Masseter

This article is currently under review and may not be up to date. Please come back soon to see the finished work! (21/04/2023)

Introduction and overview

The masseter a primary muscle of mastication and it is one of the strongest of human muscles. It is responsible for the elevation of the mandible and some protraction, and also the chewing movement of the mandible at the temporomandibular joint (TMJ). It is a powerful superficial quadrangular muscle that originates from the zygomatic arch and inserts along the angle and lateral surface of the mandibular ramus. In this article, we will explore the anatomy, origin, insertion, and function of the masseter muscle, as well as its role in jaw pain and dysfunction, and therapeutic interventions.

Anatomy

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Function

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Assessment

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Clinical relevance

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Physiotherapy

There are several conventional interventions available for physiotherapy of the masseter muscle dysfunctions, including therapeutic exercise and manual therapy. Therapeutic exercise involves specific exercises that aim to increase the flexibility of the muscles involved in jaw movement; manual therapy aims ischaemic compression by applying pressure to a specific point in the muscle to decrease muscle tension and alleviate pain. In addition to these conventional methods, some unconventional interventions are also possible, such as dry needling. Dry needling involves inserting a thin needle into the trigger point of the muscle to relieve pain and improve function. All techniques can be combined to achieve the best outcomes for patients with masseter muscle dysfunctions.

A randomized controlled trial compared the effects of exercise combined with ischaemic compression and exercise alone on patients with temporomandibular disorders (TMDs). Fifty patients were randomized into two groups, with Group 1 receiving ischaemic compression in addition to exercise, and Group 2 receiving exercise alone. Results showed that both groups had similar effects on range of motion, pain, pain pressure threshold, and functionality at weeks 1 and 4, except for the painless mouth opening and maximum assisted mouth opening values, which were higher in Group 1 at week 1. The study concludes that exercise combined with ischaemic compression and exercise alone have similar effects on patients with TMDs. A RCT study from 2010 aimed to investigate the effects of dry needling on the masseter muscle trigger points in patients with temporomandibular disorders (TMD). The study involved 12 female patients diagnosed with myofascial TMD, who received either deep dry needling or sham dry needling at the most painful point on the masseter muscle trigger point. The results of the study showed that deep dry needling led to significant improvements in pressure pain threshold, mandibular condyle, and pain-free active jaw opening. The researchers concluded that dry needling can be an effective treatment for myofascial TMD, as it improves the pain threshold and jaw function in patients.