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Anatomy Overview

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MUSCLE ACTIONS OF THE TEMPOROMANDIBULAR JOINT
TABLE KEY:    Primary movers    Secondary movers
Sagittal Plane (rotation) Elevation (closing mouth) Depression (opening mouth)
 

Temporalis

Masseter

Medial pterygoid

Lateral Pterygoid

Digastric

Stylohyoid

Mylohyoid

Geniohyoid

Omohyoid

Sternohyoid

Sternothyroid

Thyrohyoid

Platysma

Sagittal Plane (translation) Protrusion Retraction
 

Lateral Pterygoid

Masseter

medial pterygoid

Temporalis

Masseter

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TEMPOROMANDIBULAR JOINT MUSCLE ATTACHMENTS
Muscles Proximal Attachment Distal Attachment
Temporalis Broad attachment to floor of temporal fossa Narrow attachment to coronoid process and anterior border of ramus of mandible
Masseter Quadrate muscle attaching to inferior border and medial surface of the zygomatic arch Angle and lateral surface of ramus of mandible
Lateral Pterygoid Triangular two-headed muscle from infratemporal surface and crest of greater wing and lateral pterygoid plate of sphenoid Superior head attaches primarily to joint capsule and articular disc of temporomandibular joint; inferior head attaches primarily to condyle of mandible
Medial Pterygoid Quadrangular two-headed muscle from medial surface of lateral pterygoid plate, palatine bone, and maxilla Medial surface of ramus of mandible
Digastric (suprahyoid) Inner surface of anterior body of mandible (anterior belly); mastoid process of temporal bone (posterior belly) Hyoid bone
Stylohyoid (suprahyoid) Styloid process of temporal bone Hyoid bone
Mylohyoid (suprahyoid) Medial surface of mandible Hyoid bone
Geniohyoid (suprahyoid) Inner surface of anterior body of mandible Hyoid bone
Omohyoid (infrahyoid) Superior surface of scapula Hyoid bone
Sternohyoid (infrahyoid) Manubrium of sternum Hyoid bone
Sternothyroid (infrahyoid) Posterior surface of manubrium of sternum Thyroid cartilage
Thyrohyoid (infrahyoid) Thyroid cartilage Hyoid bone

Introduction

The temporomandibular (TM) joint is unique in both structure and function. Structurally, the mandible is a horseshoe-shaped bone (Fig. 6–1) that articulates with the temporal bone at each of its posterosuperiorly located condyles and produces two distinct but highly interdependent articulations. Each TM joint contains a disc that separates the joint into an upper and a lower articulation. Functionally, mandibular movement involves concurrent movement in the four distinct joints (two per TM joint), resulting in a complex structure that moves in all planes of motion to achieve normal function.

A discussion of the structure and function of the TM joint will allow the reader to appreciate and understand its unique features, its relationship with the cervical spine, and the impact of impairments and pathologies of the TM joint. Although the purpose of this chapter is to discuss the normal function and structure of the TM joint, TM disorders are a common subgroup of orofacial pain disorders.1 This chapter will introduce some of the common conditions that involve deviations of normal structure.

Structure and Function of the TM Joint

Structure

Articular Structures

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