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TMJ Anatomy

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Description

TMJ shown in the box

The temporomandibular joint (TMJ), or jaw joint, is a synovial joint that allows the complex movements essential for daily function. It is the joint between the condylar head of the mandible and the mandibular fossa of the temporal bone. This system consists of the TMJ, teeth, and soft tissues, and it plays a role in breathing, eating, and speech.[1]

The TMJ is classified as a ginglymoarthrodial joint (also called a ginglymoid-arthrodial join), because it has a rotational movement in the sagittal plane and a translation movement on its own axis.[2] [3] This translation movement allows greater range of motion than rotation alone would permit. [4] These movements are constrained by various passive factors, as well as the passive tension of the ligaments and muscles.[5][6]

Dysfunction of the TMJ can cause severe pain and lifestyle limitation. Temporomandibular disorders (TMD) affects approximately 5-12% of the population, with peak prevalence in adults aged 20-40 years. [7]

Joint Anatomy

Structurally, TMJ it is classified as a synovial joint. Functionally, TMJ is both a hinge (ginglymus) and gliding (arthrodial) joint. It has fibrocartilaginous surfaces and an articular disc that divides the joint into two cavities.[8] 

Capsule - The capsule is a fibrous membrane that surrounds the joint and attaches to the articular eminence, the articular disc and the neck of the mandibular condyle.

Articular disc - The articular disc is a fibrous extension of the capsule that runs between the two articular surfaces of the temporomandibular joint. The disc articulates with the mandibular fossa of the temporal bone above and the condyle of the mandible below. The disc divides the joint into two sections, each with its own synovial membrane. The disc is also attached to the condyle medially and laterally by the collateral ligaments. The anterior disc attaches to the joint capsule and the superior head of the lateral pterygoid. The posterior portion attaches to the mandibular fossa and is referred to as the retrodiscal tissue. [9]

Retrodiscal tissue - Unlike the disc itself, the retrodiscal tissue is vascular and highly innervated. As a result, the retrodiscal tissue is often a major contributor to the pain of temporomandibular disorder, particularly when there is inflammation or compression within the joint. [10]




Ligaments

Several ligaments provide passive stability to the TMJ and limit excessive movement: The temporomandibular ligament runs from the articular tubercle of the zygomatic arch (cheekbone) down to the lateral and posterior border of the mandibular neck, and it has two parts, an outer oblique portion and an inner horizontal portion.
The stylomandibular ligament runs from the styloid process to the angle of the mandible.

The sphenomandibular ligament runs from the spine of the sphenoid bone to the lingula of the mandible.


The otomandibular ligaments consist of:

  • discomalleolar ligament (DML), which arises from the malleus (one of the ossicles of the middle ear) and runs to the medial retrodiscal tissue of the TMJ
  • anterior malleolar ligament (AML), which arises from the malleus and connects with the lingula of the mandible via the sphenomandibular ligament. [11][12]

The otomandibular ligaments may be implicated in tinnitus associated with TMD. [13] A positive correlation has been found between tinnitus and ipsilateral TMJ disorder. [14][15] It has been proposed that a TMJ disorder may stretch the DML and AML, therefore has the potential to affect middle ear structure equilibrium. [16][17][18][19]

Muscles

The primary muscles acting on the TMJ can be categorised by their actions on mandibular movement. For more detailed descriptions of individual muscles, see the Functional Anatomy of the Head and Jaw page.

Tab 1. Muscles of Temporomandibular Joint

Muscles Actions
Temporalis Elevates mandible
Masseter Elevates mandible
Lateral pterygoid Protracts mandible, depresses the mandible, and causes lateral deviation of mandible
Medial pterygoid Works with the masseter to elevate the mandible, aids in protrusion,
Suprahyoid

Digastric

Stylohyoid

Mylohyoid

Geniohyoid

Assist with depression of the mandible. Digastric assist with retraction of the mandible

Adapted from Moore[20]

TMJ Resting Position and Movements

The TMJ permits several types of mandibular movement, each involving coordinated muscle activity and specific condylar positioning:

Resting position: The resting position of the TMJ is with the mouth slightly open, the lips together, and the teeth not in contact. This is in contrast to the closed-pack position in which the teeth are tightly clenched.[8]

Movements: Movements at TMJ include mouth opening (depression), mouth closing (elevation), moving the jaw forwards (protrusion), bringing the jaw backwards (retraction), and moving the jaw side to side ( lateral excursion).

Each of these movements is performed by several muscles working together to accomplish the movement while controlling the position of the condyle within the mandibular fossa. For example, chewing and talking require a combination of jaw movements in multiple directions. [21][22]

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[23]

Nerve Supply

The primary muscles of the temporomandibular joint are innervated by branches of the mandibular nerve (CN V), specifically the motor root of the trigeminal nerve. This includes the muscles of mastication: the masseter, temporalis, medial pterygoid, and lateral pterygoid.

The musculature around the TMJ and the related structures are influenced by the facial nerve (CN VII). Facial nerve branches supply the posterior belly of the digastric and the stylohyoid muscle.

The muscles and surrounding structures of the TMJ are also integrated into the broader musculoskeletal system via innervation from the cervical spinal nerves, specifically C1, C2, and C3. These upper cervical nerves contribute to the innervation of the suprahyoid muscles (the geniohyoid and thyrohyoid muscles) and the infrahyoid muscles. C1, C2, and C3 also contribute to the sensory and motor supply of the deep cervical muscles that influence head and neck posture and impact the resting position and function of the mandible and the TMJ.[20]

References

  1. ↑ Di Fabio RP. Physical therapy for patients with TMD: a descriptive study of treatment, disability, and health status. Journal of Orofacial Pain. 1998 Apr 1;12(2).
  2. ↑ Maini K, Dua A. Temporomandibular Joint Syndrome. 2020 Nov 17. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 31869076.
  3. ↑ Okeson JP. Management of Temporomandibular Disorders and Occlusion. 8th ed. Elsevier; 2019
  4. ↑ Reboredo V. Introduction to the Temporomandibular Joint Course. Plus. 2021.
  5. ↑ Abdi AH, Sagl B, Srungarapu VP, Stavness I, Prisman E, Abolmaesumi P et al. Characterising motor control of mastication with soft actor-critic. Front Hum Neurosci. 2020;14:188.
  6. ↑ Rocabado M. Biomechanical relationship of the cranial, cervical, and hyoid regions. J Craniomandibular Pract. 1983 Jun-Aug;1(3):61-6.
  7. ↑ Kuć J, Szarejko KD, Gołębiewska M. The Prevalence and Overlaps of Temporomandibular Disorders in Patients with Myofascial Pain with Referral-A Pilot Study. Int J Environ Res Public Health. 2021 Sep 18;18(18):9842.
  8. ↑ 8.0 8.1 Magee DJ. Orthopedic physical assessment. 6th ed. Elsevier; 2014
  9. ↑ Miloro, M; Ghali, GE; Larsen, P; Waite, P; Peterson's principles of oral and maxillofacial surgery, Volume 2, Chapter 47, 2004.
  10. ↑ Lee YH. Functional anatomy of the temporomandibular joint and pathologic changes in temporomandibular disease progression: a narrative review. Journal of Korean Dental Science. 2024;17(1):14-35.
  11. ↑ Loughner BA, Larkin LH, Mahan PE. Discomalleolar and anterior malleolar ligaments: possible causes of middle ear damage during temporomandibular joint surgery. Oral Surg Oral Med Oral Pathol. Jul; 68(1):14-22, 1989.
  12. ↑ Rowicki, T; Zakrzewska, J. "A study of the discomalleolar ligament in the adult human." Folia Morphol. (Warsz). 65 (2): 121–125, 2006.
  13. ↑ Dipalma G, Inchingolo AD, Pezzolla C, Sardano R, Trilli I, Di Venere D, Inchingolo F, Palermo A, Inchingolo AM. The Association Between Temporomandibular Disorders and Tinnitus: Evidence and Therapeutic Perspectives from a Systematic Review. J Clin Med. 2025 Jan 29;14(3):881.
  14. ↑ Kuttila, S; Kuttila, M; Le Bell, BY; Alanen, P; Suonpaa, J. Recurrent tinnitus and associated ear symptoms in adults. Int. J. Audiol., 44:164-70, 2005.
  15. ↑ Ren, YF; Isberg, A. Tinnitus in patients with temporomandibular joint internal derangement. Cranio, 13:75-80, 1995.
  16. ↑ Cheynet, F; Guyot, L; Richard, O; Layoun, W; Gola, R. Discomallear and malleomandibular ligaments: anatomical study and clinical applications. Surg. Radiol. Anat., 25:152-7, 2003.
  17. ↑ Eckerdal, O. The petrotympanic fissure: a link connecting the tympanic cavity and the temporomandibular joint. Cranio, 9:15-22, 1991.
  18. ↑ Kim, HJ; Jung, HS; Kwak, HH; Shim, KS; Hu, KS; Park, HD; Park, HW; Chung, IH. The discomallear ligament and the anterior ligament of the malleus: an anatomic study in human adults and fetuses. Surg. Radiol. Anat., 26:39-45, 2004.
  19. ↑ Wright, EF; Bifano, SL. Tinnitus improvement through TMD therapy. J. Am. Dent. Assoc., 128:1424-32, 1997.
  20. ↑ 20.0 20.1 Moore KL, Dalley AF, Agur AM. Clinically oriented anatomy. Lippincott Williams & Wilkins; 2017 Sept 13.
  21. ↑ Saladin, KS; Human Anatomy. New York, NY: McGraw-Hill, 2005.
  22. ↑ Standring, S, Editor, Gray’s Anatomy, 40th edition, Elsevier, Churchill Livingstone, 2008.
  23. ↑ Functional Anatomy of the TMJ. Movements of the TMJ. Available from https://www.youtube.com/watch?v=SCS4MiHJ5Xw [last accessed 07/01/2018]


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