Vestibular System And Cerebellum - 4/26 Stephens Flashcards
Where does the vestibular nerve enter the brainstem And how does it course?
Pontomedullary sulcus and courses beneath (anterior to) the restiform body
Which structure serves as the critical link in the Oculomotor system and serves control horizontal gaze?
What CNs associated?
MLF
CN 3,4,6
The Paramedian Pontine Reticular Formation (PPRF) sends fibers to where?
Where does it also project fibers to?
Abducens nucleus on ipsilateral side
Contralateral MLF to contralateral Oculomotor nucleus
Where does the lateral vestibuospinal tract (LVST) originate from?
Terminates where?
Responsible for what?
Lateral vestibular (Deiter’s) nucleus
Ipsilateral intermediate gray of spinal cord
Extensor tone and reflexes of antigravity axial and appendicular musculature
The flocculonodular lobe sends info to where?
Then where?
Eventually output goes to where?
Via what?
Fastigial nucleus
Vestibular nuclei
Axial musculature
MVST and LVST
The Fastigial nucleus sends info to the vestibular nuclei but can also send information to where?
Goes where next?
Finally to what?
Via what?
Ventral lateral nucleus
Primary motor cortex
Axial musculature
Anterior corticospinal Tract
Doll’s eyes maneuver is testing what movement of the eyes?
What CNs involved?
Horizontal gaze
3, 6
If the head turns to the right and the right eye ADDucts but the left eye remains neutral, where is the lesion?
CN 6
If the head turns to the right and the right eye is neutral and the left eye ABducts where is the lesion?
CN 3
If the head turns to the right or left and there is no response of the eyes (neutral gaze) where is the lesion?
Midbrain damage
In caloric testing of the ears, if there is no response from the left or right ear, what is lesioned?
CN 8 nerve palsy Midbrain damage (deep coma state)
In caloric testing of the left ear, if the right eye ADDucts and the left eye has no response, where is the lesion?
CN 6
A unilateral lesion to the MLF superior to the Abducens nerve results in what?
What muscle is impaired?
Contralateral disturbance of horizontal gaze
middle rectus of ipsilateral eye
Patients with a right side INO have abnormal horizontal gaze in which direction?
Left (opposite side)
How do you name INO?
How do you name a lesion to the right MLF?
According to side of Oculomotor impairment
Lesion to Right MLF means right horizontal gaze normal and left horizontal gaze impaired
Therefore Right INO
Unilateral lesion of the PPRF results in what?
Lesion of Left PPRF results in what?
Paralysis of horizontal gaze on the same side of the lesion
Inability to move both eyes in conjugate horizontal gaze to the left
Which nucleus of the cerebellum is the most medial and has vestibular connections and function?
Fastigial nucleus
Which nucleus of the cerebellum projects to the red nucleus and is where the majority of efferents from the neocerebellum originate?
Dentate nucleus
The Fastigial nucleus sends information to the vestibular system via what?
Inferior cerebellar peduncle
The Dentate nucleus sends out cerebellar efferents via what?
Superior cerebellar peduncle
What does the dorsal spinocerebellar tract (DCST) convey?
Unconscious, PRECISE proprioception to LOWER half of the body and extremities
What does the Direct Arcuate Fibers/Cuneocerebellar Tract convey?
Unconscious PRECISE proprioception to the UPPPER half of the body and extremities
What does the Trigeminocerebellar Tract convey?
General proprioception to the head
What do the olivocerebellar fibers represent and terminate as?
Afferent fibers that originate in the ION and terminate as climbing fibers in the contralateral cerebellar hemisphere
What tract is the critical link between the extrapyramidal system and the cerebellum?
Where does it arise from?
Central Tegmental Fasciculus (CTF)
Red nucleus, PAG, midbrain Tegmentum
Which structures course through the Inferior cerebellar peduncle (Restiform body)?
DDT Always Ruins Olives
DCST DAF Trigem AF RF Olivo Fibers
What forms all of the middle cerebellar peduncle?
Pontocerebellar fibers
What does the Ventral Spinocerebellar Tract (VSCT) convey?
General proprioception from lumbosacral (lower limb) to the cerebellum
What does the Trigeminocerbellar Tract convey?
PRECISE tactile and proprioceptive info from head to the cerebellum
Both the VSCT and Trigeminocerbellar tract course through what before terminating on the anterior vermis of the cerebellum?
Superior Cerebellar Peduncle
What is a major cerebellar efferent pathway?
Dentato-rubro-thalamic pathway
What is the only efferent from the cerebellar cortex?
Where does it terminate?
Purkinje cells
Deep cerebellar nuclei
What are the most direct afferents to the cerebellar cortex?
Terminals of what?
Excite what?
Climbing fibers
Olivocerebellar fibers
Purkinje cells
What are some major clinical signs of cerebellar lesions?
Dysmetria
Dysdiadochokinesia
Asthenia
Dysdiadochokinesia, dysmetria, nystagmus and intention tremors bilaterally indicate what type of condition?
Friedreich’s Ataxia
The long central processes of the neurons from what form the vestibular nerve?
Where is it found?
Vestibular (Scarpa’s) ganglion
Vestibular portion of the membranous labyrinth
