Trigeminal Nerve Innervation of Cheek and Tragus
Yes, the trigeminal nerve innervates the cheek through its maxillary (V2) and mandibular (V3) divisions, but the tragus receives sensory innervation primarily from cervical nerves (C2-C3 via the great auricular nerve) and the auriculotemporal branch of the mandibular nerve (V3), not from the trigeminal nerve as a primary source.
Anatomical Distribution of Trigeminal Nerve Branches
The trigeminal nerve divides into three main branches that provide sensory innervation to distinct facial regions 1:
- V1 (Ophthalmic nerve): Exits via the supraorbital foramen and provides sensory innervation to the upper face and forehead 1
- V2 (Maxillary nerve): Originates from the infraorbital foramen and innervates the midface, including the cheek region 1
- V3 (Mandibular nerve): Innervates the mandibular and temporal regions 1
Cheek Innervation
The cheek is definitively innervated by the trigeminal nerve, specifically through the maxillary division (V2). 1
- The V2 maxillary nerve provides the primary sensory innervation to the midface region, which encompasses the cheek area 1
- This sensory distribution is part of the trigeminal nerve's role in providing general sensation to the face, scalp, nasal cavity, oral cavity, and teeth 2, 3
Tragus Innervation - Important Caveat
The tragus (the small cartilaginous projection of the external ear) has a more complex innervation pattern that extends beyond pure trigeminal distribution:
- While the auriculotemporal branch of V3 (mandibular division) does contribute to some anterior auricular sensation, the tragus primarily receives innervation from the great auricular nerve (C2-C3 cervical plexus)
- This is a common clinical pitfall when assessing facial sensory deficits, as the ear region represents a transition zone between trigeminal and cervical nerve territories
Clinical Implications
When evaluating trigeminal neuropathy, imaging should cover the entire course of the nerve from brainstem to peripheral branches 1:
- Cheek sensory deficits clearly indicate V2 (maxillary) involvement and warrant investigation of the infraorbital foramen, pterygopalatine fossa, and cavernous sinus 1
- Tragus sensory changes should prompt consideration of both V3 mandibular nerve pathology and cervical nerve involvement, depending on the precise distribution pattern
- MRI is the preferred imaging modality for investigating trigeminal nerve pathology 3