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

face The face is the front of an animal's 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 aff ...

. It is supplied by the mandibular branch of the

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

(V). It is important in

mastication Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes. During the mastication process, ...

(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 () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ...

. 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 anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, 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 surfa ...

. The insertion joins the

masseter muscle In human 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 ...

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 (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 tympani muscle. Structure ...

, 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 nerve (CN V). Unlike the other divisions of the trigeminal nerve ( ophthalmic nerve, maxillary nerve) which contain only ...

, 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 thu ...

and the

tensor veli palatini muscle The tensor veli palatini muscle (tensor palati or tensor muscle of the velum palatinum) is a broad, thin, ribbon-like muscle in the head that tenses the soft palate. Structure The tensor veli palatini is found anterior-lateral to the levator v ...

. 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, 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 (plural, : teeth) is a hard, calcification, calcified structure found in the jaws (or mouths) of many vertebrates and used to Mastication, break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with ...

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