The temporomandibular joint (TMJ) is the main connection between the skull and the lower jaw. It comprises:
- the participating area of the squamous portion of the temporal bone
- the articular disc within the joint capsule
- the head of mandible
- the surrounding ligaments
This article will examine the temporomandibular joint in detail, providing you with information about its compartments, the ligaments holding it together, together with the vascular supply and innervation.
|Compartments||Superior (translational movement) and inferior compartments (rotational movement)|
Limits/borders - border of mandibular fossa and neck of the mandible above the pterygoid fovea
|Ligaments||Collateral, temporomandibular, stylomandibular, and sphenomandibular ligaments|
|Vascular supply||Deep auricular, superficial temporal, and anterior tympanic arteries|
|Innervation||Mandibular, masseteric, and deep temporal nerves, together with the otic and superior cervical ganglions|
The joint is separated into a superior and an inferior compartment by the articular disc.
- The superior compartment is bordered superiorly by the mandibular fossa of the temporal bone and inferiorly by the articular disc itself. It contains 1.2 mL of synovial fluid and is responsible for the translational movement of the joint.
- The inferior compartment has the articular disc as a superior border and the condyle of the mandible as an inferior border. It is slightly smaller with an average synovial fluid volume of 0.9 mL and allows rotational movements.
Capsule and Ligaments
The joint capsule originates from the border of the mandibular fossa, encloses the articular tubercle of temporal bone and inserts at the neck of mandible above the pterygoid fovea. It is so loose that the mandible can naturally dislocate anteriorly without damaging any fibers of the capsule.
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The TMJ is supported by the following ligaments:
- The medial and lateral collateral ligaments (also known as the discal ligaments) help connect the medial and lateral sides of the articular disc to the same side of the condyle.
- The temporomandibular ligament is located on the lateral aspect of the capsule and its function includes preventing the lateral or posterior displacement of the condyle.
- The stylomandibular ligament arises from the styloid process and attaches to the mandibular angle. It is responsible for allowing the mandible to protrude.
- The sphenomandibular ligament stretches between the spine of the sphenoid bone and the lingula of the mandible. It contributes to the limitation of extensive protrusive movements and jaw opening.
The TMJ is supplied by three arteries. The main supply comes from the deep auricular artery (from the maxillary artery) and the superficial temporal artery (a terminal branch of the external carotid artery). In addition the joint is provided by the anterior tympanic artery (also a branch of the maxillary artery). The venous blood drains through the superficial temporal vein and the maxillary vein.
The mandibular nerve (third branch of the trigeminal nerve) provides the main nerve supply of the TMJ. Additional innervation comes from the masseteric nerve and deep temporal nerves. Parasympathetic fibers of the otic ganglion stimulate the synovial production. Sympathetic neurons from the superior cervical ganglion reach the joint along the vessels and play a role in pain reception and the monitoring of the blood volume.
- The TMJ consists of two compartments: the superior one which is responsible for translational movement and an inferior one which permits rotation movement.
- The joint capsule originates from the mandibular fossa, encloses the articular tubercle of the temporal bone and insert into the neck of the mandible.
- Four ligaments support the TMJ: the collateral, temporomandibular, stylomandibular, and sphenomandibular ligaments.
- The TMJ is vascularized by the deep auricular, superficial temporal, and anterior tympanic arteries.
- The TMJ is innervated by the mandibular, masseteric, and deep temporal nerves, together with the otic and superior cervical ganglions.