CN I - OLFACTORY
Proper way to test CN 1 (Olfactory Nerve)
o Proper way to test: close the patient’s eyes and waft the bottle. Don’t let the patient inhale directly from the bottle because small particles may be carried (i.e. when using coffee powder)
o Test one nostril at a time, giving a few minutes in between because smell develop tolerance very fast
Examination Proper: CN I
Examine Nostril Separately (Occlude the other) ↓ With the patient’s eyes closed and one nostril occluded bring the test substance near the open one ↓ Ask patient to sniff and identify ↓ Repeat on the other side ↓ Compare 2 sides
CN II: OPTIC
Testing of Visual Acuity
Test each eye separately. The Pt keeps eye glasses on. Although glasses improve acuity by correcting for a refractive error, they do not improve acuity impaired.
Examination Proper: CN II OPTIC
Central Vision/Visual Acuity – use a Snellen or Jaeger Chart
o Distance 20ft or 6m
o Jaeger chart held 14 inches or 35.5cm
o Use pinhole
Testing of Visual Fields (by confrontation)
Testing of Visual Fields (by confrontation) 2
Any reflex observed on one side of the body when the other side has been stimulated. (i.e. Constriction of the pupil when one eye was lighted)
Consensual reflex
Testing: Fundoscopy
Testing: Fundoscopy 2
*Right eye of the patient will be seen by the right eye of the doctor. The doctor must be on the side of the patient para di magkiss
Examination Proper: CN II OPTIC (Fundoscope)
Use an Opthalmoscope ↓ Check if the gadget is in adequate setting ↓ Approach the patient from the side (you’ll see something red-orange reflex: those are your arteries and veins) ↓ Follow the red-orange reflex ↓ Look for hemorrhages
CN II and III: OPTIC AND OCCULOMOTOR (Pupillary light reflex (Use 2 lights))
CN III, IV and VI – OCULOMOTOR, TROCHLEAR and ABDUCENS
Test the extra ocular eye movements
o CN VI innervates the lateral recti (LR6)
o CN IV innervates the superior oblique muscles (SO4)
o CN III innervates all other muscles – the medial recti, superior and inferior recti and the inferior oblique muscle
Examination Proper: CN III, IV, and VI
Test both eyes ↓ Ask the patient to follow your finger ↓ Move your finger up, down and sideways ↓ Report whether the patient can’t look up, down or sideway
CN V - TRIGEMINAL
CN V: Trigeminal Nerve
Motor (Strength):
o Check chewing movements. (What are the muscles innervated? TIME! Temporalis, Internal pterygoid, Masseter, External pterygoid)
Sensation:
o Test the forehead (Opthalmic), cheeks (Maxillary), and jaw (Mandibular)on each side for pain sensation. If you find an abnormality, confirm it by testing temperature sensation. Two test tubes, filled with hot and ice-cold water, are the traditional stimuli.
Examination Proper: CN V Sensory
Ask patient to close the eyes ↓ Check for all part of face sensation ↓ Check if there are equal sensations (compare both sides)
Corneal (Blink) reflex
DIFFERENTIAL DIAGNOSIS
What if right side is stimulated but it is the left eye that blinks? Where is the problem (what part of the reflex arc has the problem – motor arc or sensory)? Motor! CN7!
What if the stimulation is applied but neither eye blinked? Sensory problem! CN5!
With the patient’s jaw sagging loosely open, the examiner rests a finger across the tip and strikes it a crisp blow.
Jaw Jerk
Exaggerated reaction in jaw jerk test may indicate problem in the __.
pons
Examination Proper: CN V Motor (jaw jerk)
Ask patient to bite hard ↓ Palpate the temporalis area ↓ Observe contraction of muscles
Motor: o Forehead wrinkling o Eyelid closure o Mouth retraction o Whistling or puffing out cheeks o Wrinkling of skin over the neck o Labial articulations
CN VII: FACIAL NERVE