Cranial Nerves Flashcards
(22 cards)
How many cranial nerves are there?
12 pairs
What are the 12 cranial nerves, which ones are sensory, motor or both?
I - Olfactory (Sensory)
II - Optic (Sensory)
III - Oculomotor (Motor)
IV - Trochlear (Motor)
V - Trigeminal (Both)
VI - Abducens nerve (Motor)
VII - Facial nerve (Both)
VIII - Vestibulocochlear (Sensory)
IX - Glossphangeal (Both)
X - Vagus (Both)
XI - Accessory (Motor)
XII - Hypoglossal (Motor)
What is the function of the olfactory nerve?
To transmit smell
What is the function of cranial nerves II and III, how are they linked?
II - Optic, senses eye input
III - Occularmotor, performs eye constriction/dilation
CN III also innervates eye muscles
What is the function of CN IV?
Trochlear nerve is responsible for looking down, moving eyes towards and away from nose
What is the function of CN V?
Trigeminal nerve, providing sensations in your eyes, most of your face and inside your mouth. It also allows you to chew food.
What is the function of CN VI?
Abducens nerve, moves your eyes from left to right
What is the function of CN VII?
Facial nerve, controls several facial muscles and taste in a part of the tongue
What is the function of CN VIII?
Vestibular cochlear nerve, provides sense of hearing and balance
What is the function of CN IX?
Glossopharangeal, providing taste sensations to part of your tongue and controlling muscles for swallowing. It also has parasympathetic nerve fibers that play a role in blood pressure regulation and saliva (spit) production. - Works with the vagus nerve to innovate the gag reflex
What is the function of CN X?
Vagus nerve, regulating several automatic bodily processes, including your digestion, blood pressure, heart rate, breathing, mood, saliva production and more. It’s the main nerve of your parasympathetic nervous system. Works with CN IX to innovate gag reflex
What is the function of CN XI?
Accessory nerve, controls shoulder and neck movement by innervating the sternocleidomastoid and trapezius muscles
What is the function of CN XII?
Hypoglossal nerve, controls tongue movement (speaking, eating, swallowing)
What are the 3 branches CN V?
V Trigeminal nerve branches into 3:
V1 - Opthalamic
V2 - Maxillary
V3 - Mandibular
How do you assess cranial nerve I?
Ask the patient if they have noticed any changes in their smell
How do you assess cranial nerves II, III, IV and VI?
Assess pupil size, shape and symmetry.
Assess visual acuity with a Snellen chart
Assess pupillary reflexes
- Direct
- Consensual
- Relative afferent pupillary defect (Swinging light test)
- Accommodation reflex
Assess colour vision
Assess visual neglect/attention
Assess visual field and blind spot
Assess eyelids
Assess eye movement (H test)
Assess for strabismus (Light reflex and Cover test)
How do you assess cranial nerve V?
Assess sensory component (Forehead, cheek, lower jaw)
Assess motor component (Eye blinking response and muscles of mastication/jaw jerk reflex)
How do you assess CNVII?
Ask for any changes in taste
Ask for any changes in hearing
Inspect for asymmetry
Assess facial movements (Eyebrow raise, cheek puff, eye scrunch against resistance, grin, pursed lips)
How do you assess CN VIII?
Gross hearing assessment
Rinne’s and Weber’s test
Turning marching test
Head thrust test
How do you assess cranial nerves IX and X?
Inspect the mouth, soft palate and uvula
Assess palate and uvula movement on vocalisation (Ahhhhh)
Assess cough and swallow
Gag reflex (this should only be performed if absolutely necessary)
How do you assess cranial nerve XI?
Inspect for evidence of muscle wastage of sternocleidomastoid and trapezius muscles
Assess shoulder raise against resistance and head turning against resistance
How do you assess cranial nerve XII?
Inspect for tongue wasting and fasciculations
Inspect for asymmetrical tongue protrusion
Assess tongue strength (against cheek)
