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.
