Muscles pf Mastication
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Transcript of Muscles pf Mastication
MUSCLES OF MASTICATION
Group 3
MUSCLES OF MASTICATION
The muscles which are required for mastication are known as the muscles of mastication
These muscles help mainly in the movement of the mandible and not the maxilla as maxilla is an integral part of the skull and the mandible being the only movable bone in the skull.
PRIMARY MUSCLES OF MASTICATION
MASSETER MUSCLE
It is one of the main muscle which helps in the process of mastication
-In humans, the masseter is the second most efficient masticatory muscle.
-Its origin and insertion make it very useful for the movement of the jaw and for applying good bite force for mastication.
-Masseter muscle is a powerful muscle because of its Multipennate arrangement of fibers
MASSETER MUSCLE
-The masseter muscle extends from the zygomatic arch to the ramus and body of the mandible.
-The fibers of this muscle are broad, extending from the region of the second molar on the surface of the mandible to the surface of the ramus.The muscle is divided into 2 parts
Superficial Deep
MASSETER MUSCLE
Origin: Superficial layer – anterior 2/3rd of
lower border of zygomatic arch & zygomatic processof maxilla
Middle layer – anterior 2/3rd of deep surface & posterior 1/3rd of lower border of zygomatic arch
Deep layer – deep surface of zygomatic arch
MASSETER MUSCLE
Insertion : Superficial layer –lower part of
lateral surface of ramus of mandible Middle layer –middle part of ramus Deep layer – upper part of the
ramus & coronoid process
MASSETER MUSCLE
The main function of masseter muscle is
Elevation of the mandible lateral movements of the
mandible for efficient chewing and grinding of the food
unilateral chewing Retraction of the mandible
MASSETER MUSCLE
TEMPORALIS MUSCLE
-This is the muscle which helps in elevation of the mandible, It is one of the muscles of mastication.
-It is large shaped in appearance and covers the Temporal area of the skull.
Origin and Insertion: From the Parietal bone of the skull and
is inserted on the coronoid process of the mandible.
TEMPORALIS MUSCLE
Functions: Elevation of the mandible Retraction of the mandible. Crushing of food between the molars. Posterior fibers draw the
mandible backwards after it has been protruded.
It is also a contributor to side to side grinding movement.
TEMPORALIS MUSCLE
LATERAL PTERYGOID MUSCLE
-This is a small muscle which also helps in the mastication process.
-It is divided into 2 heads Origin: Upper head – infratemporal surface
& crest of greater wing of sphenoid bone
Lower head – lateral pterygoid plate
LATERAL PTERYGOID MUSCLE
Insertion : Pterygoid fovea on the anterior surface
of neck of mandible Anterior margin of articular disc &
capsule of TMJ Functions: Depresses the mandible Protrudes it forward for opening of the
jaw Side Movements
LATERAL PTERYGOID MUSCLE
MEDIAL PTERYGOID MUSCLE
-It is a thick muscle of mastication. Origin and Insertion : It Arises from the deep head the
lateral pterygoid plate, and from the maxillary tuberosity.
Insertion is seen on the Medial angle of the Mandible.
MEDIAL PTERYGOID MUSCLE
Functions: Elevates the mandible, Closes the jaw, Helps in side to side movement.
MEDIAL PTERYGOID MUSCLE
ACCESSORY MUSCLES OF MASTICATION
Group 3
SUPRAHYOID MUSCLES
It is the region above or superior to the hyoid bone in the neck.
It includes the digastric, stylohyoid, mylohyoid, and the geniohyoid muscles.
SUPRAHYOID MUSCLES
The digastric muscle double muscle of the throat which is located
under the chin, behind and below the corner of the jaw, immediately in front of the top of the sternocleidomastoid, one for each side of the jaw and neck.
The digastric is made up of an anterior and posterior belly.
The anterior belly extends from the digastric fossa of the mandible
The posterior belly extends from the mastoid notch of the temporal bone.
Digastric muscle
SUPRAHYOID MUSCLES
The stylohyoid muscle muscle located in the neck thin and slender and is attached to the hyoid
bone The muscle lifts the hyoid bone during
swallowing, which gives the characteristic in and out appearance of swallowing
It lifts the base of the tongue up when swallowing.
It is located just in front of the digastric muscle. Which lifts the tongue back when swallowing.
Stylohyoid muscle
SUPRAHYOID MUSCLES
The mylohyoid muscle triangular muscle on each side of the mouth
that is located above the anterior belly of the digastric muscle
extends from the inner surface of the mandible to the hyoid bone
forms the floor of the mouth depresses the mandible and elevates the hyoid It is important in swallowing
Mylohyoid muscle
SUPRAHYOID MUSCLES
The geniohyoid muscle it is a narrow muscle situated superior
to the medial border of the mylohyoid muscle.
acts to raise the hyoid bone and draw it forward and to retract and depress the lower jaw
Geniohyoid muscle
INFRAHYOID MUSCLES
These muscles are often referred to as strap muscles due to their ribbon-like appearance.
They are located inferior to the hyoid bone.
These muscles anchor the hyoid bone and depress the hyoid and larynx during swallowing and speaking.
It includes the sternohyoid, thyrohyoid, and the omohyoid muscles.
INFRAHYOID MUSCLES
The Sternohyoid Muscle This is a thin, narrow, strap muscle that is
superficial except inferiorly where it is covered by the sternocleidomastoid muscle.
Inferior attachment: manubrium of sternum and medial end of clavicle.
Superior attachment: body of hyoid bone. Innervation: C1, C2, C3 from ansa cervicalis. It depresses the hyoid bone after it has been
elevated during swallowing. It also helps to steady the hyoid during
movements of the tongue, larynx and pharynx.
Sternohyoid Muscle
INFRAHYOID MUSCLES
The Thyrohyoid Muscle This muscle appears to be the superior
continuation of the sternothyroid muscle. Inferior attachment: oblique line of thyroid
cartilage. Superior attachment: inferior body of body and
greater horn of hyoid bone. Innervation: C1 via hypoglossal nerve (CN XII). It depresses the hyoid bone and elevates the
larynx. It is mainly responsible for preventing food from
entering the larynx during swallowing (it pulls the larynx and hyoid bone together)
Thyrohyoid Muscle
INFRAHYOID MUSCLES
The Omohyoid Muscle This muscle has two bellies that are united by an
intermediate tendon, which is connected to the clavicle by a fascial sling.
The omohyoid muscle is an important landmark in the neck because it divides the anterior and posterior triangles into smaller triangles.
Inferior attachment: superior border of scapula near the suprascapular notch.
Superior attachment: inferior border of hyoid bone. Innervation: C1, C2, C3 by a branch of ansa
cervicalis. It depresses, retracts and steadies the hyoid during
swallowing and speaking.
Omohyoid Muscle