What is temporomandibular joint disorder (tmj/tmd)?

Jaw joint: Tmj stands for temporomandibular joint. It is the joint that connects the lower jaw to the base of the skull at two areas or joints. It sometimes refers to conditions that involve this anatomical area that today are referred to as tmd, temporomandibular disorders, a group of various conditions involving the breakdown of any, some or all of the differing components of the tmj.

Definition: Anything that is outside the normal function of the jaw joint and its related structures. This may or may not involve discomfort and includes but is not limited to clicks, muscle tightness, restriction of opening, muscle soreness, etc, .

My own theory: My exams of TMJ found asymmetric function of masseter muscles, with spasm & relative hypertrophy of muscle on side of disorder, i.e., "crossed muscle syndrome"(after Janda). My theory is that chronic head tilting induced this asymmetry via compensatory proprioceptive-driven excessive dental occlusion on side of head uppermost. Theoretically gum chewing on weak masseter side might be therapeutic.

A group of disorders: TMD, TMJ, TMJ syndrome are synonymous, referring to a group of disorders relating to the temporomandibular joint (jaw joint) and associated disorders. Can be an abnormality of the bones, cartilage, ligaments, or muscles. Complex. TMD mostly managed by dental TMJ specialists. TMJ experts are most commonly, oral surgeons, prosthodontists, and orofacial pain specialists.