Head And Neck: The Cranial Nerves Flashcards
Which foramen does the brainstem pass through?
The foramen magnum
What does the brainstem contain?
Its the location of the majority of cranial nerve nuclei (collections of cell bodies of the nerve fibres)
What is the cavernous sinus?
Formed between the periosteal and meninges layers of the dura
Contains a venous plexus, the internal carotid artery, the occulomotor, tracheal, ophthalmic, abducens and maxillary nerves
Why are dilated pupils the first sign of raised intracranial pressure?
The autonomic fibres of the occulomotor nerve run on the outside therefore are squashed first
This dilates the pupil
What foramen do each of the branches of the trigeminal nerve pass through?
The ophthalmic branch goes through the superior orbital fissure
The maxillary branch goes through the foramen rotundum then the infra orbital foramen
The mandibular branch goes through the foramen magnum
Why can double vision / one eye cross eyed be an early sign of raised intracranial pressure?
The abducens nerve supplies the lateral rectus muscle - ad if paralysed can cause cross eyed or double vision.
The abducens nerve has a long intracranial route so can be easily stretched by raised pressure when it passes under the pons
What is an acoustic neuroma? (Also known as a vestibular schwannoma)
A benign tumour that grows on the vestibulocochlear nerve
It causes hearing problems, tinitis and vertigo
What is the geniculate ganglion?
A collection of neurones of the facial nerve - has motor, sensory and parasympathetic fibres of the facial nerve.
The geniculate ganglion is located in the petrous part of the temporal bone - it gives off 3 branches.
What difference does it make if a pathology occurs before or after the geniculate ganglion?
If the pathology is before the ganglion then all the parasympathetic functions on the facial nerve will be affected
If the pathology occurs after then the greater petrosal nerve is spared and the lacrimal gland is unaffected
Why is there only partial ptosis in hornets syndrome?
The superior levator palpebrae muscle is still innervated by the intact occulomotor nerve - however has lost sympathetic stimulation so droops
