Monday, December 7, 2015

Muscles of Mastication

Muscles of Mastication (Chewing) and Their Relationship to TMJ Disorder, Headaches, and Sinus Pain

There are three muscles of mastication (chewing) which can be involved with a host of symptoms. Most notably, these muscles are often involved with TMJ disorder (also referred to as temporomandibular joint disorder, or TMD), but also can be a strong contributing factor to headaches, tooth pain and sensitivity, and sinus pain. In the case of tooth pain and sinus pain, painful trigger points in these muscles can often go undiagnosed and can lead to unnecessary dental or sinus surgery, as the muscles are rarely considered with pain in the teeth or sinuses. In the majority of the cases of dysfunction, patients present with a head forward posture (discussed in a previous blog post) and this should be addressed for long term relief of pain associated with these muscles.

Acupuncture/Traditional Chinese Medicine is one of the best treatments for a host of problems that derive from dysfunction in one or several of these muscles. It can directly target the site of pain and dysfunction while also examining why these muscles are dysfunctional. Beyond that, it can add a different perspective for problems that cause a host of problems for patients.

Fig. 1: The Masseter muscle and commonly used acupuncture points
used to treat pain and dysfunction with this muscle.
The masseter muscle is one of these muscles of the jaw.  The masseter consists of a superficial and deep layer. Both can be palpated (pressed) directly and both are easily accessible with an acupuncture needle (Fig. 1). Trigger points frequently form in this muscle, and they can refer to the teeth (causing pain that is mistaken for problems with the teeth), the eye (contributing to headaches), the ear (contributing to tinnitus or ear ringing).

Fig 2: Masseter Trigger Points with their pain referral patterns. Image from Travell and Simons'
Myofascial Pain and Dysfunction: The Trigger Point Manual. The red indicates where pain is felt
when hypersensitive nodules or trigger points develop in this muscle.
Fig. 3: Lateral and Medial Pterygoids. Image from
Netter's Atlas of Anatomy
The pterygoids are also jaw muscles and consist of the medial and the lateral pterygoids. These muscles cannot directly be pressed except from inside the mouth. Occasionally I release these muscles by putting on surgical gloves and accessing them in just this way. They can also be reached with an acupuncture needle which, due to its thinness, can reach places that a hand cannot. In this case, the needle does not need to access these muscles through the mouth to reach them but can be inserted on the outside and advanced through spaces between two bones to reach painful trigger points (Fig. 3).

The medial pterygoid refers pain deep to the ear and to the throat. This can interfere with swallowing and contribute to soreness in the throat. This muscle also has an interesting relationship to a muscle called the tensor veli palatini, which, when you yawn or open your mouth, pulls the eustachian tube open and allows drainage and pressure normalization of the middle ear. Tightness of the medial pterygoid can block this function and can be a major contributor to ear stuffiness (barohypoacusis) and can contribute to otitis media.
Fig. 4: Lateral pterygoid TrP referral pattern.
Image from Travell and Simons' Myofascial
Pain and Dysfunction: The Trigger Point Manual

The lateral pterygoids refer pain deep into the maxillary sinus and to the TMJ. Pain in this muscle is frequently a contributing factor to sinus pain and/or TMJ dysfunction.

The final muscle involved with chewing is the temporalis muscle which, as the name implies, is in the temple region. Like the masseter, this muscle can be directly pressed and easily accessed with an acupuncture needle. This muscle frequently contributes to headaches.

Fig 5: Temporalis TrP referral pattern. Image from Travell and Simons' Myofascial
Pain and Dysfunction: The Trigger Point Manual 

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