The medial pterygoid muscle (or internal pterygoid muscle) is a thick, quadrilateral muscle of the

face The face is the front of the head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affect th ...

. It is supplied by the

mandibular branch The marginal mandibular branch of the facial nerve arises from the facial nerve (CN VII) in the parotid gland at the parotid plexus. It passes anterior-ward deep to the platysma and depressor anguli oris muscles. It provides motor innervation to m ...

of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

(V). It is important in

mastication Chewing or mastication is the process by which food is comminution, crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mast ...

(chewing).

Structure

The medial pterygoid muscle consists of two heads. The bulk of the muscle arises as a deep head from just above the medial surface of the

lateral pterygoid plate The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a me ...

. The smaller, superficial head originates from the maxillary tuberosity and the pyramidal process of the

palatine bone In anatomy, the palatine bones (; derived from the Latin ''palatum'') are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxilla, they comprise the hard palate. Stru ...

. Its fibers pass downward, lateral, and posterior, and are inserted, by a strong tendinous lamina, into the lower and back part of the medial surface of the ramus and angle of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

, as high as the

mandibular foramen The mandibular foramen is an opening on the internal surface of the ramus of the mandible. It allows for divisions of the mandibular nerve and blood vessels to pass through. Structure The mandibular foramen is an opening on the internal surfac ...

. The insertion joins the

masseter muscle In anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the ...

to form a common tendinous sling which allows the medial pterygoid and masseter to be powerful elevators of the jaw.

Nerve supply

The medial pterygoid muscle is supplied by the

medial pterygoid nerve The medial pterygoid nerve (nerve to medial pterygoid, or internal pterygoid nerve) is a nerve of the head. It is a branch of the mandibular nerve (CN V3). It supplies the medial pterygoid muscle, the tensor veli palatini muscle, and the tensor ...

, a branch of the

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth Cranial nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

, itself a branch of the

(V). This also supplies the

tensor tympani muscle The tensor tympani is a muscle within the middle ear, located in the bony canal above the bony part of the auditory tube, and connects to the malleus bone. Its role is to dampen loud sounds, such as those produced from chewing, shouting, or thund ...

and the

tensor veli palatini muscle The tensor veli palatini muscle (tensor palati or tensor muscle of the velum palatinum) is a thin, triangular muscle of the head that tenses the soft palate and opens the Eustachian tube to equalise pressure in the middle ear. Structure The ten ...

. The medial pterygoid nerve is a main trunk from the mandibular nerve, before the division of the trigeminal nerve - this is unlike the

lateral pterygoid muscle The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid n ...

, and all other muscles of

which are supplied by the anterior division of the mandibular nerve.

Function

The medial pterygoid muscle has functions including elevating the mandible (closing the mouth), protruding the mandible,

(especially for when the

maxillary teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearin ...

and the mandibular teeth are close together), and excursing the mandible (contralateral excursion occurs with unilateral contraction).

Additional images

File:Medial pterygoid muscle animation small.gif, Position of medial pterygoid muscle (red). File:Gray169.png, Left palatine bone. Posterior aspect. Enlarged. File:Gray177.png, Mandible. Inner surface. Side view. File:Gray510.png, Plan of branches of internal maxillary artery. File:Gray778.png, Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion. File:Gray782 updated.png, Mandibular division of trifacial nerve, seen from the middle line. File:Gray1031.png, Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves. File:Slide6che.JPG, Deep dissection. Anterior view. File:Medial pterygoid muscle.jpg, Medial pterygoid muscle File:Medial pterygoid muscle 2.jpg, Medial pterygoid muscle File:Slide7rr.JPG, Medial pterygoid muscle File:Slide1vv.JPG, Medial pterygoid muscle File:Slide13dddd.JPG, Medial pterygoid muscle File:Slide7cece.JPG, Infratemporal fossa. Lingual and inferior alveolar nerve. Deep dissection. Anterolateral view

References

External links

* * {{Authority control Muscles of the head and neck