Nervus intermedius

The nervus intermedius, also known as intermediate nerve of Wrisberg, is a part of the facial nerve (CN VII) which contains somatic sensory, special sensory, and visceral motor (secretomotor) fibres ¹.

Gross anatomy

Nuclei

• superior salivary nucleus
  • parasympathetic supply to the lacrimal and major salivary glands
• nucleus of the tractus solitarius
  • receives taste information from the anterior two-thirds of the tongue (via chorda tympani)
• sensory nuclei of the trigeminal nerve
  • external acoustic meatus and concha of external ear ¹

Course

The nervus intermedius exits the brainstem at the boundary between the pons and the inferior cerebellar peduncle lateral to the motor root of the facial nerve and medial to the vestibulocochlear nerve (in close proximity to the pontomedullary junction). It travels with the motor root of the facial nerve through the cerebellopontine angle towards the internal acoustic meatus where it enters the anterior superior quadrant to travel through the petrous temporal bone. At the geniculate ganglion (at the first genu) it joins the motor root of the facial nerve ^1,2.

Branches

Branches of the facial nerve including ^1,2:

• greater (superficial) petrosal nerve to the pterygopalatine ganglion
• chorda tympani to the submandibular ganglion
• tympanic branches

Radiographic features

MRI

• not visible on CT or 1.5T.5 T MRI
• best appreciated on axial 3T3 T MRI through the cerebellopontine angle travelling towards the internal acoustic canal ³

Related pathology

• facial nerve schwannoma ²
• nervus intermedius neuralgia ⁴

History and etymology

First documented by German anatomist Heinrich August Wrisberg (1736-1808) in 1777, although likely first described by Eustachius in 1563 ^5,6.