CSD 450 Neuro Exam 2

what is the pyramidal system?

motor system causing voluntary actions

the CNS is split into two systems…

the pyramidal system and extrapyramidal system

what is the function of the pyramidal system?

directly innervates motor neurons coming out of spinal cord or brainstem

what is the extrapyramidal system?

motor system causing involuntary actions

what is the function of the extrapyramidal system?

modulates and regulates involuntary motor movement

example: reflexes, posture, gastric motility

what is the difference between the pyramidal and the extrapyramidal system?

extra regulates involuntary, pyramidal regulates voluntary

what is the contralateral innervation pathway?

innervation on opposite side of origin

left side of brain controls right side of body

what is the ipsilateral innervation pathway?

innervation on same side of origin

what is the bilateral innervation pathway?

innervation originates from both sides of brain

ipsilateral and contralateral

most nerves that control the lips, face and tongue are _____________ innervated.

bilaterally

what is the corona radiata?

giant projection fibers (axons) that connect cortex to internal capsule

neural highway

what is the internal capsule?

projection fibers- tract of axons from corona radiata that converges into tube

goes through striations of the basal ganglia

corticobulbar tract runs within which projection fiber structures?

internal capsule and corona radiata

define somatotopic organization

point-for-point correspondence of area of body to specific point on CNS

primary motor cortex’s map called homunculus

define upper motor neuron system

motor neurons in the CNS that initiate and modulate motor movement

intention!

what is the function of the direct activation pathway of the UMN system?

influences consciously controlled, skilled voluntary movement

(pyramidal)

begins in the motor area of the frontal lobe in the cortex

what is the function of the indirect activation pathway of the UMN system?

mediates subconscious, automatic muscle activity (posture, muscle tone, supportive movement)

(extrapyramidal)

support DAP- keeps system ready to have voluntary movement

what tracts are associated with the DAP?

corticobulbar and corticospinal tracts

what tracts are associated with the IAP?

corticoreticular, corticorubral, reticulospinal tracts

where does the corticobulbar tract begin and end?

begins: cortex

ends: brainstem nuclei

where does the corticospinal tract begin and end?

begins: cortex

ends: spinal cord nuclei

what is the function of the corticobulbar tract?

articulation, phonation, resonance

what is the function of the corticospinal tract?

respiration

where does the corticoreticular tract begin and end?

begins: cortex

ends: reticular formation

where does the corticorubral begin and end?

begins: cortex

ends: red nucleus

where does the reticulospinal tracts begin and end?

begins: reticular system

ends: spinal cord

what is the function of the reticulospinal tract?

gross motor movements

what is the function of the corticorubral tract?

excite and inhibit muscles

what is the function of the corticoreticular tract?

life sustaining functions- blood pressure, respiration, muscle tone, posture, reflexes, relay station

what are the general unilateral symptoms of damage to DAP?

weakness, reduction of skilled motor movements, possible paralysis

what are the general bilateral symptoms of damage to DAP?

spastic dysarthria, bilateral weakness, complete loss of skilled movement

what are the general symptoms of damage to IAP?

deficits in posture, tone (spasticity), and reflexes (hyperreflexia)

what is the function of the reticular formation?

Life sustaining functions (blood pressure, respiration, sleep cycles), supports muscle tone, posture, reflexes, relay station

what is the final common pathway?

lower motor neuron system

what is the lower motor neuron system?

motor neurons that connect with upper motor neurons that activate skeletal/somatic muscles

starts in brainstem, ends in muscle

what can damage to the lower motor neurons cause?

weakness, paralysis, paresis, atrophy, twitches, fibrillation, flaccidity

name the cranial nerves

I: olfactory

II: optic

III: oculomotor

IV: trochlear

V: trigeminal

VI: abducens

VII: facial

VIII: vestibular

IX: glossopharyngeal

X: vagus

XI: accessory

XII: hypoglossal

what number is the olfactory cranial nerve?

I

what number is the optic cranial nerve?

II

what number is the oculomotor cranial nerve?

III

what number is the trochlear cranial nerve?

IV

what number is the trigeminal cranial nerve?

V

what number is the abducens cranial nerve?

VI

what number is the facial cranial nerve?

VII

what number is the vestibular cranial nerve?

VIII

what number is the glossopharyngeal cranial nerve?

IX

what number is the vagus cranial nerve?

X

what number is the accessory cranial nerve?

XI

what number is the hypoglossal cranial nerve?

XII

what is the function of the olfactory (I) nerve?

smell

what is the function of the optic (II) nerve?

vision

what is the function of the oculomotor (III) nerve?

muscles for eyeball, pupil, upper lid

what is the function of the trochlear (IV) nerve?

superior oblique muscle of eye

what is the function of the trigeminal (V) nerve?

chewing and sensation to face, teeth, anterior tongue

what is the function of the abducens (VI) nerve?

abduction of the eye

what is the function of the facial (VII) nerve?

innervate facial muscles, taste, salivary glands

what is the function of the vestibular (VIII) nerve?

equilibrium and hearing

what is the function of the glossopharyngeal (IX) nerve?

taste, swallowing, elevation of pharynx and larynx, parotid salivary gland, sensation to posterior tongue, upper larynx

what is the function of the vagus (X) nerve?

taste, swallowing, elevation of palate, phonation, parasympathetic outflow to visceral organs

what is the function of the accessory (XI) nerve?

turning of head and shrugging of shoulders

what is the function of the hypoglossal (XII) nerve?

movement of tongue

what type of nuclei does the trigeminal (V) cranial nerve have?

3 sensory nuclei, 1 motor nuclei

where does the trigeminal (V) nerve receive sensory information from?

forehead, eyes, nose, lips, maxilla, teeth, cheeks, palate, maxillary sinus, anterior 2/3 of tongue, mandible, teeth, part of external ear

what does the trigeminal (V) nerve innervate?

muscles of mastication and tensor tympani muscle

what is the innervation pattern of the trigeminal (V) nerve?

bilateral innervation from UMN system

what happens when the unilateral LMN of the trigeminal (V) nerve is damaged?

lateral jaw movement issues, muscle atrophy, flaccidity or paralysis

deviation of jaw to side of lesion, inability to force jaw toward side opposite of lesion

what are the speech subsystems?

phonatory, resonance, articulatory and prosody

what happens when the unilateral and bilateral UMN of the trigeminal (V) nerve are damaged?

bilateral UMN: slow, weak and tight chewing and biting, restricted opening/closing of jaw, spasticity

unilateral UMN: same symptoms but usually mild or transitory

what type of nuclei does the glossopharyngeal (IX) cranial nerve have?

1 sensory nucleus, 2 motor nuclei

where does the glossopharyngeal (IX) nerve receive sensory information from?

taste, ear skin, pharynx, posterior 1/3 of tongue

what does the glossopharyngeal (IX) nerve innervate?

parotid salivary gland, pharynx- stylopharyngeus

associated with gag reflex

what is the innervation pattern of the glossopharyngeal (IX) nerve?

bilateral innervation from UMN system

what type of nuclei does the facial (VII) cranial nerve have?

1 sensory, 2 motor

where does the facial (VII) nerve receive sensory information from?

anterior 2/3 of tongue, glands

what does the facial (VII) nerve innervate?

facial expression, stapedius, glands, neck muscles

what is the innervation pattern of the facial (VII) nerve?

bilateral innervation to upper face, contralateral innervation to lower face

what happens when the unilateral LMN of the facial (VII) nerve are damaged?

weakness on entire side of face on side of lesion, ordinary sounds might seem loud

what happens when the unilateral UMN of the facial (VII) nerve are damaged?

mild or transitory to forehead, paralysis/paresis to lower facial muscles opposite side of lesion

what happens if there is UMN damage to the left facial nerve?

affects facial movement on lower right side, mildly affects all upper face movement

what type of nuclei does the vagus (X) cranial nerve have?

1 sensory, 2 motor

where does the vagus (X) nerve receive sensory information from?

tongue, external ear, thoracic and abdominal viscera, internal surfaces of laryngopharynx and larynx

what are the branches of the vagus (X) nerve?

pharyngeal

superior laryngeal → internal and external

recurrent laryngeal

what does the vagus (X) nerve innervate?

pharyngeal branch: pharynx, soft palate

superior laryngeal nerve branch: inferior constrictor, cricothyroid, assist pharynx/palate

recurrent laryngeal nerve branch: intrinsic muscles of larynx

visceral: thoracic and abdominal area

what is the innervation pattern of the vagus (X) nerve?

bilateral innervation from UMN system

what happens when the unilateral LMN of the vagus (X) nerve are damaged?

paralysis of ipsilateral vocal cord, perceptual voice characteristics are hoarse and breathy voice

what happens when the unilateral UMN of the vagus (X) nerve are damaged?

rough, harsh voice, rarely VF paralysis

what happens when the bilateral UMN of the vagus (X) nerve are damaged?

rough, hard, strained, tense voice, rarely VF paralysis

what type of nuclei does the hypoglossal (XII) cranial nerve have?

1 motor nucleus

what does the hypoglossal (XII) nerve innervate?

intrinsic and extrinsic muscles of tongue, genioglossus

what is the innervation pattern of the hypoglossal (XII) nerve?

contralateral innervation to genioglossus and bilateral innervation to tongue muscles

what happens when the unilateral LMN of the hypoglossal (XII) nerve are damaged?

ipsilateral side will look shrunken, tongue fasciculations, tongue deviates ipsilaterally to weaker side

what happens when the unilateral UMN of the hypoglossal (XII) nerve are damaged?

tongue deviates contralateral to side of lesion

what happens when there is any bilateral damage to the hypoglossal (XII) nerve?

difficulty protruding or moving tongue

what spinal nerves innervate the diaphragm?

phrenic nerve

what happens when the unilateral LMN of the spinal nerves are damaged?

not severe, if diaphragm weak, can cause- severe respiratory abnormalities

what happens when the unilateral UMN of the spinal nerves are damaged?

abnormal breathing patterns, severe respiratory abnormalities, death

what is the overall function of the control circuits?

contribute to control and programming of speech motor system beyond muscular execution

influence movement by interacting with cortex, not directly with nerves

what is the function of basal ganglia direct pathway?

facilitates movement by pathway of inhibition

what is the function of the basal ganglia indirect pathway?

inhibits movement

what are the structures in the direct pathway of the basal ganglia control circuit?

cortex → striatum → globus pallidus internal → thalamus → cortex