Motor Speech: Cranial Nerves

hypoglossal nerve function

CN XII innervates all of the intrinsic and extrinsic muscles of the tongue except the palatoglossus (CN X). It is crucial for lingual articulatory movements as well as chewing and swallowing

vagus Nerve pathway

Cell bodies of the vagus nerve CN X that are relevant to speech originate in the nucleus ambiguus. Cell bodies of relevant sensory fibers originate in the inferior ganglion located in or near the jugular foramen ---Central processes of the sensory fibers terminate in the nucleus of the tractus solitarius in the brainstem CN X exits the skull through the jugular foramen along with CN IX and XI and then divides into the pharyngeal branch which enters the pharynx ---superior laryngeal branch ---recurrent laryngeal branch

CN VII

Facial Nerve

CN I

Olfactory

hypoglossal nerve

Provides the motor innervation for all the intrinsic muscles of the tongue and most of the extrinsic muscles Supplies the muscles of the tongue and muscles surrounding the hyoid bone and contribute to swallowing and speech

Cranial nerves sensory/motor distribution of the cranial nerves

S = Sensory M = Motor B = Both *S*ome *S*ay *M*arry *M*oney, *B*ut *M*y *B*rother *S*ays *B*ig *B*rains *M*atter *M*ost

Superior laryngeal branch pathway

enters the pharynx and larynx

CN XI

spinal accessory nerve

Cranial Nerve names mnemonic

*O*n *O*ld *O*lympus' *T*owering *T*ops *A* *F*air *A*rmed *G*oddess *V*iewed *S*ome *H*ops

speech characteristics of vagus nerve: bilateral pharyngeal branch lesions

*hypernasality* can be marked to severe, *audible nasal emission* may be apparent and *pressure consonants can be noticeably imprecise* because of the inability to impound intraoral pressure. *Loudness may be mildly reduced* because of damping effects of the nasal cavity and phrase length may be reduced because of nasal air wastage. *Facial grimacing* may develop in an effort to valve the airstream at the nares

checking function of sensory division of facial nerve

-A cotton tip applicator dipped in a solution that is sweet, salty, sour or bitter -Apply to one side then the other side of the extended tongue

speech characteristics of vagus nerve: unilateral Lesions of only the recurrent laryngeal nerve

-Breathy-hoarse vocal quality -Decreased loudness -Diplophonia (sometimes) -Pitch breaks

checking function of motor division of facial nerve

-Have the patient wrinkle forehead -Close eyes tight -Show their teeth -Purse lips or blow a kiss (orbicularis oris)

speech characteristics of vagus nerve: bilateral Lesions of only the recurrent laryngeal nerve

-Inhalatory stridor -The voice may be relatively unaffected because the folds are adducted close to the midline -Airway compromise can be a serious problem

speech characteristics of vagus nerve: unilateral Lesions of only the superior laryngeal nerve

-Mild breathiness or hoarseness and mildly reduced ability to alter pitch may be present -Loudness may be normal or mildly reduced -Difficulty altering pitch may reduce the ability to sing

speech characteristics of vagus nerve: bilateral Lesions of only the superior laryngeal nerve

-Mild to moderate breathiness and hoarseness -Decreased loudness -Markedly reduced ability to alter pitch

Olfactory nerve

-Not tested much unless a frontal lobe tumor is suspected -May be damaged in patients with closed head injuries, nasal obstruction, viral infections and can be abnormal in Parkinson's disease, Alzheimer's and Multiple Sclerosis -Test by asking if patients can smell, vanilla or cinnamon in each nostril

auditory nerve

-Sensory Cranial Nerve -Originates in the inner ear -Vestibular branch carries impulses for balance -Cochlear branch carries impulses for hearing

cranial nerves function

-They receive motor execution signals from both the right and left motor cortices to activate the muscles for speech production -They also provide sensory feedback by way of the indirect motor system to the premotor cortex for movement modification -CNs receive impulses from the cortex through the corticobulbar tract

checking function of Facial nerve

-look for asymmetry of facial shape. Smile, puff out their cheeks, clench their eyes tight, wrinkle their brow -check taste

Abducens Nerve

-motor cranial nerve -responsible for eyeball movement

cranial nerves: midbrain level

1-4

cranial nerves: pons level

5-8

cranial nerves: medulla level

9-12

CN VI

Abducens

non-speech characteristics of facial nerve lesions

At rest, the affected side sags and is hypotonic The forehead may be unwrinkled, the eyebrow drooped, the eye is opened and unblinking Drooling on the affected side may occur The nasolabial fold is often flattened and the nasal ala may be immobile during respiration During smiling the face retracts more toward the intact side Food may squirrel between the teeth and cheek on the weak side because of buccinator weakness The patient may bite the cheek or lip wen chewing or speaking and may have difficulty keeping food in the mouth With milder weakness - asymmetry may be apparent only with use as in voluntary retraction, pursing and cheek puffing With significant weakness - reduced or absent movement is apparent during voluntary emotional and reflexive activities Fasciculations and atrophy may be apparent on the affected side Abnormal movements of the face sometimes occur with CN VII lesions They are noteworthy because the are unexpected in the context of final common pathway (FCP) disease and may be confused with hyperkinesias of central nervous system (CNS) origin Synkinesis Hemifacial spasm Facial Myokymia

CN VIII

Auditory nerve

speech characteristics of vagus nerve: unilateral lesions below pharyngeal branch but including superior and recurrent laryngeal branches

Breathiness or aphonia, hoarseness, reduced loudness, diplophonia, reduced pitch and pitch breaks Rapid vocal flutter may be present during vowel prolongation Phrases may be short because of air wastage through the incompletely adducted glottis during phonation Speaking on inhalation is sometimes spontaneously adopted as a compensatory strategy Stridor or audible inhalation may be evident at inhalatory phrase boundaries ---Said characteristics can be exacerbated with bilateral paralysis

non-speech characteristics of glossopharyngeal nerve lesion

CN IX is assessed clinically by examining the gag reflex ---Asymmetry in the ease with which the reflex is elicited A reduced gag reflex may implicate the sensory or motor components of the reflex ---Sensory component - if the patient reports decreased sensation in the area CN IX may be implicated in dysphagia with lesions to it presumably affect pharyngeal elevation during the pharyngeal stage Some patients with CN IX lesions develop brief attacks of severe pain that begin in the throat and radiate down the neck to the back of the lower jaw. Pain can be triggered by swallowing or tongue protrusion ---Said condition is known as glossopharyngeal neuralgia

etiologies and localization of glossopharyngeal lesions

Cranial nerve IX is rarely damaged in isolation (at the least, CN X is involved) It is susceptible to the same pathologic influences that can affect other cranial nerves in the lower brainstem

cranial nerves

Cranial nerves are LMNs that originate in the cranial nerve nuclei (various levels of the brainstem) Some cranial nerves are motor only, some are sensory only and some are motor and sensory The cranial nerves innervate the muscles of the jaw, face (including lips), pharynx, larynx, soft palate, tongue and neck Some of these nerves bring information from the sense organs to the brain; other cranial nerves control muscles; other cranial nerves are connected to glands or internal organs such as the heart and lungs. If the complex interaction of the UMN neurotransmitters reach a certain excitatory threshold they will transmit a motor impulse to the cranial nerve, which in turn transmits a neural impulse to the muscle tissue it innervates

Trigeminal nerve Lesions

Damage to the trigeminal nerve CNV is usually associated with the involvement of other cranial nerves ----It is rarely the only cranial nerve involved in flaccid dysarthrias Etiologies most often include aneurysm, infection, arteriovenous malformation, tumors in the middle fossa or cerebellopontine angle and surgical trauma (posterior fossa, acoustic neuroma, temporomandibular joint) or non surgical trauma to the skill or anywhere along the nerve's course to muscle Peripheral branches of the nerve are most often damaged in isolation by tumors or fractures of the facial bones or skull Disease of the neuromuscular junction can cause jaw weakness, as can disease affecting the jaw muscles themselves (myopathies) The effects of CNV lesions on speech are most apparent during reading, conversation and alternate motion rates (AMRs) ---"p^" may be greater for imprecision or slowness than for "t^" or "k^"

Cranial Nerve IX

Glossopharyngeal Nerve

etiologies and localizations of hypoglossal nerve lesions

Hypoglossal nerve lesions can be intramedullary, extramedullary and extracranial They can be caused by any condition that can affect the lower cranial nerves and often involve other cranial nerves (IX, X and XI) Lesions can be isolated to the hypoglossal nerve itself and are usually caused by: ---Infection, basilar skull, neck, salivary gland or base of tongue tumors, trauma, surgery, carotid and vertebral artery aneurysms and radiation

Glossopharyngeal nerve

Innervates the stylopharyngeus muscle which assists in the elevation of the pharynx and larynx Plays a role in resonance and phonation by shaping the pharynx Makes a contribution to the gag reflex which is an important component of the act of swallowing --not necessary for normal swallow, but absent gag should send up a red flag It does not innervate an isolated function so it is tested with CN X- Vagus Nerve

The most important relationships between CN X lesion loci and impairment of muscle function include

Intramedullary, extramedullary and extracranial lesions above the separation of the pharyngeal, superior laryngeal and recurrent laryngeal branches affect all muscles supplied by the nerve below the level of the lesion. Therefore pharyngeal and palatal muscles supplied by the pharyngeal branch, the cricothyroid muscle supplied by the superior laryngeal branch and the remaining intrinsic laryngeal muscles supplied by the recurrent laryngeal branch are weak or paralyzed on the side of the lesion Lesions below the pharyngeal branch, but still high enough in the neck to affect the superior and recurrent branches, spare the upper pharynx and velopharyngeal mechanism but cause paralysis or weakness to the cricothyroid and other intrinsic muscles on the side of the lesion Lesions of the superior laryngeal branch but not the recurrent laryngeal or pharyngeal branches affect the cricothyroid but not the velopharyngeal mechanism or the remaining intrinsic laryngeal muscles. Lesions affecting only the recurrent laryngeal nerve cause weakness or paralysis of the intrinsic laryngeal muscles on the side of the lesion except the cricothyroid

testing the nerves that innervate the muscles of articulation

Is the patient's speech hoarse, slurred, quiet, breathy, nasal, low or high pitched? Abnormal articulation of speech can occur in lesions involving the muscles of articulation, the neuromuscular junction, or the peripheral or central portions of CNs V, VII, IX and XII Speech production can be abnormal as a result of lesions in the motor cortex, cerebellum, basal ganglia or descending pathways to the brainstem

etiologies and localizations of the spinal accessory nerve

Lesions of the spinal portion of CN XI reduce shoulder elevation on the side of the lesion and weaken head turning to the side opposite the lesion The usually do not affect speech If bilateral weakness causes significant shoulder weakness and head drooping then respiration, phonation and resonance may be indirectly and mildly affected by the postural distortion

CN III

Oculomotor

Extracranial lesions affecting CN X can be caused by

Myasthenia gravis, tumors (in the neck, lung or thorax), aneurysms in the aortic arch or internal carotid or subclavian artery, aortic or internal carotid artery dissection, endotracheal intubation, pulmonary or mediastinal tuberculosis, and viruses (i.e., herpes simplex virus, influenza)

CN II

Optic Nerve

Cranial nerves IX andX are tested together

Palatal Elevation and Gag Reflex Does the palate elevate symmetrically when the patient says, "Ah"? Does the patient gag when the posterior pharynx is brushed? Palate elevation and the gag reflex are impaired in lesions involving CN IX and CNX, the neuromuscular junction, or the pharyngeal muscles

speech characteristics of facial nerve lesions

Speech tasks that are most revealing of CN VII lesions are conversational speech, reading, speech alternate motion rates (AMRs) and stress testing Unilateral facial nerve paralysis on speech can be more visible than audible. ---There may be mild distortion of bilabial and labiodental consonants and less frequently anterior lingual fricatives and affricates ---There is usually no perceptible effect on vowels Bilateral facial weakness can lead to distortions or complete inability to produce certain consonants ---/p/, /b/, /m/, /w/, /hw/, /f/, and /v/ ---If lip rounding and spreading are markedly reduced - vowels may be distorted

spinal accessory nerve

Spinal accessory nerve's major function is to help turn, tilt and thrust the head forward Spinal accessory nerve supplies innervation for the trapezius and sternocleidomastoid muscles Related to posture for speech and feeding

testing the hypoglossal nerve function

Stick out tongue and move it from side to side Strength can be tested by having the patient push the tongue against a tongue blade p^t^k^ Note any atrophy or fasciculations (spontaneous quivering movements caused by firing of muscle motor units) of the tongue while it is resting on the floor of the mouth Ask the patient to stick their tongue straight out and note whether it curves to one side or the other Ask the patient to move their tongue from side to side and push it forcefully against the inside of each cheek Fasciculations and atrophy are signs of lower motor neuron lesions Unilateral tongue weakness causes the tongue to deviate toward the weak side

spinal accessory nerve pathway

The cranial portion of the accessory nerve CN XI arises from the nucleus ambiguus, emerges from the side of the medulla and exits the skull through the jugular foramen along with CN IX and X. It intermingles with fibers of CN X to help innervate the uvula, levator veli palatini and intrinsic laryngeal muscles The spinal portion arises from the first five to six cervical segments of the spinal cord, ascends and enters the posterior fossa through the foramen magnum and then leaves the skull with fibers of CN IX and X and the cranial portion of the nerve XI where it innervates the sternocleidomastoid and trapezius muscles

etiologies and localizations of vagus nerve lesion

The degree of weakness, positioning of paralyzed vocal folds and degree and type of voice or resonance abnormality depends on lesion localization along the course of the nerve and whether the lesion is unilateral or bilateral ---Vagus nerve lesions can be intramedullary, extramedullary or extracranial Careful consideration of signs and symptoms stemming from CN X lesions can often distinguish among lesions that are ---Intramedullary, extramedullary or above the pharyngeal branch ---Below the pharyngeal branch but above the superior and recurrent laryngeal branches ---Below the superior laryngeal branch

speech characteristics of vagus nerve lesions

The effects of CN X lesions cross several aspects of speech production including: --Phonation, resonance, articulation and prosody ------The effects on resonance and phonation are the most pronounced

etiologies and localization of facial Nerve lesions

The facial nerve CN VII can be damaged in isolation or along with other cranial nerves Pathology in the brainstem and posterior fossa can cause VII nerve damage, but a lesion anywhere along the nerve may affect its functions for speech Infectious causes of facial paralysis are inclusive of but not limited to: ---(VIRUSES OR TUMORS MOSTLY) Herpes zoster, mononucleosis, otitis media, meningitis, Lyme disease, syphilis, sarcoidosis, Guillain-Barré syndrome, and inflammatory polyradiculoneuropathy Common neoplastic causes include: ---Acoustic neuroma, parotid tumor, cerebellopontine angle meningitoma, tumor of the facial nerve and leptomeningeal carcinomatosis

facial nerve pathway

The facial nerve CN VII has both motor and sensory functions ---Only its motor component has a clear role in speech Motor fibers originate in the facial nucleus in the lower third of the pons and exit the cranial cavity, along with fibers of CN VIII, through the internal auditory meatus They pass through the facial canal and exit at the stylomastoid foramen below the ear, pass through the parotid gland and innervate the muscles of facial expression Facial muscles crucial for speech are those that move the lips and firm the cheeks to permit impounding of intraoral air pressure for bilabial and labiodental sounds

Facial Nerve

The facial nerve has two major branches: ---One for the muscles of the lower face ---One for the muscles of the upper face The facial nerve that serves the muscles of the lower face receives unilateral innervation from the opposite (contralateral) side of the brain The facial nerve that serves the muscles of the upper part of the face receives bilateral innervation from the right and left corticobulbar tracts The upper motor neurons for the upper face project to the facial nuclei bilaterally. Therefore, upper motor neuron lesions, such as a stroke, cause contralateral face weakness sparing the forehead, while lower motor neuron lesions, such a s a facial nerve injury, typically cause weakness involving the whole ipsilateral face

hypoglossal nerve pathway

The hypoglossal nerve CN XII originates in the medulla. Its fibers exit the brainstem as a number of rootlets that converge and pass through the hypoglossal foramen just lateral to the foramen magnum. The nerve travels medial to cranial nerves IX, X and XI in the vicinity of the common carotid artery and the internal jugular vein and passes above the hyoid bone to reach the intrinsic and extrinsic muscles of the tongue

Vagus nerve function

The internal laryngeal nerve, a component of the superior laryngeal nerve transmits sensation from mucous membranes of portions of: The larynx, epiglottis, base of tongue and aryepiglottic folds The external laryngeal nerve the motor component of the superior laryngeal nerve supplies the inferior pharyngeal constrictors and the cricothyroid muscles Its innervation of the cricothyroid muscle is important because cricothyroid contraction lengthens the vocal folds for pitch adjustments

speech characteristics of hypoglossal nerve lesions

The overriding speech characteristic in both unilateral and bilateral CN XII lesions is the imprecise articulation of lingual phonemes Isolated unilateral CN XII lesions are sometimes compensated for to a degree that allows perceptually normal speech ---Articulatory distortions are generally mild and do not affect intelligibility Bilateral lingual weakness affects sounds requiring elevation of the tip or back of the tongue ---When weakness is mild, anterior lingual consonant distortion is often detected more than velar distortions because of the greater number and more frequent occurrence of the anterior lingual consonants ---When weakness is more pronounced, velars can be particularly devastated, due to more tongue mass need to move in order to produce them Resonance differences are occasionally associated with bilateral lingual weakness and are sometimes noted as hypernasality or hyponasality ---Believed to be because the weak tongue falls back into the pharynx altering its shape and thus altering the characteristics of resonance The most useful tasks for assessing lingual movement for speech are connected speech as this places heavy demands on rapid, variable movements and may be most useful in identifying lingual distortions ---/p^/ should be OK ---/t^/ and /k^/ may be imprecise and slow

non-speech characteristics of vagus nerve: bilateral pharyngeal branch lesions

The palate hangs low in the pharynx at rest and moves minimally or not at all during phonation The gag reflex may be difficult to elicit or absent (although may be normal in some individuals) Nasal regurgitation may occur during swallowing

non-speech characteristics of vagus nerve lesions

The paralytic appearance of the vocal folds and larynx at rest in response to superior or recurrent laryngeal branch lesions can include: ---Shortening of the affected vocal fold and shift of the epiglottis and anterior larynx toward the intact side in unilateral lesions ---Shortening and bowing of the affected vocal fold or folds ---Paramedian position of the paralyzed vocal fold or folds ---Abducted position of the parlayed vocal fold or folds In unilateral vocal fold paralysis, dysphagia may be present in more than half of patients. The cough can be weak and there may be airway compromise In bilateral paralysis, airway compromise and inhalatory stridor often occur because abductor paralysis prevents widening of the glottis during inhalation. The resulting respiratory distress may require tracheotomy. Dysphagia and other signs of weakness are generally worse with bilateral than unilateral vocal fold lesions

pharyngeal branch of vagus nerve function

The pharyngeal branch supplies: ---the muscles of the pharynx except the stylopharyngeus (CN IX) ---the muscles of the soft palate except the tensor veli palatini (mandibular branch of CN V) ---the palatoglossus muscle It is responsible for pharyngeal constriction and palatal elevation and retraction during both speech and swallowing

recurrent laryngeal branch of vagus nerve function

The recurrent laryngeal branch of the nerve innervates all of the intrinsic laryngeal muscles except the cricothyroid The sensory fibers carry general sensation from the vocal folds and the larynx below them

speech characteristics of glossopharyngeal nerve lesions

The role of CN IX in speech cannot be assessed directly ---The nerve probably influences resonance and perhaps phonatory functions as lesions will affect pharyngeal elevation As CN IX lesions are usually associated with CN X lesions and because CN X has a crucial and relatively clearly defined role in speech, CN IX's importance in the assessment of dysarthria is not as clearly defined for practical purposes

non-speech characteristics of vagus nerve: unilateral pharyngeal branch lesions

The soft palate hangs lower on the side of the lesion and pulls toward the non-paralyzed side on phonation The gag reflex may be diminished on the weak side

non-speech characteristics of unilateral hypoglossal lesions

The tongue may be atrophic and shrunken on the weak side Fasciculations may be apparent The tongue deviates to the weak side on protrusion The ability to curl the tip of the tongue to the weak side inside the mouth is diminished as is the ability to push the tongue into the cheek against resistance

non-speech characteristics of bilateral hypoglossal lesions

The tongue may be atrophic bilaterally Fasciculations may be bilateral The tongue may protrude symmetrically but with limited or no range Lateralization and elevation may be impossible Saliva may accumulate in the mouth and food may squirrel in the cheeks and there may be drooling The patient may complain that the tongue feels "heavy", "thick" or "big" or that it does not move well for eating or speaking

CN X

Vagus Nerve

Trigeminal Nerve

The trigeminal nerve is both sensory and motor Facial sensation and muscles of mastication Testing --Palpate the masseter muscles as the patient bites down hard --Open mouth and resist the examiner's attempt to close the mouth --Jaw jerk or reflex Divides the three main branches of the: --Ophthalmic --Maxillary --Mandibular Mandibular branch of the CN V is important for speech because it innervates muscles that elevate and lower the jaw and the velum

Oculomotor, Trochlear, and Abducens Nerves

These 3 nerves control eye movement and pupil diameter Hold up a finger in front of our partner. Tell your partner to hold his/her head still and follow your finger, then move your finger up and down, right and left. Do your partner's eyes follow your finger?

Trigeminal nerve pathway (probably not on quiz)

Three main branches of the trigeminal nerve CN V arise in the trigeminal ganglion in the petrous bone of the middle cranial fossa Central connections form the trigeminal ganglion enter the lateral aspect of the pons and are distributed to various nuclei in the brainstem The peripheral distribution of the trigeminal nerve includes the sensory ophthalmic branch which exits the skull through the superior orbital fissure to innervate the upper face The secondary maxillary branch exits the skull through the foramen rotundum to supply the mid face The motor and sensory mandibular branch exits the skull through the foramen ovale to supply the jaw muscles, tensor tympani and tensor veli palatini

testing the spinal accessory nerve function

To test the strength of the muscles used in head movement, put your hands on the sides of your patient's head. Tell the patient to move his/her head from side to side. Apply only light pressure when the head is moved.

cranial nerves of speech production

Trigeminal (V) Facial (VII) Glossopharyngeal (IX) Vagus (X) Spinal Accessory (XI) Hypoglossal (XII)

CN V

Trigeminal Nerve

Trigeminal Nerve Function

Trigeminal functions for speech are mediated through the nerve's maxillary and mandibular branches Sensory contributions include tactile and proprioceptive information about the jaw, face, lip and tongue movements in relationship to stationary articulatory structures in the mouth (i.e., teeth, palate) Motor fibers drive jaw movements during speech

CN IV

Trochlear

Intramedullary and extramedullary lesions affecting CN X can be caused by

Tumor, infection, stroke, Arnold-Chiari malformation, Guillain-Barré syndrome, polio, motor neuron disease and other inflammatory or demyelinating diseases

nerves that innervate Muscles of articulation

V - trigeminal VII - facial IX - glossopharyngeal XII - hypoglossal

Vagus Nerve

Vagus means wanderer. It is a long nerve with many branches serving various parts of the body such as the: ---Larynx, intestines, heart and velum Three branches of the CNX have special importance to motor speech production: ---Pharyngeal nerve branch ---External superior laryngeal nerve branch ---Recurrent nerve branch These nerves have a more extensive distribution than any other cranial nerve as they pass down through the neck into the thorax and the abdomen

Optic Nerve

Visual Acuity (test with hand card) Color Vision (loss of color vision especially red is an important symptom of optic neuritis Visual Fields ( can be tested at the bedside by counting fingers in each quadrant --involves single side neglect (like left side neglect from right hemisphere impairment) Visual Extinction (to detect visual neglect) Instrumental Examination

Facial nerve lesions: ball's palsy

a relatively common condition, accounting for a majority of acute facial palsies Most frequent cause is due to latent herpes viruses, but autoimmune mediated inflammatory neuropathy and swelling of the nerve induced by exposure to cold or allergic factors are other possible causes It is characterized by isolated unilateral CN VII weakness Upper and lower facial muscles are affected Some patients also have decreased lacrimation, salivation and taste sensation as well as hyperacusis (possibly due to the involvement of the portion of the nerve that innervates the stapedius) A small percentage of patients may have other cranial neuropathies usually affecting the trigeminal, glossopharyngeal or hypoglossal nerves About 3/4 of patients recover normal facial function, but lasting weakness can occur

cranial nerves originate in the

brainstem at the CN nuclei

Non-speech characteristics of facial Nerve lesions: Hemifacial spasm

characterized by paroxysmal, rapid, irregular usual unilateral tonic spasm of the facial muscles It may be due to irritation of the nerve by a pulsating blood vessel in the area of the cerebellopontine angle or facial canal or it may be associated with tumor vascular abnormalities or multiple sclerosis

Non-speech characteristics of facial Nerve lesions: facial myokymia

characterized by rhythmic, undulating movements on an area of the face in which the surface of the skin moves like a "bag of worms" Such movements are more prolonged than fasciculations and reflect alternating brief contractions of adjacent motor units They are often benign but if widespread may be associated with multiple sclerosis, brainstem tumors, syringobulbia (neurological disorder characterized by a fluid-filled cavity (syrinx) within the spinal cord that extends to involve the brainstem (medulla), or demyelinating cranial neuropathies, or they may occur after head and neck radiation therapy

Trigeminal nerve Lesions: Trigeminal Neuralgia

characterized by sudden, brief periods of pain in one or more of the sensory divisions of the nerve It is often idiopathic, but many cases reflect compression or irritation of the trigeminal sensory roots Pain can be triggered by sensory input from facial or jaw movement, sometimes leading to restricted lip, face or jaw movements during speech to avoid triggering pain

CN XII

hypoglossal nerve

extracranial lesions

on vagus nerve damage the nerve after it exits the skull

extramedullary lesions

on vagus nerve damage the truck of the nerve as it leaves the body of the brainstem but while it is still within the cranial cavity (before it exits the jugular foramen)

intramedullary lesions

on vagus nerve damage to the nerve in the brainstem

afferent fibers of the glossopharyngeal nerve pathway and function

originate in the inferior ganglion in the jugular foramen and terminate in the nucleus of the tractus solitarius in the medulla --They carry sensation from the pharynx and posterior tongue and are important to the sensory component of the gag reflex

Recurrent laryngeal branch pathway

passes down to the upper chest where it loops around the subclavian artery on the right and around the aorta on the left before traveling back up the neck to enter the larynx

neuromuscular junction

point where the axons of the PMN make synaptic connections with muscle cells

motor fibers of glossopharyngeal nerve pathway and function

that are relevant to speech originate in the nucleus ambiguus within the reticular formation of the lateral medulla. The nerve roots emerge from the medulla and exit through the jugular foramen in the posterior fossa and eventually pass into the pharynx to innervate the stylopharyngeus muscle which elevates the pharynx during swallowing and speech

Non-speech characteristics of facial Nerve lesions: Synkinesis

the abnormal contraction of muscle adjacent to muscle that is contracting normally A normal reflexive or voluntary eye blink may cause simultaneous movement of lower facial muscles

Trigeminal Nerve Lesions: bilateral mandibular branch lesion

the jaw may hang open at rest. ---Patient may be unable to close the jaw or may move it slowly or with reduced range ---Patient may complain of chewing difficulty, drooling and the recognition that the jaw is difficult to close or move - can have a devastating effect on articulation ---The inability to elevate a bilaterally weak jaw can reduce precision or make it impossible to produce bilabial, labiodental, lingual-dental and lingual alveolar articulation as well as lip and tongue adjustments for many vowels, glides and liquids ---Speech rate can be slow, either as a direct effect of weakness or in compensation for weakness

Trigeminal Nerve Lesions: unilateral mandibular branch lesion

the jaw will deviate to the weak side when opened and the partly opened jaw may be pushed easily to the weaker side. ---Masseter or temporalis contraction felt on palpation when the patient bites down may be decreased on the weak side do not have a perceptible affect on speech

speech characteristics of vagus nerve: unilateral pharyngeal branch lesions

there may be little or no perceptible effect on resonance or only mild hypernasality and nasal emission during pressure consonant production