Cranial Nerves Flashcards
Name the different cranial nerves
- Olfactory,
- Optic,
- Occulomotor,
- Trochlear,
- Trigeminal,
- Abducens,
- Facial
- Vestibulococlear
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypoglossal
How can you examine the optic nerve?
- Optic discs via opathlmoscopy,
- Pupillary reflexes,
- Visual acuity using snellen chart,
- Visual fields and blind spot
What are the functions of the occulomotor nerve
- Motor function: Movement of eyeball and lens accomodation. It innervates inferior oblique, superior, medial and inferior recti muscles and levator palprebrae superioris.
- Parasympathetic. Nuclei is the edinger-westphall. It innervates ciliary and pupillary constrictor muscles causing pupil constriction
Nucleus in midbrain
Describe the appearence of an oculomotor nerve palsy
- pupil will be dilated,
- Ptosis
- Eye will only be able to look down and out
Describe features of the trochlear nerve and the effect of a CNIV palsy
- Innervates superior oblique muscle. which depresses the adducted eye. Nucleus is in midbrain.
- A palsy will result in the eye looking up and in and the head may be tilted to the side away from the lesion
- Diplopia is worse when looking down
Describe features of abducens nerve and the effects of an abducens nerve palsy
- Innervation of lateral rectus muscle. Nucleus in pons
- Palsy will result in inability to abduct the eye and horizontal diplopia. May occur if there is raised ICP
What is intranuclear ophthalmoplegia
- Failure of adduction on the affected side with nystagmus on lateral gaze on the contralateral side.
- Occurs because of a lesion of the medial longitudinal fasciculus (connects the 3rd and 6th CN nerve) which normally allows for synchronisation of eye movement on horizonal plane
- Seen in MS so investigate via MRI of head to look for demyelinating plaques
Describe the presentation and causes of Horner’s syndrome
- It presents with miosis, ptosis, anhidrosis and apparent enopthalmos,
- It is caused by disruption of the ipsilateral cervical/thoracic sympathetic chain. This could be congenital, brainstem stroke, cluster headache, apical lung tumour, MS, cervical rib, carotid artery dissection or syringomyelia
What are the different functions of the trigeminal nerve?
Sensory: Face (ophthalmic, maxillary and mandibular) and general sensation to anterior 2/3rd of tounge.
Motor: Muscles of mastication: Masseter, temporalis, medial and lateral pterygoids.
Nuclei: Pons and medulla
What is herpes zoster ophthalmicus?
Herpes in the distribution of ophthalmic division of the trigeminal nerve. Treated with oral aciclovir
What are the different functions of the facial nerve?
Motor: Muscles of facial expression.
Sensory: Taste to anterior 2/3rd of tongue.
Parasympathetic: Supplies salivary and lacrimal glands causing salivation and lacrimation
Nuclei location: Pons (motor) and medulla (sensory and PSNS)
How can you tell if a patients facial paralysis is an upper or lower motor neuron problem?
- In an UMN lesion the forehead is preserved as it recieved bilateral supply (pt will still be able to lift eyebrows)
- In a LMN lesion then both superior and inferior muscles are affected
How can you test the function of the pons?
Corneal reflex.
Afferent limb - CNV
Efferent limb - CNVII
What are the different functions of the vestibulocochlear nerve
Sensory: Balance. It innervates semi-circular canals.
Sensory: hearing. Innervation of the cochlear
Nucleus located in pons and medulla
What are the different functions of the Glossopharyngeal nerve?
Sensory: Taste to posterior 1/3rd of tongue, innervates pharyngeal wall for swallowing and carotid sinuses for blood pressure control.
Motor: Innervation of pharyngeal muscles and lacrimal glands for swallowing/gag reflex and lacrimation.
Parasympathetic: Saliva production in parotid glands.
Nucleus location: medulla
