Medial pterygoid muscle

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Medial pterygoid

The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed. (Internus is visible at center bottom.)

The otic ganglion and its branches. (Pterygoideus internus labeled at bottom right.)
Latin	musculus pterygoideus medialis, musculus pterygoideus internus
Gray's	p.387
Origin	deep head: medial side of lateral pterygoid plate behind the upper teeth superficial head: pyramidal process of palatine bone and maxillary tuberosity
Insertion	medial angle of the mandible
Artery	pterygoid branches of maxillary artery
Nerve	mandibular nerve via nerve to medial pterygoid
Actions	elevates mandible, closes jaw, helps lateral pterygoids in moving the jaw from side to side
MeSH	Pterygoid+Muscles

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

The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.

Origin and insertion

It 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 smaller, superficial head originates from the maxillary tuberosity and the pyramidal process of the palatine bone.

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, as high as the mandibular foramen. The insertion joins the masseter muscle to form a common tendinous sling which allows the medial pterygoid and masseter to be powerful elevators of the jaw.

Innervation

Unlike the lateral pterygoid and all other muscles of mastication which are innervated by the anterior division of the mandibular branch of the trigeminal nerve, the medial pterygoid is innervated by the main trunk of the mandibular branch of the trigeminal nerve (V), before the division.

Actions

Given that the origin is on the medial side of the lateral pterygoid plate and the insertion is from the internal surface of the ramus of the mandible down to the angle of the mandible, its functions include:

Elevation of the mandible (closes the jaw)
Minor contribution to protrusion of the mandible
Assistance in mastication
Excursion of the mandible; contralateral excursion occurs with unilateral contraction.

Additional images

Position of medial pterygoid muscle (red).
Left palatine bone. Posterior aspect. Enlarged.
Mandible. Inner surface. Side view.
Plan of branches of internal maxillary artery.
Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion.
Mandibular division of trifacial nerve, seen from the middle line.
Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves.
PTERYGOID MEDIAL MUSCLEDeep dissection.Anterior view.

Dissection images
Medial pterygoid muscle Medial pterygoid muscle Medial pterygoid muscle Medial pterygoid muscle Medial pterygoid muscle Infratemporal fossa. Lingual and inferior alveolar nerve. Deep dissection. Anterolateral view

External links

Wikimedia Commons has media related to Medial pterygoid muscles.

LUC mpte
-1483079600 at GPnotebook
Mnemonic medicalmnemonics.com 70
Roche Lexicon - illustrated navigator, at Elsevier 25420.000-1

This article incorporates text from a public domain edition of Gray's Anatomy.

List of muscles of head and neck: the head (TA A04.1, GA 4.378)

Extraocular (CN III, IV, VI)

oblique (inferior, superior) · rectus (superior, inferior, medial, lateral) · levator palpebrae superioris (superior tarsal)

Mastication (CN V3)

masseter · temporalis (sphenomandibularis) · pterygoid (lateral, medial)

fascia: Masseteric fascia · Temporal fascia · Deep portion: cementomaxillary tendon · Superficial portion: cementomandibular tendon

Facial (CN VII)

Ear	auricular (anterior, superior, posterior) · temporoparietalis

Scalp/eyelid	occipitofrontalis (occipitalis, frontalis) · orbicularis oculi (depressor supercilii) · corrugator supercilii fascia: Galea aponeurotica

Nose	procerus · nasalis (dilatator naris) · depressor septi nasi · levator labii superioris alaeque nasi

Mouth	levator anguli oris · levator labii superioris · zygomaticus (major, minor) orbicularis oris · risorius · buccinator depressor anguli oris · depressor labii inferioris · mentalis

Palate/fauces (CN IX, X, XI)
(except TVP=V3)

veli palatini (tensor, levator) · musculus uvulae · palatopharyngeus (to pharynx) · palatoglossus (to tongue)

Tongue (CN XII)

extrinsic (genioglossus, hyoglossus/chondroglossus, styloglossus, and palatoglossus [CN X]) · intrinsic (superior longitudinal, inferior longitudinal, transverse, vertical)

M: MUS, DF+DRCT

anat (h/n, u, t/d, a/p, l)/phys/devp/hist

noco (m, s, c)/cong (d)/tumr, sysi/epon, injr

proc, drug (M1A/3)

Also it elevates mandible.

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