Mandibular division of the trigeminal nerve (V3)
Division or branch · CN V3 Mixed
The only mixed trigeminal division: the sensory root from the ganglion and the entire motor root of V unite just below the foramen ovale in the infratemporal fossa. Sensory to the lower face, lower teeth, chin, anterior two-thirds of the tongue (general sensation), floor of the mouth, temporomandibular joint and part of the ear; motor to the muscles of mastication and four smaller muscles.
Traced from the start
- Pons
- Trigeminal nerve (CN V)
- Foramen ovale
- Mandibular division of the trigeminal nerve (V3)
Detail
- Sensory
- Chin, lower lip, lower teeth and gum (inferior alveolar → mental nerve); anterior two-thirds of tongue and floor of mouth (lingual nerve, which also carries chorda tympani fibres); cheek mucosa and skin (buccal); temple, auricle, external auditory meatus and temporomandibular joint (auriculotemporal)
- Motor
- Masseter, temporalis, medial and lateral pterygoids, tensor tympani, tensor veli palatini, mylohyoid, anterior belly of digastric
- Ganglion
- Otic ganglion on its medial side: parasympathetic relay from IX (lesser petrosal) whose fibres ride the auriculotemporal nerve to the parotid
- Reflex
- Jaw jerk: afferent and efferent V3, absent or normal in health, brisk with bilateral upper motor neurone (pseudobulbar) lesions
When it goes wrong
Lower motor neurone lesion of the motor root (skull base tumour, perineural spread from a facial cancer)
Jaw deviates towards the weak side on opening because the opposite lateral pterygoid pulls the mandible across unopposed, with wasting of masseter and temporalis on that side
Lingual nerve injury during lower third-molar extraction
Numbness of the same side of the anterior tongue and floor of mouth with loss of taste there, because the chorda tympani fibres travel with it
Inferior alveolar nerve injury from a mandibular fracture through the canal, implant placement or sagittal split osteotomy
Numb lower lip and chin (mental nerve territory); a numb chin without trauma in an adult suggests malignant infiltration of the mandible or skull base
Temporomandibular joint dysfunction or a carious lower molar irritating the auriculotemporal or inferior alveolar nerve
Referred ear pain with a normal otoscopy
Practise this structure
1 question in the bank tagged Trigeminal Nerve.