CN IX - XII Flashcards
CN IX: glossopharyngeal nerve MOTOR fx
stylopharyngeus muscle
-elevates pharynx during swallowing and speaking
Fibers arise form NUCLEUS AMBIGUUS in medulla
CN IX: glossopharyngeal nerve PARASYMPATHETIC fx
Parotid gland - largest salivary gland
Preganglionic arise from inferior salivatory nucleus in pons—>travel w/ tympanic n and lesser petrosal nerve —>synapse in octic ganglion providing postganglionics to parotid glands
CN IX: glossopharyngeal nerve SENSORY fx (touch pain temp)
Touch pain and temp:
Posterior 1/3 of tongue, upper pharynx and soft palate
Middle ear
Small region of skin near external auditory meatus
Primary sensory neurons to superior and inferior glossopharyngeal ganglion
Synapse in spinal trigeminal nucleus and ascends to PSC
CN IX exits
As several rootlets along upper and lateral medulla - just below pontomedullary junction and CNIII
Travels through subarachnoid space to exit at jugular foramen
CN IX: glossopharyngeal nerve SENSORY fx (taste)
Posterior 1/3 of tongue
Ascends to roster all nucleus solitaries in medulla
Ascends to taste area of cortex
CN IX: glossopharyngeal nerve SENSORY fx (carotid body)
Chemoreceptors and baroreceptors
Ascend to caudal nucleus solitaries in medulla
CN X: vagus MOTOR fx
Pharyngeal and upper esophageal muscles (swallowing)
Laryngeal muscles (speaking)
Motor fibers arise from nucleus ambiguus in medulla
Unilateral lesion of CN x
Difficulty swallowing and hoarseness
CN X: pharyngeal muscles and lesion
Soft palate elevation
W/ lesion - asymmetric elevation
(soft palate lower on side of lesion - uvula will deviate toward normal side)
NC X: parasympathetic
Heart, lungs, digestive tract
Largest part of CN X
Preganglionic arise in dorsal nucleus of CN X in medulla
Synapse in terminal ganglia w/in or near target organs
CN X sensory touch, pain, temp
Lower pharynx
Larynx
Meninges (dura of post fossa)
Small region of skin near external auditory meatus
Primary sensory neurons ascend to inferior vagal and superior vagal ganglion
Synapse in spinal trigeminal nucleus and ascend to PSC
CN X sensory - taste
Epiglottis and posterior pharynx
Ascends in upper nucleus solitaries in medulla
Ascends to taste area of cortex
CN X sensory aortic arch
Conveys input from aortic arch and thoracoabdominal viscera
-chemo and baro- receptors
Ascends to lower nucleus solitarius in medulla
CN XI motor fx
SCM - turns head to opposite side
UT - elevates shoulder
Spinal accessory nuclues sends odor axons
out of the gray matter of spinal cord which exit between the ventral and dorsal roots of the upper five segments of cervical spinal cord
Ascends through foramen magnum to the intracranial cavity
Descends through jugular foramen
CN XI lesions
SCM: weakness turning head toward opposite the lesion
UT: ipsilateral weakness of shoulder shrug
CN XI UMN lesion
SCM: descends to ipsilateral CN XI nuclues so weakness turning head to opposite side
UT: descend to contralteral CN XI nucleus weakness of opposite shoulder shrug
CN XII hypoglossal
Motor
Intrinsic and extrinsic muscles of tongue
Rootlets exit ventral medulla b/n pyramid and olive to travel through hypoglossal foramen
Hypoglossal nucleus
Midline on the floor of 4th ventricle in medulla
CN XII UMN lesion
From tongue area of PCM travel w/ corticobulbar tract to synapse on contralateral CN XII nuclei
Ipsilateral lesion of PMC or UMN of CB tract will cause contralateral tongue weakness
CN XII LMN lesion
Ipsilateral lesion to CN XII nucleus or nerve fibers will cause ipsilateral tongue weakness
Tongue will deviate toward weak side (side of lesion)
Dysarthria
Abnormal articulation of speech
• Motor articulatory disorder
• Can range from mild to unintelligible speech
• Can occur with dysfunction of muscles of articulation (jaw,
lips, pharynx, and tongue), NM junction, or peripheral or central portions of CN V, VII, IX, X, or XII
• Can have many other causes: dysfunction of PMC face area,
cerebellum, basal ganglia, or descending corticobulbar fibers
Common causes of dysarthria
CVA, MS, ALS, MG, ETOH, any other
muscular disorders
Dysphasia
Impaired swallowing
• Can lead to aspiration of food, choking, and esophageal
reflux can lead to aspiration of gastric secretions
• Caused by esophageal strictures, neoplasms, local lesions, or
neural or neuromechanical basis
• Can occur with dysfunction of CN V, VII, IX, X, or XII
• Can have the same cause(s) as dysarthria, and they can
occur together
Aspiration pneumonia
Caused by impaired swallowing function
• Difficult to treat
• Common cause of death
Gag reflex
Protective reflex preventing entry of foreign objects into alimentary and respiratory passageways
CN IX (sensory component) and CN X (motor component)
Touch posterior pharynx (or soft palate) with cotton-tipped swab, and pharyngeal muscles contract
PSEUDOBULBAR AFFECT (PBA)
Uncontrollable bouts of laughter or crying without any appropriate emotional reasons
• Brainstem nuclei involved in laughing and crying include
CN VII, IX, X, and XII
Lesions of corticobulbar pathways or brainstem
Can produce PBA
Common cause of PBA
CVA MS ALD AD TBI Tumors Etc
