Chapter 17 Flashcards
Cranial nerves
Serve four general sensory functions and motor functions
Regulate vision, audition, olfaction, gustation and speech
Can be sensory, motor or mixed nerves
Most cranial nerve nuclei are located in the ventricular floor of the brainstem
Bilateral
Paired
contralateral
cranial nerve mnemonic
On Old Olympus Towering Top a Fin and German Vended at Hops
12 cranial nerve names
Olfactory,Optic, Occulomotor, Trochlear, Trigeminal Abducens, Facial , Acoustic (VC), Glossopharyngeal, Vagus, Accessory, Hypoglossal
Olfactory Nerve
Sensory Age 60-65 begin to lose sense of smell Anosmia Hyperosmia Hyposmia Bilateral lesions have a drastic effect on sense of smell
Optic Nerve
Sensory
Selected visual field loss
Lesion of entire optic nerve would result in complete blindness
Oculomotor
Motor
TBI
Ptosis
strabismus
Trochlear
Motor
Weakness or paralysis of the superior oblique muscle
diplopia
Trigeminal
Mixed
Sensory
Principal sensory nerve for the head, face, orbit and oral cavity
Mediates sensations of pain temperature, and discriminative touch from face, head, oral and nasal cavities, teeth and anterior two thirds of the tongue, auditory meatus
Motor
Motor supplies the jaw muscles
Controls mastication
Trigeminal Branches
Sensory and motor together form the jaw jerk reflex Has three sensory branches ophthalmic, maxillary, mandibular
Ophthalmic Branch
Mediates the sensations of touch, pain and temperature from the ‘skin of the forehead Anterior scalp Eyeball Upper eyelid Cornea Anterior and lateral surface of the nose Frontal and nasal sinuses
Maxillary Branch
Sensation from
Temples Posterior portion of nose Upper cheeks Lower eyelids Upper lip Upper gum Soft and hard palate
Mandibular branch
Largest branch
Mediates sensation from the skin on the sides of the scalp
Lowe gums
The mouth
External auditory meatus
External surface of the tympanic membrane
Anterior two thirds of the tongue
Motor functions
Controls the muscles of mastication
Internal and external pterygoid, temporalis, and masseter also the mylohyoid, anterior belly of the digastric, tensor veli palatine and tensor tympani
Clinical Correlates of Trigemial Nerve
Sensory
Ipsilateral loss of sensation in the area of distribution of the nerve
Loss of sneezing and blinking reflex
Trigeminal neuralgia (usually ophthalmic or mandibular branch)
Motor
Flaccid paresis or paralysis of the ipsilateral muscles of mastication
Muscle atrophy
Abducens
Motor
Contributes to ocular movements
Medial strabismus
Facial Nerve
Mixed
Primarily a motor nerve for the muscles of facial expression
Strapedius muscle
Small sensory component for taste sensation from the anterior two thirds of the tongue and nasopharynx
facial nerve clinical coorelates
Pons
Paralysis of the ipsilateral facial muscles
Excessive gland secretions
Loss of taste from the anterior two thirds of the tongue
Fibers beyond stylomastoid
Paralysis of ipsilateral half of the facial muscles
Motor root
Taste sensation from anterior two thirds of the tongue
Excessive gland secretions
LMN or bilateral cortical lesion
Paralysis of all the upper and lower muscles in the face
Articulation deficits of labial and labiodental sounds
UMN or pseudobulbar palsy
Bilateral facial palsy
Profound impairments in motor speech
Preservation of emotional expression while facial muscles are paralyzed for voluntary control
Auditory
Vestibulocochlear
sensory
Mediates head position (equilibrium) in space
hearing
Vestibulocochlear nerve
A purely sensory nerve, it carries afferent messages associated with a sense of equilibrium from the vestibular apparatus and semicircular canals. It also carries impulses associated with hearing from the cochlea of the inner ear.
glossopharyngeal
Mixed
Mediates touch, pain, tension and temperature sensations from intraoral structures
Sensation from upper pharynx, tonsils, Eustachian tube, middle ear cavity, soft palate
Taste information from posterior third of the tongue
Contributes to swallowing
glossopharyngeal clinical coorelates
Lesion is rare
Partial paresis of the unilateral stylopharyngeal muscle
Impairing the ipsilateral pharyngeal elevation
Loss of gag reflex
Excessive oral secretion
Vagus Nerve
Mixed
Wanderer
More extensive distribution then any other cranial nerve
90% sensory 10% motor
Control of the muscles used for phonation and swallowing
Innervates cardiac muscles
Smooth muscles of the esophagus, stomach, intestines
Innervates muscles of the pharynx and larynx
Sensation of pain, touch, pressure from mucosa of the pharynx, epiglottis, trachea, bronchi, esophagus, and stomach
Regulates cardiovascular, respiratory and gastrointestinal functions
Accessory
Motor
Trapezius
Sternocleidomastoid
Clinical correlates
Ability to control head movements
Hypoglossal
Motor
Controls tongue movement
Innervates all ipsilateral intrinsic and most extrinsic tongue muscles except the palatoglossal
Hypoglossal Clincal Coorelates
Unilateral paralyzed ipsilateral half of tongue
Becomes flaccid and wrinkled and eventually atrophy
Dysarthria
Chewing difficulties
On protrusion, the tongue deviates to the side of the lesion
Bilateral
Severe difficulty in oral stage of swallowing eating and speaking
Significant articulation difficulties
Cranial nerve syndromes
Weber Millard Gubler Locked in syndrome Wallenberg Dejerine
Weber
Midbrain lesion Oculomotor nerve Contralateral hemiplegia Ipsilateral ocular paralysis Ptosis Pupil dilation Lateral deviation of the ipsilateral eye
Millard-Gubler
Lower pons lesion
Facial nerve Descending motor fibers Marked contralateral hemiplegia Ipsilateral facial paralysis Motor speech disorder
Locked In Syndrome
Bilateral pons lesion
Interrupts all the descending corticospinal fibers
Quadriplegia
Loss of all motor speech functions
Patient remains fully awake and can blink only
TBI
Wallenburg
Lateral medulla lesion
Loss of pain sensation from the ipsilateral face and contralateral side of the body
Limited motor and speech movements of the pharynx, larynx, and soft palate
Dejerine
Medial Medulla Lesion
Contralateral hemiplegia contralateral loss of proprioception and vibration
Ipsilateral lingual paralysis
