Cranial Nerves Flashcards
Olfactory Nerve (CNI)
Test with coffee and soap.
Noxious odours will stimulate pain fibres.
Impairment can be due to obstruction, damage to nerves or olfactory bulbs.
Optic Nerve (CNII)
Ophthalmoscopic Examination
Ophthalmoscopic Examination
- Dark room and switch on ophthalmoscope light and turn on to large beam of light
- Lens disc is 0 diopters, finger on lens disc to turn easy
- Right hand to see right eye and left hand to see left eye
- Instruct patient to look over your shoulder
- 30 cm away and 15 degrees laterally from the eye
- Shine light and look for red reflex
- Hand on brow and move in towards retina and keep the angle
- Look at optic disc and note for outline, colour and size of cup
- Compare both eyes for symmetry
- Inspect the retina - the arteries and veins coming from disc, fovea and macula
- Change lens to 10 to view anterior eye - opacities in the vitreous humour or lens
Optic Nerve (CNII)
Visual Acuity
Snellen eye chart:
- Stand 20 feet away and do one eye at a time. Bad eye first
- Distance they stand is the numerator.
- Number they can read is the representative they can read at 20/40 half vision.
Optic Nerve (CNII)
Colour Vision
- Ishihara charts
- Red desaturation - look at red and mention any dullness
Can mean optic neuritis
Optic Nerve (CNII)
Visual Fields
- Stand in front of pt and get them to gaze into examiner’s pupils
- Ask pt to close one eye, and examiner closes same eye as the control
- Testing each eye separetly and using an index finger to move in the filed of view, above, below, medially and laterally
- Or you can stand to the side and bring your finger into the field of view for the patient
Optic Nerve (CNII)
Pupillary Light Reflex
Tests the optic and oculomotor nerve
- Direct response to light - pupil constriction
- Consensual response - constriction of opposite pupil
- Swinging flashlight - swing side to side and look for consenual constriction
Optic Nerve (CNII)
Convergence and Accomodation
- Move a pen towards the pt’s eyes and look for convergence, ask them to stop when they lose focus on pen
- Pupils will constrict as object moves closer to cut down rays of light entering the eye
Extraoccular Muscles
- Test each eye separetly and then toegtehr for conjugate movement
- Close one eye and follow the examiners finger as it travels in a big H to test each extraocular muscle of the eye and the nerve thaty supply them
Optokinetic Nystagmus
Moving a strip of parallel stripes in front of the pt’s eyes causing a rhythemic eye movement called nystagmus.
Ask to count the strips as you pull through your hands.
Horizontal and Vertical to be done
Oculocephalic Testing
- Lay pt down and ensure there are no cervical injuries and keep their eyes open
- Normal - eyes will move contralaterally
- Brain injury - eye will move with the movement - doll’s eyes reflex
- Only to be done on unconscious patients
CNV
Facial Sensation and Muscles of Mastication
Trigeminal Nerve
- Sensory (GSA): Facial sensation - close eyes and lightly touch the face at V1, V2, V3 on one side and on the other. Ask for when, where and differences in touch
- Corneal Reflex - try touch cornea with cotton bud, out od site and look for fluttering of the eyelids
- Motor (SVE) - clench jaw and palpate the masseter and temporalis muscles. Keep jaw clsed and resist opening and keep jaw open and resist closing
- Reflexes - Jaw jerk reflex - thumb under lip and tap chin on a downwards angle with mouth hald open. positive is the jaw will close meaning hyper reflexia
CNVII - muscles of facial expression
CNIX - Gag reflex
CX - Palate elevation
CNVII - Facial muscles (SVE) – smile, wrinkle forehead (frontalis), close eyes tight and resist opening (orbicularis oculi), whistle, blow out cheeks (buccinators), show teeth (orbicularis oris), pull platysma muscles
CNIX - gently touch soft palate and pharynx, note any asymmtrical contractions
CNX - say “ahhh” and hold down tongue with a depressor
Articulation (trigeminal, facial, vagus and hypoglossal)
Voice and cough
- hoarseness in cough or voice, can indicate a lesion in the muscles of articulation, the vocal cords themselves, or neuromuscular junction.
Dysdarthria
- abnormal articulation of speech due to the problem with the CNV, VII, IX, X, XII or the NMJ, muscles of articulation, motor contex, cerebullum, basal ganglia or corticobulbar tracts.
- Pt repeats “pa pa pa pa”, “ta ta ta ta” “ga ga ga ga”
Otoscopy
Check ear canal
- Same hand, same side of ear you are checking
- hold like a pencil, rest fingers agains the temple
- pt to tilt head away
- examine the good ear first and ensure they are comfortable
- Pull ear upwards and backwards to straighten ear canal
- put otoscope at the ear but not in the ear,
- Examiner external canel for inflammation, eardrum should be shint and avascular.
- 3 landmark on the membrane to examine
- Malleus and check the manubrium. right ear 2oclock and left ear 11oclock
- light reflex off the umbo - right 4oclock and left 8oclock
- annulus on outr boarder
- inspect the pars tensa and pars flaccida
- check entire membrane and look for fluid or air bubbles
Weber and Rinnes Test
Weber’s Test
- Hold a 512 fork in the centre of pt’s forhead and should pick up sound equally in both ears.
- Conductive loss - tone in the affected ear louder
- Sensorineural hearing loss - tone is louder on the normal side
Rinne Test
- Hold the fork 512 agains the mastoid and then near the EAM. conductiuon in air is usually better but in conductive hearing loss this is reversed. In sensory hearing loss there is just a decrease in hearing for the affected ear.
