TSM20: TEMPOROMANDIBULAR JOINT
08/10/08
LEARNING OUTCOMES
Describe the clinically relevant anatomy of the temporomandibular joint and that infratemporal fossa
TEMPORAL AND INFRATEMPORAL FOSSAE
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The temporal fossa lies above the zygomatic arch on the lateral surface of the skull
o Primarily contains the temporalis muscle
o Branches of the maxillary nerve (V2) pass through infero-superiorly
The infratemporal fossa is a wedge-shaped area deep to the mandible and inferior to the temporal
bone
o Primarily contains the pterygoid muscles as well as the sphenomandibular ligament
o Maxillary artery arising from the external carotid (terminal branch) passes through it
o Branches of the mandibular nerve (V3), facial nerve (CN VII) and glossopharyngeal nerve (CN
IX) pass through it
The mandibular nerve (V3) is the largest branch of the trigeminal nerve (CN V) and arises from the
trigeminal ganglion in the infratemporal fossa after which it divides into two trunks:
o The anterior division is primarily motor to the muscles of mastication except for the buccal
nerve which is sensory to the skin of the cheek
o The posterior division is primarily sensory to the anterior two-thirds of the tongue and skin of
the temple and chin as well as the lower lip and teeth except for the nerve to mylohyoid
which is motor to the floor of the mouth and tongue
The pterygoid plexus is a venous plexus situated between the medial and lateral pterygoid muscles
o Drains from the nasal and oral cavities, teeth and muscle in the infratemporal fossa
o Distributes to the external and internal jugular veins
o Small veins join plexus to the cranial cavity which provides a possible route for infections to
spread
TEMPOROMANDIBULAR JOINT
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The temporomandibular joint (TMJ) facilitates various movements of the mandible
The joint is synovial between the condylar process of the mandible and the mandibular fossa and
articular tubercle of the temporal bone
The joint cavity is divided into two by a fibro-cartilaginous articular disc
o The lower region allows rotation of the joint i.e. ‘swinging’ the jaw open and closed
o The upper region allows gliding of the joint i.e. protrusion and retraction of the jaw
Opening the jaw fully involves rotation and protrusion of the mandible onto the articular tubercle
Lateral jaw movements are controlled and restricted by accessory ligaments:
o The sphenomandibular and stylomandibular ligaments
MUSCLES OF MASTICATION
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Masster is a principal muscle of mastication and elevates the mandible
o Originates from the zygomatic arch and maxillary process of zygomatic bone
o Inserts onto the lateral surface of the ramus of the mandible
Temporalis is a principal muscle of mastication and elevates and retracts the mandible
o Originates from the superior border of the temporal fossa
o Forms a tendon inferiorly which passes deep to the zygomatic arch
o Attaches to the coronoid process of the mandible
Medial pterygoid is an accessory elevator of the mandible and assists in lateral jaw movements
o Two origins – deep from medial surface of lateral pterygoid plate and superficial from the
tuberosity of the maxilla
o Inserts near the angle of the mandible on its medial surface
Lateral pterygoid is the main muscle involved in protruding the mandible and lateral jaw movements
o Two origins – upper from the inferior surface of the sphenoid bone and lower from the lateral
surface of the lateral pterygoid plate
o Inserts directly on the capsule of the TMJ near the articular disc
All four of these muscles are innervated by branches of the mandibular nerve (V3) arising from the
infratemporal fossa