Pons
Origin · CN V CN VI CN VII CN VIII
The trigeminal nerve emerges from the lateral mid-pons; abducens, facial and vestibulocochlear nerves leave at the pontomedullary junction, VI medially beside the pyramid and VII and VIII laterally at the cerebellopontine angle. Facial nerve fibres loop around the abducens nucleus to form the facial colliculus in the floor of the fourth ventricle.
Detail
- Gives rise to
- CN V (lateral mid-pons), CN VI (medial pontomedullary junction), CN VII and VIII (lateral pontomedullary junction, cerebellopontine angle)
- Nuclei
- Trigeminal motor and principal sensory nuclei, abducens nucleus, facial nucleus, vestibular and cochlear nuclei; basilar artery supply
When it goes wrong
Ventral pontine infarct or tumour involving the VI and VII fascicles and the corticospinal tract (Millard–Gubler syndrome)
Ipsilateral lateral rectus palsy and lower motor neurone facial weakness with contralateral hemiparesis
Cerebellopontine angle tumour (vestibular schwannoma, meningioma) enlarging against the pons
Unilateral sensorineural deafness and tinnitus first, then absent corneal reflex and facial numbness (V), facial weakness (VII) and ipsilateral limb ataxia
Practise this structure
1 question in the bank tagged Brainstem.