Anatomy (motor division)

The motor division of the fifth cranial nerve is smaller than its sensory counterpart. It supplies the muscular derivatives of the first branchial arch.

The motor nucleus resides medial to the main sensory nucleus of the trigeminal nerve in the pons, and it receives cortical input via the corticobulbar tract. From the pontine nucleus, axons leave with the sensory root into the trigeminal ganglion and thence on as the motor root through the foramen ovale. The root enters the infratemporal fossa where it splits to give lower motor neurone branches to the muscles of mastication:

• temporalis
• masseter
• medial and lateral pterygoids

Additionally, there are branches to:

• the middle ear:
  • tensor tympani - dampens excessive movements of the malleus in response to loud noise
  • tensor veli palatini - involved in elevating the soft palate
• mylohyoid muscle } elevate the hyoid
• anterior belly of digastric muscle } bone when swallowing