Lecture 9 Flashcards
What 2 types of fibers do cranial nerves consist of?
Efferent motor and afferent sensory fibers
Efferent motor fibers vs. Afferent sensory fiber origins
efferent motor fibers: originate in the nuclei of the brainstem:: afferent sensory fibers: originate in the peripheral ganglia (trigeminal ganglia)
Cranial nerves receive bilateral UMN innervation. T or F?
True
w/ the exception of portions of CN V, VII, & XII
Corticobulbar pathways cross over at the level of _________.
the CN nuclei
Trigeminal nerve (CN V) is not a mixed nerve. T or F?
False; it is a mixed nerve.
It has both motor and sensory functions.
Where do the motor and sensory roots of the trigeminal nerve attach?
The Pons
motor roots vs. sensory pathway nuclei (CN V)
motor nuclei: restricted to Pons:: sensory pathways: cell bodies in trigeminal ganglia & terminate in trigeminal sensory nucleus
What muscles does the trigeminal nerve innervate?
- muscles closing/ opening the jaw
- muscle of velopharyngeal closure
- muscle tensing in the tympanic membrane
Sensory innervation of the Trigeminal nerve
Opthalmic nerve, maxillary nerve, mandibular nerve
What are the the 5 functions of the Trigeminal nerve?
- Mastication
- Articulation
- Tensing/closure of the soft palate
- hyolaryngeal elevation
- sensation to the face, teeth, gums, & anterior 2/3 of the tongue
(MATHS)
During trigeminal nerve motor testing where the jaw is supposed to open freely against resistance, the jaw will deviate towards the weak side of what muscle?
pterygoid muscle
weakness of the lateral pterygoid is expressed as ?
difficulty moving in the opposite direction
unilateral UMN damage vs. unilateral LMN damage (CN V)
unilateral UMN damage: no significant motor defecits :: unilateral LMN damage: mandible deviates towards side of paralysis or paresis during opening; hyptonia & atrophy; impaired hyolaryngeal elevation
bilateral UMN damage vs. Unilateral LMN damage (CN V)
bilateral UMN damage: hypertonia; slow movements; restricted jaw opening/closing; reduced hyolaryngeal elevation :: bilateral LMN damage: hypotonia; impaired jaw opening/closing; impaired hyolaryngeal elevation
(note: HYPERtonia vs HYPOtonia)
The facial nerve (CN VII) is a mixed nerve, T or F?
True; both motor and sensory functions.
Roots are attached to the PONS.
motor pathways vs. sensory pathways (CN VII)
motor pathways: begin in facial motor nucleues in pons :: sensory pathways: cell bodies in geniculate ganglion; terminate in tractus solitarius (taste) nucleus and trigeminal nerve spinal nucleus (touch)
The facial nerve’s motor branches innervate…
- the muscles of facial expression
- platysma
- stylohyoid
- stapedius
- post. belly of digastric.
(note: the visceral motor branches innervate the lacrimal, submandibular and sublingual glands.)
What two senses do the sensory branches of the Facial nerve innervate?
- special sensory: taste for the ant. 2/3 of tongue, floor of mouth and palate
- touch: external ear and auditory meatus
What are the 4 functions of the facial nerve?
- Movements of facial expression
- supports hyolarngeal elevation
- saliva & tear production
- taste 2/3 of tongue
Two tests for motor testing of facial nerve?
test for facial symmetry
test motor function for upper/lower face
Unilateral UMN damage leads to upper face weakness. T or F?
False; no upper face weakness occurs b/c it is bilaterally innervated.
Contralateral lower face weakness occurs instead.
Bilateral UMN damage leads to ________ of the whole face.
spastic paralysis
Glossopharyngeal nerve (CN IX) Anatomy
- emerges from the medulla
- motor portions originate in nucleus ambiggus in medulla
-sensory components are processed in the nucleus solitarius in the medulla
Motor vs. sensory innervation of glossopharyngeal nerve
motor: innervates the stylopharyngeus muscle:: sensory: post. 1/3 of the tongue, soft palate
What reflex is the glossopharyngeal nerve responsible for?
the gag reflex
the stylopgaryngeus muscle assists in the elevation of the ______ and ______ during _______.
larynx
pharynx
swallowing
To test the sensory part of the glossopharyngeal nerve, what do you test?
the gag reflex
*no test for the motor part
The vagus nerve (X) is the most ________ cranial nerve.
complex
motor portions vs. sensory pathways of vagus nerve
motor portions: originate in the nucleus ambiguus in the medulla:: sensory pathways: cell bodies in inferior ganglia; terminate in the nucleus solitarius in the medulla
What are the 2 main branches of the vagus nerve?
- laryngeal branch
- pharyngeal branch
The laryngeal branch of the vagus nerve innervates…
all the intrinsic laryngeal muscles (except cricothyroid)
The pharyngeal branch of the vagus nerve innervates…
the muscles of the pharynx and muscles of the soft palate.
Vagus nerve’s motor function is responsible for ______ production and ______.
Voice
Swallowing
Sensory function of the Vagus Nerve
- plays role in triggering pharyngeal phase of swallowing
- triggers cough reflex
- allows detection of food/liquid residue after swallow
testing of vagus nerve: palate function
test gag reflex and observe palatal movement during production of “ah”
spinal accessory nerve consists of only _______ nuerons.
motor
what roots does the spinal accessory nerve consist of?
cranial and spinal roots
The cranial nerves join the vagus nerve to innervate the _______ muscles.
palatal
The spinal roots innervate the _________ and _______.
sternocleidomastoid and trapezius
Where does the hypoglossal nerve originate?
In the medulla
What kid of innervation does the hypoglossal nerve receive?
bilateral innervation
exception: neurons that innervate the genioglossus muscle –>only receive contralateral innervation
The hypoglossal innervates the intrinsic and extrensic muscles of the ________.
tongue
3 extrinsic tongue muscles: genioglossus, hypoglossus and styloglossus
The hypoglossal nerve serves to innervate the muscles that are involved in ________ and ________.
articulation and swallowing
Motor testing in the hypoglossal nerve involves?
Looking for: atrophy, fasciculations, tremor/random movements
protrude, push tongue inside cheek and quick movements
Unilateral UMN vs LMN damage of the hypoglossal nerve
Unilateral UMN damage: results in contralateral weakness:: Unilateral LMN damage results in ipsilateral weakness
Bilateral UMN and LMN damage of the hypoglossal nerve results in…
weakness of both sides.
The cranial nerves are innervated by the ________________.
Corticobulbar Tracts
