Cranial nerves Flashcards
Which three structures make up the brain stem?
Midbrain, pons and medulla
Which part of the brain are the first and second cranial nerves extensions of?
Forebrain - there is no sheath surrounding them but CSF instead
Where do nerves 3-7 originate from?
Brainstem
Which nerves are purely sensory?
1,2,8
Which nerves are purely motor?
3,4,6,11,12
Which nervous system controls the cranial nerves?
Autonomic
What does the olfactory nerve do?
Smell
Where does the olfactory nerve emerge?
Cribriform plate
How to test the olfactory plate
Change in sense of smell
Injury to olfactory nerve
Unilateral/bilateral anosmia
Function of optic nerve
Vision and pupil reflex
Where does optic nerve emerge?
Optic canal
How to test optic nerve
Snellen chart
Injury to optic nerve
Ipsilateral blindness
Pituitary tumour = tunnel vision
Function of oculomotor nerve
MR, IR, SR, IO
Upper eyelid
Where does the oculomotor nerve exit?
Superior orbital fissure
How to test oculomotor nerve
‘H’ movement
Injury to oculomotor nerve
Ptosis, double vision, divergent quint, dilated pupils
Function of trochlear nerve
Superior oblique muscle
Where does trochlear nerve exit?
Superior orbital fissure
How to test trochlear nerve
Follow finger - bring the eye to the nose and back down
Injury to trochlear nerve
Nystagmus (involuntary eye movement)
Diplopia
Vision converging
What are the three branches of the trigeminal nerve?
Ophthalmic
Maxillary
Mandibular
Function of ophthalmic branch of trigeminal nerve
Sensory function of scalp forehead and nose
Where does the ophthalmic branch of trigeminal nerve exit the skull?
Superior orbital fissure
How to test trigeminal nerve
Corneal light reflex with VII
Assess light touch/pin prick for sensory
Corneal reflex tested using wisp of wool
Clench jaw and open against my hand
Injury of trigeminal nerve
Ipsilateral anesthesia
Paralysis of ipsilateral muscles of mastication
Carcinoma tongue (lingual nerve) cause severe earache
Function of maxillary branch of trigeminal nerve
Sensory: Cheeks, lower eyelid, nasal mucosa, upper lip, upper teeth, palate
Where does the maxillary branch of trigeminal nerve exit the skull?
Foramen rotundum
Function of mandibular branch of trigeminal nerve?
Sensory: anterior 2/3 tongue, skin over mandible and lower teeth
Motor: mastication
Where does the mandibular branch of the trigeminal nerve exit the skull?
Foramen vale
What are the three divisions of the ophthalmic branch of the trigeminal nerve?
Frontal (supraorbital and supratrochlear), lacrimal and nasociliary (eyeball, cornea and conjunctiva)
What nerve can be damaged when the anterior cranial fossa is damaged?
Olfactory
Symptoms of temporal lobe epilepsy
Olfactory hallucinations
Symptoms of frontal lobe tumour
Unilateral anosmia
Can the optic nerve regenerate after division?
No
What happens in the optic chiasma?
Nerves from each eye are shared
Symptoms of retinal/optic lesions
Ipsilateral blindness
What does AFRO stand for?
Acuity
Fields
Reflexes
Opthalmoscopy
What is the MR?
Medial rectus
What is the IR?
Inferior rectus
What is the SO?
Superior oblique
What is the IO?
Inferior oblique
Path of oculomotor nerve
Brain - cavernous sinus - extrinsic ocular muscles
What is ptosis?
Drooping of upper eyelid
Function of abducens
Motor of lateral rectus
Where does abducens exit skull?
Superior orbital fissure
How to test abducens
Follow penlight with eye to all 4 quadrants
Injury to abducens
Nystagmus, diplopia, convergence of vision
Functions of facial nerve
Sensory: taste to anterior 2/3 of tongue
Motor: facial muscles, crying (lachrymal gland), salivating (sublingual and submandibular) and tasting (chorda tympani)
Where does facial nerve exit skull?
Internal acoustic meatus
How to test facial nerve
Raising eyebrows – temporal Scrunching eyes – zygomatic Blow cheeks – buccal Show teeth – mandibular Resist these motions and assess power
Injury to facial nerve
Ramsay-Hunt syndrome: herpes zoster oticus – shingles affects facial nerve involving geniculate ganglion
Shingles rash, facial paralysis, hearing loss
Altered taste perception, saliva and tear production
Function of vestibulocochlear nerve
Hearing and balance
Where does the vestibulocochlear nerve exit the skull?
Internal acoustic meatus
How to test vestibulocochlear nerve
Obscure pt’s ear canal and eyes
Whisper letter and number and ask pt to repeat
Injury to vestibulocochlear nerve
Hearing loss, vertigo, false sense of motion
Function of glossopharyngeal nerve
Sensory: posterior third of tongue, pharynx, middle ear
Motor: stylopharyngeus (palate)
Autonomic: salivary glands
Where does glossopharyngeal nerve exit skull?
Jugular foramen
How to test glossopharyngeal nerve
Sensory part of gag reflex with vagus
Ask to cough and swallow water
Say ahhhhh – look for
Injury to glossopharyngeal nerve
Sensory loss of pharynx
Loss of taste and sensation to posterior 1/3 of tongue
Pharangeal weakness, loss of saliva
Rarely isolated – usually involves X
Function of vagus nerve
Sensory: tympanic membrane, external auditory canal, ear
Motor: palate, pharynx, larynx
Autonomic: afferents from carotid baroreceptors
Where does vagus nerve exit skull?
Jugular foramen
How to test vagus nerve
Pt’s voice quality
Ask them to say ahhhhh – note elevation of soft palate and uvula
Gag reflex
Injury to vagus nerve
Stridor – noisy breathing
Aspiration – inhale into airway
Dys/aphonia – difficulty speaking
If recurrent laryngeal nerve damaged after surgery, cricothyroid muscle still works and can tense muscles in larynx
Function of spinal accessory nerve
Motor: sternocleideomastoid and trapezius, shrug shoulders
Where does spinal accessory nerve exit skull?
Jugular foramen
How to test spinal accessory nerve
Ask pt to shrug shoulders and turn face against your hands
Injury of spinal accessory nerve
Weakness of trapezius - winged scapula
Function of hypoglossal nerve
Intrinsic and extrinsic tongue muscles except palatoglossus
Where does hypoglossal nerve exit skull?
Hypoglossal canal
How to test hypoglossal nerve
Stick out tongue, note fasciculation, deviation and abnormality in muscle
Push against mouth to test resistance
Injury to hypoglossal nerve
Atrophy of tongue on affected side
Ipsilateral paralysis, wasting and deviation when pushed to affected side
UMN lesion in corticobulbar palsy = bilateral paralysis with no wasting
What are the 5 branches of the facial nerve?
Temporal Zygomatic Buccal Mandibular Cervical
Function of utricle
Horizontal movement
Function of saccule
Linear acceleration and gravity