The muscles that mastication are associated with motions of the jaw (temporomandibular joint). They are one of the major muscle teams in the head – the other being the muscles of face expression. There are four muscles:

MasseterTemporalisMedial pterygoidLateral pterygoid

The muscles of mastication construct from the first pharyngeal arch. Thus, they are innervated by a branch of the trigeminal nerve (CN V), the mandibular nerve.

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In this article, we shall look at the anatomy that the muscle of mastication – your attachments, actions, and innervation.

(NB: it is vital to note that every the muscle mentioned right here are bilateral structures).

Masseter

The masseter muscle is the most an effective muscle of mastication. The is quadrangular in shape and has two parts: deep and also superficial.

The totality of the muscle lies superficially to the pterygoids and temporalis, extending them.

Actions: Elevates the mandible, closeup of the door the mouth.Innervation: Mandibular nerve (V3).
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Fig 1 – The masseter muscle. Only the superficial head is visible


Temporalis

The temporalis muscle originates from the temporal fossa – a shallow depression on the lateral aspect of the skull. The muscle is spanned by difficult fascia which can be harvested surgically and also used to repair a perforated tympanic membrane (an operation recognized as a myringoplasty).

Attachments: Originates from the temporal fossa. That condenses right into a tendon, i beg your pardon inserts onto the coronoid procedure of the mandible.Actions: Elevates the mandible, close up door the mouth. Additionally retracts the mandible, pulling the jaw posteriorly.Innervation: Mandibular nerve (V3).
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Fig 2 – The temporalis muscle.


Medial Pterygoid

The medial pterygoid muscle has actually a quadrangular form with two heads: deep and superficial. That is situated inferiorly to the lateral pterygoid.

Attachments:The superficial head originates from the maxillary tuberosity and also the pyramidal procedure of palatine bone.The deep head originates indigenous the medial element of the lateral pterygoid bowl of the sphenoid bone.Both heads connect to the ramus the the mandible near the angle of mandible.Actions: Elevates the mandible, closing the mouth.Innervation: Mandibular nerve (V3).

Lateral Pterygoid

The lateral pterygoid muscle has a triangular form with two heads: superior and inferior. It has actually horizontally orientated muscle fibres, and thus is the major protractor that the mandible.

Attachments:The superior head originates from the better wing of the sphenoid.The inferior head originates from the lateral pterygoid plate of the sphenoid.The two heads converge into a tendon i m sorry attaches come the neck the the mandible.Actions: acting bilaterally, the lateral pterygoids protract the mandible, advertise the jaw forwards. Unilateral activity produces the ‘side come side’ movement of the jaw.Note: convulsion of the lateral pterygoid will create lateral activity on the contralateral side. Because that example, contraction of left lateral pterygoid will deviate the mandible to the right.

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Innervation: Mandibular nerve (V3).