Cranial Nerves (2) Flashcards
What is the function of CN 1?
Smell
What happens if there is a lesion to CN 1?
Inability to smell (anosmia)
How is CN 1 tested?
Patient identifies smell using one nostril while other is held closed
What is the function of CN 2?
Vision
What happens if there is a lesion to CN 2?
Vision loss
How is CN 2 tested?
Acuity test (eye chart)
Peripheral vision
What is the function of CN 3?
Motor for SR, IR, MR, and IO
Efferents for vestibulo-ocular reflex
PSNS- sphincter of pupil, ciliary muscle of lens, and efferent for pupillary and accommodation reflexes
What happens with a lesion to CN 3?
Unable to move eye up, down, and medial
Ptosis
Nystagmus
Pupil dilation
Blurred vision due to loss of accommodation
What is the function of CN 4?
Motor to SO
Efferents for vestibulo-ocular reflex
What happens if there is a lesion to CN 4?
Difficulty moving eye inferior and medial
Diplopia
What is the function of CN 5?
Sensory- Somatosensation from the face and TMJ (afferents for corneal reflex)
Motor- muscles of mastication
What happens if there is a lesion to CN 5?
Trigeminal neuralgia
Loss of tactile sensation in face
Weakness in biting
Jaw jerk reflex (UMN lesion)
What is testing for CN 5?
MMT for closing mouth (will decide towards weak side)
Palpate temporalis and masseter during AROM
What is the function of CN 6?
Motor to LR
Efferents for vestibulo-ocular reflex
What happens if there is a lesion to CN 6?
Eye deviates medially
Diplopia
What is the function of CN 7?
Sensory- taste anterior 2/3 of tongue
Motor- muscles of facial expression
PSNS- submandibular, sublingual, and lacrimal glands
What happens if there is a lesion to CN 7?
Loss of taste on anterior 2/3 of tongue
Facial palsy
Decreased salivation/tear production
How do you test for CN 7?
If it’s a UMN (corticobrainstem) problem you get contralateral paresis of lower face
If it’s a CN problem you get ipsilateral paralysis of entire face
(Raise eyebrows, close eyes, pucker lips, puff cheeks)
What is the function of CN 8?
Sensory- hearing and balance
What happens if there is a lesion to CN 8?
Loss of hearing and balance
Nausea
Vertigo
What is the function of CN 9?
Sensory- pharynx, larynx, middle ear, and taste on posterior 1/3 of tongue (afferent for gag reflex)
Motor- pharyngeal muscles
PSNS- parotid gland
Visceral afferents- carotid body and carotid sinus
What happens if there is a lesion to CN 9?
Loss of gag reflex
Difficulty swallowing
Decreased salivation
Decreased regulation of HR
What if the function of CN 10?
Sensory- pharynx, larynx, skin of external ear
Motor- muscles of pharynx and larynx
PSNS- efferents to smooth muscles and glands in pharynx and larynx
Visceral afferents- pharynx, larynx, thorax, and abdomen
What happens if there is a lesion to CN 10?
Difficulty swallowing
Uvula deviates away from side of dysfunction
What is the function of CN 11?
Motor to SCM and trap
What is the function of CN 12?
Motor to tongue muscles and throat muscles
What happens if there is a lesion to CN 12?
Tongue deviates toward side of lesion
How is CN 3 tested?
Pupillary light reflex (pupils constrict on both sides when a light is directed into one of them)
How do you test CN 4?
Bring pen towards face until vision is blurred
How do you test for CN 6?
H-test
How do you test CN 8?
Rub fingers together near ear and have patient point to side of sound being heard
How do you test CN 9, 10, and 12?
Stick tongue out and say ahhhh (looking for elevation of soft palate)
