The 7th and 8th nerve complex refers to the facial (cranial nerve VII) and vestibulocochlear (cranial nerve VIII) nerves as they emerge together at the cerebellopontine angle. CN VII controls facial expression, taste from the anterior two-thirds of the tongue, lacrimation and salivation; CN VIII mediates hearing and balance. Lesions here—like vestibular schwannomas—cause hearing loss, tinnitus, vertigo and facial weakness.

The eighth cranial nerve is the vestibulocochlear nerve (also called the auditory or acoustic nerve). It has two parts: the cochlear branch for hearing and the vestibular branch for balance. It transmits sound and head-position information from the inner ear to the brainstem. Damage can cause hearing loss, tinnitus, dizziness, vertigo, and balance problems, often assessed with audiology and vestibular testing.

The seventh cranial nerve is the facial nerve. It is a mixed motor, sensory and parasympathetic nerve that controls muscles of facial expression, provides taste from the anterior two‑thirds of the tongue, and supplies lacrimal and some salivary glands. It emerges from the brainstem at the pontomedullary junction; injury causes facial weakness, altered taste and dry eye or mouth.

A brain MRI can reveal structural causes of nerve-related symptoms—e.g., demyelinating plaques (MS), tumors, inflammation, strokes and some cranial nerve lesions—and specialized MR neurography can image larger peripheral nerves. However, MRI won’t detect microscopic or functional nerve abnormalities (small-fiber neuropathy, early metabolic neuropathy); electrodiagnostic tests (EMG/NCS) and clinical evaluation are often needed.

C7 and C8 are cervical nerve roots that contribute to the brachial plexus and mainly supply the forearm and hand. C7 controls elbow extension (triceps), wrist and finger extension, with sensation over the middle finger and the triceps reflex. C8 supplies finger flexion and intrinsic hand muscles, with sensation over the little finger and medial forearm. Together they feed radial, median and ulnar nerve functions.

Cranial nerve VII (facial) controls facial expression muscles, supplies taste to the anterior two-thirds of the tongue, and mediates lacrimation and salivation via parasympathetic fibers; it also carries some sensory input from the external ear. Cranial nerve VIII (vestibulocochlear) has two parts: the cochlear nerve for hearing and the vestibular nerve for balance, spatial orientation, and equilibrium.