.

insertion of the Sternohyoid muscle

passes superiorly to insert on the body of the hyoid bone

insertion of the Sternothyroid Muscle

passes superiorly to insert on the thyroid cartilage

The pharyngeal constrictor muscles are all innervated by the ________________ _________

pharyngeal plexus

The superior pharyngeal constrictor muscles of the pharynx and buccinator muscles are attached to each other at the

pterygomandibular raphe

The pharynx is part of both the ____________ and __________ tracts and is connected to both the _______ and ________ cavities.

respiratory; digestive; nasal; oral

Both groups of the hyoid muscles are attached to the hyoid bone, EXCEPT for the __________________ muscle.

sternothyroid

The stylohyoid ligament runs from the tip of the __________ process of the temporal bone to the lesser ________ of the hyoid bone

styloid; cornu

Each digastric muscle demarcates the superior part of the anterior cervical triangle, forming (with the mandible) a _________________ _____________ on each side of the neck; the right and left anterior bellies of the muscle also form a ____________ _______________ ______________

submandibular triangle; midline submental triangle.

Most of the hyoid muscles are in a ____________ position in the neck tissue.

superficial

the three pharyngeal constrictor muscles

superior middle inferior

Suprahyoid Muscles

superior to the hyoid bone. These superior muscles may be further divided according to their horizontal position in relationship to the hyoid bone: being in either the anterior or posterior suprahyoid muscle groups.

the hyoid muscles can be further grouped based on their vertical relationship to the hyoid bone. These groups are the

suprahyoid or infrahyoid muscles

anterior suprahyoid muscle group includes

the anterior belly of the digastric, mylohyoid, and geniohyoid muscles.

origin of the superior pharyngeal constrictor muscle

the hamulus of the medial pterygoid plate, pterygomandibular raphe, and mandible.

the pterygomandibular space is the injection site for what?

the inferior alveolar block.

Which cranial nerve innervates all of the muscles of mastication?

the mandibular nerve (or third division) of the fifth cranial or trigeminal nerve, with each nerve serving one side of the face.

insertion of the deep head of the masseter muscle

the mandibular ramus superior to the angle of the mandible

superior longitudinal muscle

the most superficial of the intrinsic muscles and runs in an oblique and longitudinal direction close to the dorsal surface from the base to the apex

insertion of the temporalis muscle

the muscle passes inferiorly to insert onto the medial surface, apex, and anterior border of the coronoid process of the mandible at the anteriomedial border of the mandibular ramus.

Which cranial nerve innervates the anterior belly of the digastric muscle?

the mylohyoid nerve, a branch of the mandibular nerve (or division) of the fifth cranial or trigeminal nerve

action of the Lateral Pterygoid Muscle

the only muscle of mastication that assists in depressing the mandible, lowering the lower jaw. Depression of the mandible occurs during the opening of the jaws. However, the main action when both muscles contract is to bring the lower jaw forward, thus causing the protrusion of the mandible. Protrusion of the mandible occurs during opening of the jaws. If only one muscle is contracted, the lower jaw shifts to the contralateral side, causing lateral deviation of the mandible.

posterior suprahyoid muscle group includes

the posterior belly of the digastric and stylohyoid muscles.

Which cranial nerve innervates the posterior belly of the digastric muscle?

the posterior digastric nerve, a branch of the seventh cranial or facial nerve

The muscles of the pharynx include:

the stylopharyngeus, pharyngeal constrictors, and muscles of the soft palate

extrinsic tongue muscles

three pairs styloglossus muscle genioglossus muscle hyoglossus muscle

Which cranial nerve innervates the extrinsic tongue muscles?

twelfth cranial or hypoglossal nerve

Which cranial nerve innervates the intrinsic tongue muscles?

twelfth cranial or hypoglossal nerve

Which cranial nerve innervates the muscles of the tongue?

twelfth cranial or hypoglossal nerve

The pharyngeal constrictor muscles consist of three paired muscles based on their _______ relationship to the pharynx.

vertical

The tongue is a thick vascular mass of ___________ muscle surrounded by a mucous membrane that is anchored to the floor of the mouth by the lingual ___________.

voluntary; frenum.