3rd CNP
What is the course of the 3rd nerve?- ✅✅ leaves nucleus, moves forwards and
traverses the red nucleus
leaves brainstem and enters the subarachnoid space lateral to the posterior
communicating artery
Then travels forwards and enters the cavernous sinus
separates into superior and inferior division as it enters the orbit
Where is the 3rd nucleus?-✅✅midbrain at the level of the superior colliculus
What can cause a 3rd with pupil in the subarachnoid space?-✅✅aneurysm - PCA
mass/herniation of tentorium cerebelli
cysts
schwannomas or angiomas
infection
What can cause a pupil sparing 3rd in the subarachnoid space?- ✅✅ischaemia
diabetes
hypertension
temporal arteritis
migraine
What fibres control pupil constriction?- ✅✅parasympathetic
What layers of the 3rd are the parasympathetic pupil fibres in- ✅✅outer layers
What type of cause would affect pupils?- ✅✅SOL
maybe diabetic
✅✅vascular causes
What type of causes generally don’t affect pupils?-
What can cause a 3rd in the cavernous sinus?-✅✅vascular lesion - internal carotid
artery aneurysm, thrombosis, carotid cavernous fistula
tumour - pituitary, meningioma, nasopharyngeal carcinoma
infection
inflammation - tolosa hunt syndrome
ischaemia
trauma - skull fracture
What is the course of the 3rd nerve?- ✅✅ leaves nucleus, moves forwards and
traverses the red nucleus
leaves brainstem and enters the subarachnoid space lateral to the posterior
communicating artery
Then travels forwards and enters the cavernous sinus
separates into superior and inferior division as it enters the orbit
Where is the 3rd nucleus?-✅✅midbrain at the level of the superior colliculus
What can cause a 3rd with pupil in the subarachnoid space?-✅✅aneurysm - PCA
mass/herniation of tentorium cerebelli
cysts
schwannomas or angiomas
infection
What can cause a pupil sparing 3rd in the subarachnoid space?- ✅✅ischaemia
diabetes
hypertension
temporal arteritis
migraine
What fibres control pupil constriction?- ✅✅parasympathetic
What layers of the 3rd are the parasympathetic pupil fibres in- ✅✅outer layers
What type of cause would affect pupils?- ✅✅SOL
maybe diabetic
✅✅vascular causes
What type of causes generally don’t affect pupils?-
What can cause a 3rd in the cavernous sinus?-✅✅vascular lesion - internal carotid
artery aneurysm, thrombosis, carotid cavernous fistula
tumour - pituitary, meningioma, nasopharyngeal carcinoma
infection
inflammation - tolosa hunt syndrome
ischaemia
trauma - skull fracture
