Cranial Nerves Flashcards
what are the cranial nerves in order?
I-olfactory II-optic III-oculomotor IV-trochlear V-trigeminal VI-abducens VII-facial VIII-vestibulocochlear IX-glossopharyngeal X-vagus XI-accessory XII-hypoglossal
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which cranial nerves have sensory only, motor only, or both?
I-olfactory: sensory II-optic: sensory III-oculomotor: motor IV-trochlear: motor V-trigeminal: both VI-abducens: motor VII-facial: both VIII-vestibulocochlear: sensory IX-glossopharyngeal: both X-vagus: both XI-accessory: motor XII-hypoglossal: motor
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what is the function of the olfactory nerve?
smells
a lesion in the olfactory nerve results in what?
dysosmia
what is the function of the optic nerve?
sees
a lesion in the optic nerve results in what?
visual field deficits (anopsia)
loss of sensory limb of light reflex with III (oculomotor)
*only nerve to be affected by multiple sclerosis
what is the function of the oculomotor nerve?
motor: to all eyeball muscles except lateral rectus and superior oblique; adduction (medial rectus) is the most important action; elevates upper eyelid (levator palpebrae superioris)
parasympathetic: constricts pupil (sphincter pupillae) and accomodates (ciliary muscle)
a lesion in the oculomotor nerve results in what?
diplopia with external strabismus, ptosis, dilated pupil, loss of motor limb of light reflex with II (optic nerve), loss of near response
what is the function of the trochlear nerve?
superior oblique: depresses and abducts eyeball
intorts eyeball
a lesion in the trochlear nerve results in what?
weakness looking down with eye adducted, difficulty reading, going down stairs, head tilt away from lesioned side
what are the three branches of the trigeminal nerve?
V1= ophthalmic V2= maxillary V3= mandibular
what is the function of V1?
SENSORY
general sensation of forehead, scalp, cornea, dorsum of nose, nasal cavity
what is the function of V2?
SENSORY
general sensation of palate, nasal cavity, maxillary face, maxillary teeth
what is the function of V3?
SENSORY AND MOTOR
general sensation of anterior 2/3 of tongue, mandibular face, mandibular teeth
muscles of mastication (temporalis, masseter, medial and lateral pterygoids). anterior belly of digastric, mylohyoid, tensor tympani, tensor palati
a lesion in V1 results in what?
loss of general sensation in skin of forehead/scalp, loss of sensory limb of blink reflex with VII
a lesion in V2 results in what?
loss of general sensation in skin over maxilla, maxillary teeth
a lesion in V3 results in what?
loss of general sensation in skin over mandible, mandibular teeth, tongue, weakness in chewing
jaw deviation on protrusion toward lesioned nerve
what is the function of the abducens nerve?
to lateral rectus: abducts eyeball
a lesion in abducens results in what?
diplopia with internal strabismus, pseudoptosis
what is the function of the facial nerve?
MOTOR AND SENSORY
to muscles of facial expression (orbicularis oculi and oris, platysma, buccinator) and to posterior belly of digastric, stylohyoid, stapedius
taste anterior 2/3 of tongue/soft palate, general sensation in skin behind ear
saliva (submandibular, sublingual glands), tears (lacrimal gland), mucus (nasal and palatine glands)
a lesion in the facial nerve results in what?
corner of mouth droop, can’t close eye, wrinkle forehead, loss of motor limb of blink reflex with trigeminal (V1), hyperacusis
altered taste from anterior 2/3 of tongue, pain behind ear
reduction in output of saliva, in secretions, and eyes dry and red
what is the function of the vestibulocochlear nerve?
hears, linear acceleration (gravity), angular acceleration (head turning)
a lesion in the vestibulocochlear nerve results in what?
sensorineural hearing loss, loss of balance, nystabmus (involuntary eye movements)
what is the function of the glossopharyngeal nerve?
MOTOR AND SENSORY
to only one muscle: stylopharyngeus
general sensation of oropharynx, carotid sinus, and carotid body, taste and general sensation of posterior 1/3 of tongue
saliva (parotid gland)
a lesion in the glossopharyngeal nerve results in what?
loss of sensory limb of gag reflex with X
reduction in output of saliva
what is the function of the vagus nerve?
MOTOR AND SENSORY
to muscles of palate except tensor palati
to muscles of pharynx except stylopharyngeus
to all muscles of larynx
senses larynx and laryngopharynx
to cardiac muscle and lung smooth muscle
to glands and smooth muscle in foregut and midgut
a lesion in the vagus nerve results in what?
nasal speech, nasal regurgitation, palate droop, tip of uvula deviates away from lesioned nerve, dysphagia, loss of motor limb of gag reflex with IX, hoarseness
loss of cough reflex
reduced peristalsis
what is the function of the accessory nerve?
turns chin to opposite side (SCM) and elevates and upwardly rotates scapula (trapezius)
a lesion in the accessory nerve results in what?
weakness turning chin to opposite side, shoulder droop, difficulty combing hair
what is the function of the hypoglossal nerve?
to all muscles that act on tongue except palatoglossus (vagus nerve): hyoglossus, styloglossus, genioglossus, intrinsics
a lesion in the hypoglossal nerve results in what?
tongue deviation on protrusion toward side of lesioned nerve
what is the function of the sympathetic nerves to the face, scalp, and orbit (cervical sympathetic trunk)?
elevates upper eyelid (superior tarsal muscle)
dilates pupil (dilator pupillae)
innervates sweat glands of face and scalp
a lesion in the sympathetic nerves to the face, scalp, and orbit (cervical sympathetic trunk)?
ptosis, constricted pupil (miosis), loss of sweating (anhydrosis)–>Horner’s syndrome
