Lecture 8: CN VII-XII cont. Flashcards
Vestibular system
-location:
posterior bony labyrinth
oriented at approximately 30 degrees elevation anteriorly when looking forward.
What components make up the vestibular system:
Otolith Organs - Saccule and Utricle
Semicircular Canals (Horizontal, Anterior, Posterior)
Vestibular system
Hair cells only cilia exposed in ______. Multiple sterocilia with _______ kinocilium.
Sterocilia tilt to kinocilium = _______ depolarization
endolymph; 1
increased
The maculae (special dectors) is located in both the ________ and _______ and consist of cilia of hair cells covered by a layer of _________ (otoconia).
If there is a dislodge of (otoconia) into the semicircualr canal it can cause
saccule and utricle; CaCO3 crystals
BPPV
What structure is responsible for linear acceleration and head tilts in the horizontal axis:
-displacements?
utricle
anterior tilted up 30º
A/P (forward/backwards) side/side (head tilts)
What structure is responsible for vertical linear acceleration:
-displacements?
saccule
vertical alignment and A/P
When tilting your head backwards the sterocilia moves away from the kinocilium but when coming back forward the __________ affects happens
opposite
The semicircular canal has one end open but the other end blocked by the _________
ampulla
The cell bodies of the hair cells within the crista are embedded in the crista and surrounded by ___________.
The cilia of these hair cells project into the cupula within the ampulla, and are surrounded by ________.
perilymph
endolymph
What is the function of the semicircular canals:
detect angular acceleration or deceleration; dynamic activation or inhibition
The following statement is true or false.
The lateral/horizontal semicircular canals are in opposite planes.
false; same
Canal Orientation: Horizontal Semicircular Canals:
–Kinocilia face ________ the utricle.
Anterior and Posterior Semicircular Canals:
–Kinocilia face ______ from the utricle.
toward
away
When rotating the head Inertia causes endolymph (fluid within the semicircular canals to move in the _______ direction.
opposite
Rotating Head Side to Side (Transverse Plane):
-activates:
-inhibits:
ipsilateral (same side) horizontal canal.
Inhibits the contralateral (opposite side) horizontal canal.
Rotating Head Downward/Forward to Left or Right:
-activates: (2)
the anterior and contralateral posterior canals
________ maneuver decreased 2/3 falls in community dwelling geriatric pop.
Epley’s
Vestibular pathway to the neocortex is a ____ order neuron.
3
Vestibular pathway has conscious awareness of ______ in space.
1º neuron:
2º neuron:
3º neuron:
body
1- scarpa’s ganglion
2- vestibular nuclei (superior/inferior, lateral/medial)
3- B VPM of thalamus integrate with proprioception from other parts in VPL
Vestibular-ocular reflex (VOR): vision stabilization
Turning head activates ________ horizontal canal and ______ contralateral one.
(+) ipsilateral; (-) contralateral
Vestibular-ocular reflex (VOR): vision stabilization
Signal conducted to the _______ vestibular nucleus. which activates contralateral ______ nucleus.
medial; CN VI
Vestibular-ocular reflex (VOR): vision stabilization
Activation of the contralat. CN VI from the medial vestibular nuclei (MVN) activates the contralateral _______ rectus.
Activates contralateral _______ nucleus, THEN contralateral _______ rectus will be activated.
lateral
CN III; medial
Vestibular-ocular reflex (VOR): vision stabilization
CN VI on the ipsilateral side is ______ and ipsilateral lateral rectus and contralateral medial rectus are ________
Results: turning head to one side, both eyes rotate______ to fix on target.
inhibited; inhibited
oppositely
The vestibulo-cervical spinal reflex (VCR/VSR) = _______ control. Integrated vestibular and proprioceptive signals by ______
postural; cerebellum
The vestibulo-cervical spinal reflex (VCR/VSR) inputs to _______ and ________ vestibular nucleus.
lateral & medial
The vestibulo-cervical spinal reflex (VCR/VSR)
The lateral vestibulospinal tract: controls _______ proximal extremity muscles, but proximal can be very _______.
ipsilateral; distal
The vestibulo-cervical spinal reflex (VCR/VSR)
The medial vestibulospinal tract controls:
bilateral trunk, *mainly neck and upper body
Tract axons for (VOR) and (VCR/VSR)
VOR= MLF, ascending limb
VCR/VSR = MLF, ascending limb
What CN innervates the following structures:
External ear:
Posterior 1/3 of tongue
Pharynx and larynx:
CN: VII, IX, X
CN: IX
CN: X
Functions of CN IX and X: bilateral _______ control
corticobubular coordinated and precise control)
Impairment to CN IX and X can lead to ________ and ______
dysphagia; dysarthia
What is the function of the lesser petrosal nerve, a branch of cranial nerve IX (glossopharyngeal nerve)?
What does the glossopharyngeal nerve (CN IX) monitor in the carotid sinus and carotid body?
It carries parasympathetic fibers to the otic ganglion, which innervates the parotid gland
The carotid sinus is sensitive to changes in blood pressure (baroreceptors - mechanical stimuli), and the carotid body detects changes in oxygen concentration (SaO2 - chemical stimuli).
What does the vagus nerve (CN X) monitor in the aortic arch?
What regions do the vagus nerve (CN X) carry visceral sensory information from?
It monitors baroreceptors in the aortic arch, providing information about changes in blood pressure.
Internal organs until end of midgut
What are the target structures of the parasympathetic fibers originating from Cranial Nerve III (Oculomotor Nerve) when they synapse at the ciliary ganglion?
Ciliary body (for accommodation of the lens) and pupillary sphincter (for pupil constriction).
Where do parasympathetic fibers from Cranial Nerve VII (Facial Nerve) synapse to innervate lacrimal and sinus mucosal glands?
Pterygopalatine ganglion.
What are the target glands innervated by the parasympathetic fibers from Cranial Nerve VII (Facial Nerve) when they synapse at the submandibular ganglion?
Submandibular and sublingual salivary glands.
Which ganglion is involved in the parasympathetic innervation of the parotid gland, and through which cranial nerve does it originate?
Otic ganglion; Cranial Nerve IX (Glossopharyngeal Nerve).
Where do the parasympathetic fibers from Cranial Nerve X (Vagus Nerve) synapse, and what regions do they innervate?
They synapse in ganglia within target organs. They innervate visceral organs until the end of the midgut.
Which sacral spinal nerves contribute to the formation of the pelvic splanchnic nerves, and what is their target region?
Pelvic splanchnic nerves are formed by spinal nerves S2, S3, and S4. Their target regions include the hindgut and pelvic visceral organs.
Which nuclei in the upper cervical spinal cord receive bilateral corticobulbar innervation, and what is their origin?
Nuclei from C1 to C5 receive bilateral corticobulbar innervation. The rootlet from the medulla runs to Cranial Nerve X (Vagus Nerve).
Where are the nuclei located in the upper cervical spinal cord that receive bilateral corticobulbar innervation?
Answer: The nuclei are located in the lateral _________ not from _______
spinal cord; ventral rami.
Which cranial nerve is crossed by the rootlet from the medulla that runs from C1 to C5?
Cranial Nerve X (Vagus Nerve).
What muscles are involved in somatic motor function when crossing the jugular foramen with Cranial Nerves IX and X?
Sternocleidomastoid and trapezius muscles.
What condition is associated with torticollis, and what are its characteristic features?
Answer: Torticollis is associated with __________ sternocleidomastoid (SCM) tightness and ________ rotation. It can manifest as ipsilateral __________ or contralateral_________, indicating muscle balance problems.
ipsilateral; contralateral; tightness; weakness
nuclei in the proximal medulla receive
contralateral corticobulbar innervation
CN XII: Hypoglossal
What is a characteristic feature of upper motor neuron (UMN) damage in terms of muscle atrophy?
What is a characteristic feature of lower motor neuron (LMN) damage in terms of muscle atrophy?
UMN damage typically presents with no obvious atrophy.
LMN damage typically presents with obvious atrophy.
CN XII: Hypoglossal
Fibers exit the ______ and pass through the anterolateral sulcus, positioned between the _______ and the _______.
medulla; pyramid and the olive.
What type of muscles are exclusively innervated by the hypoglossal nerve (CN XII).
What is a manifestation of muscle imbalance?
Only somatic motor: extrinsic and intrinsic tongue muscles.
Protrusion of the tongue may push to the affected/weak side, indicating muscle imbalance.
