the teeth are fully interdigitated is called the median occlusal position.6 Temporomandibular Joints Resting position: Mouth slightly open, lips together, teeth not in contact Close-packed position: Teeth tightly clenched Capsular pattern: Limitation of mouth opening The temporomandibular joints actively displace only anteriorly and slightly laterally. When the mouth is opening, the condyles of the joint rest on the disc in the articular eminences, and any sudden movement, such as a yawn, may displace one or both condyles forward. As the mandible moves forward on opening, the disc moves medially and posteriorly until the collateral ligaments and lateral pterygoid stop its movement. The disc is then seated on the head of the mandible, and both disc and mandible move forward to full opening. If this seating of the disc does not occur, full range of motion at the temporomandibular joint is limited. In the first phase, mainly rotation occurs, primarily in the inferior joint space. In the second phase, in which the mandible and disc move together, mainly translation occurs in the superior joint space.7 The hyoid bone, found in the anterior throat region, is sometimes referred to as the skeleton of the tongue.6 It serves as an attachment for the extrinsic tongue muscles and infrahyoid muscles and, by so doing, provides reciprocal stabilization during swallowing and through its muscle attachments can affect cervical and even shoulder function. Figure 4-4 outlines the effect of a forward head posture and the relation to the hyoid bone and related muscles. The temporomandibular joints are innervated by branches of the auriculotemporal and masseteric branches of the mandibular nerve. The disc is innervated along its periphery but is aneural and avascular in its intermediate (force-bearing) zone.