Temporomandibular joint
The temporomandibular joint (TMJ) is an atypical synovial joint located between the condylar process of the mandible and the mandibular fossa and articular eminence of the temporal bone. It is divided into a superior discotemporal space and inferior discomandibular space by the TMJ disc (or meniscus).
On this page:
Summary
- location: between mandible and mandibular fossa of squamous temporal bone
-
movement
- upper compartment: protraction, retraction and gliding side-to-side
- lower compartment: opening and closing
- ligaments and tendons: temporomandibular, stylomandibular and sphenomandibular ligaments
- innervation
Gross anatomy
The joint is surrounded by a capsule which is attached inferiorly to the head of the condyle (above the pterygoid fovea - attachment of the inferior belly of the lateral pterygoid muscle) and superiorly to the margins of the mandibular fossa (posteriorly) and articular eminence (anteriorly) of the temporal bone.
Location
- located between the condylar process of the mandible and the mandibular fossa and articular eminence of the temporal bone
Movement
- upper compartment: protraction, retraction and gliding side-to-side
- lower compartment: opening and closing
Ligaments
- major ligament: temporomandibular ligament
- thickened lateral portion of the capsule
- strengthens the TMJ laterally
- minor ligaments: stylomandibular and sphenomandibular ligaments
Articular disc
Between the posterior band of the TMJ disc and the capsule is the retrodiscal zone (or bilaminar zone).
Normally in the closed mouth position, the disc lies above the condyle, with the junction of the posterior band and interlaminar zone within 10° of vertical. Using this measurement, however, up to 33% of asymptomatic individuals have displaced discs. Thus some authors suggest using 30° as the cut-off to improve specificity 1.
The mandibular condyle is centered on the mandibular fossa (also known as the glenoid fossa) when the mouth is closed. When the mouth is open, the condyle moves anteriorly under the center of the articular eminence.
The disc has anterior (A) and posterior (P) bands. The thinner central portion is called the intermediate zone (IZ). The posterior band is normally located directly on top of the condyle (C) when the mouth is closed. The intermediate zone should be between the condyle and the closest portion of the temporal bone in any mouth position.
The posterior aspect of the disc attaches to the bilaminar zone, collagen fibers that pull the disc back when it moves forward.
Blood supply
- branches of the external carotid artery, primarily superficial temporal artery
Innervation
- sensory innervation is from small articular branches of two nerves:
Radiographic features
MRI
The disc has a low signal on all MRI sequences, but it may be possible to see intermediate signal centrally in the anterior and posterior bands.
Related pathology
Related Radiopaedia articles
Anatomy: Head and neck
- skeleton of the head and neck
-
cranial vault
- scalp (mnemonic)
- fontanelle
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
- sphenozygomatic suture
- spheno-occipital suture (not a true suture)
- lacrimomaxillary suture
- nasomaxillary suture
- internasal suture
- basal/internal
- skull landmarks
- frontal bone
- temporal bone
- parietal bone
- occipital bone
- skull base (foramina)
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facial bones
- midline single bones
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- cervical spine
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cranial vault
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- muscles of mastication
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muscles of facial expression
- occipitalis muscle
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- nasal muscles
- buccolabial muscles
- elevators, retractors and evertors of the upper lip
- levator labii superioris alaeque nasalis muscle
- levator labii superioris muscle
- zygomaticus major muscle
- zygomaticus minor muscle
- malaris muscle
- levator anguli oris muscle
- risorius muscle
- depressors, retractors and evertors of the lower lip
- depressor labii inferioris muscle
- depressor anguli oris muscle
- mentalis muscle
- compound sphincter
- orbicularis oris muscle
- incisivus superior muscle
- incisivus inferior muscle
- muscle of mastication:
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
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deep spaces of the neck
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-
arterial supply
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common carotid artery
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common carotid artery
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arterial supply
- innervation of the head and neck
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cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
-
vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
-
vagus nerve (CN X)
- superior laryngeal nerve
- recurrent laryngeal nerve (inferior laryngeal nerve)
- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- third occipital nerve
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cervical plexus
- muscular branches
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ansa cervicalis
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- contribution to the accessory nerve (CN XI)
- cutaneous branches
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cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck