Chapter 20 Cranial Nerves Flashcards
CN I
Olfactory
CN II
Optic
CN III
Oculomotor
CN IV
Trochlear
CN V
Trigeminal
CN VI
Abducens
CN VII
Facial
CN VIII
Vestibulocochlear
CN IX
Glossopharyngeal
CN X
Vagus
CN XI
Accessory
CN XII
Hypoglossal
Cranial Nerves have 4 functions
- supply motor innervation to muscles of the face, eyes, tongue, jaw, and 2 superficial neck muscles
- transmit somatosensory information from the skin and muscles of the face and the temporomandibular joint
- Transmit special sensory information related to visual, auditory, vestibular, taste, olfactory, and visceral senses
- provide parasympathetic regulation of pupil size, curvature of eye lens, heart rate, blood pressure, breathing, and digestion
Olfactory Nerve Lesions
result in inability to detect smells
Trigeminal Nerve Lesions
results in anesthesia of the area supplied by the ophthalmic, maxillary, or mandibular branch
Trigeminal neuralgia
dysfunction of the trigeminal nerve that produces severe, sharp, stabbing pain
pain triggered by eating, talking, touching
facial nerve lesions
causes paralysis or paresis of the ipsilateral muscles of facial expression
lesion causes one side of the face to droop
Bell’s palsy
if a lesion involves the facial nerve and the cause is unknown
diagnosis of exclusion
Identifiable causes of facial nerve palsy include
trauma
lyme
MS
cyst in the middle ear
tumor
Ramsay Hunt Syndrome
Ramsay Hunt Syndrome
facial and vestibulocochlear nerves are affected
caused by varicella-shingles
consists of acute facial paralysis, ear pain, and blisters on the external ear
facial muscle synkinesis
abnormal reinnervation of facial muscles causes synkinesis-involuntary movements that accompany voluntary movements
unilateral corticobrainstem lesion
interrupts voluntary control of contralateral facial muscles only on the lower half of the face
conductive deafness
occurs when transmission of vibrations is prevented in the outer or middle ear
causes: wax in outer ear canal, otitis media
sensorineural deafness
due to damage to receptor cells or the cochlear nerve
less common
causes: ototoxic drugs, Meniere’s disease, acoustic neuroma
tinnitus
infrequent, mild, high-pitched sounds lasting for seconds to minutes
glossopharyngeal lesion
interrupts the afferent limb of both the gag reflex and the swallowing reflex
vagus nerve lesion
results in difficulty speaking and swallowing, poor digestion, asymmetric elevation of the palate, hoarseness, and loss of the gag and swallowing reflex
accessory nerve lesion
causes flaccid paralysis of the ipsilateral sternocleidomastoid and trapezius muscles
hypoglossal nerve
causes atrophy of the ipsilateral tongue
dysphagia
difficulty swallowing
dysarthria
poor control of speech muscles
motor production of sound is affected
