Lateral pterygoid muscle

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Lateral pterygoid muscle

The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed (labeled as "pterygoideus externus", visible in pink at center)

Sagittal section of the temporomandibular joint (labeled as "pterygoideus externus", visible in gray at bottom right)
Latin	Musculus pterygoideus lateralis, musculus pterygoideus externus
Gray's	p.386
Origin	Great wing of sphenoid and pterygoid plate
Insertion	Condyloid process of the mandible
Artery	Pterygoid branches of maxillary artery
Nerve	Lateral pterygoid nerve from the mandibular nerve
Actions	depresses mandible, protrude mandible, side to side movement of mandible
MeSH	Pterygoid+Muscles

The lateral pterygoid (or external pterygoid) is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.

Origin and insertion

The upper/superior head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate.

Inferior head inserts onto the neck of condyloid process of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule of the temporomandibular joint.

Innervation

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

Function

The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible. A concerted effort of the lateral pterygoid muscles acts in helping lower the mandible and open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids.

Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid and geniohyoid muscles.

Additional images

Sphenoid bone. Anterior and inferior surfaces.
Mandible. Inner surface. Side view.
Plan of branches of internal maxillary artery.
Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion.

External links

-73793457 at GPnotebook
LUC lpte
lesson4 at The Anatomy Lesson by Wesley Norman (Georgetown University) (musclesofmastication2)
Mnemonic medicalmnemonics.com 70
Roche Lexicon - illustrated navigator, at Elsevier 25420.000-1
Cross section at tufts.edu

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)

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