Module 11

Question 1

What is the primary function of the cerebellum?

Answer 1

Question 2

Which deep cerebellar nuclei are associated with the medial, intermediate and lateral zones, respectively?

Answer 2

Question 3

What structures make up the vestibulocerellum, spinocerebellumand cerebrocerebellum, respectively?

Answer 3

Vestibulocerebellum: Flocculonodular lobe & the Fastigial nucleus; Vestibular nerve & nuclei

Spinocerebellum: Medial (vermal) & Intermediate zones and the Fastigial & Interposed nuclei; Ispilateral proprioceptive information

Cerebrocerebellum: Lateral zone & Dentate nucleus; Sensorimotor cortices; Red nucleus; Pontine nuclei

Question 4

What are the main functions of the vestibulocerebellum, spinocerebellum and cerebrocerebellum, respectively?

Answer 4

Question 5

Which cells of the cerebellum influence the firing rate of the neurons of the deep cerebellar nuclei?

Answer 5

The Purkinjie cells are inhibitory neurons that are the final output cell of the cerebellar cortex. They project from the cortex to the deep cerebellar nuclei.

Question 6

What is ataxia?

Answer 6

The abscence of coordination and movement

Question 7

What is the difference between dysmetria and intention tremor?

Answer 7

Intention tremor: oscillatory trajectory during target- directed movements- pronounced at the end point of the movement; tremor is absent at rest

Question 8

What clinical signs would you expect to see when working with someone with an injury to the cerebellum?

Answer 8

Question 9

Which of the following cerebellar peduncles will convey information about the motor plan from the cortex to the contralateral cerebellum?
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle

Answer 9

Middle cerebellar peduncle

Explanation:
The middle cerebellar peduncle: the corticopontine tract will project to the ipsilateral pontine nuclei. The pontine nuclei will send their axons across the pons to enter the contralateral cerebellum via the middle cerebellar peduncle. This is how the motor plan generated by the sensorimotor cortices of one hemisphere is conveyed to the contralateral cerebellum.

Question 10

True or False: Proprioceptive information and vestibular information from one side of the body is projected to the ipsilateral cerebellum via the inferior cerebellar peduncle.

Answer 10

True

Explanation:
This statement is true: proprioceptive and vestibular information from one side of the body is conveyed to the ipsilateral cerebellum via the inferior cerebellar peduncle.

Question 11

Which of the following types of information is NOT conveyed to the cerebellum via mossy fibers?
Proprioceptive information
Vestibular information
Integrated information from the inferior olivary complex
Information about the motor plan

Answer 11

Integrated information from the inferior olivary complex

Explanation:
Proprioceptive and vestibular information (which allows the cerebellum to have information about the movement being produced) and information about the motor plan is conveyed to the cerebellum by mossy fibers. Climbing fibers carry information from the inferior olivary complex (important for signalling motor error).

Question 12

Which deep nucleus is associated with the lateral zone of the cerebellar cortex?
Fastigial
Interposed
Dentate

Answer 12

Dentate

Explanation:
The dentate nucleus is associated with the lateral zone. The fastigial nucleus is associated with the medial (vermal) zone, and the interposed nuclei are associated with the intermediate zone.

Question 13

Which of the following cerebellar modules will modulate upper motor neurons of the brainstem that are part of the ventromedial system? Select all that apply.
Vestibulocerebellum
Spinocerebellum (vermal zone)
Spinocerebellum (intermediate zone)
Cerebrocerebellum

Answer 13

Vestibulocerebellum
Spinocerebellum (vermal zone)

Explanation:
The vestibulocerebellum and the vermal zone of the spinocerebellum will modulate upper motor neurons that give rise to the reticulospinal and vestibulospinal tracts. The intermediate zone of the spinocerebellum and the cerebrocerebellum will modulate upper motor neurons that give rise to the tracts of the dorsolateral system.

Question 14

True or False: The interposed nuclei will output to the contralateral limb regions of the motor cortex (via a relay in VL of the thalamus), and the red nucleus to modulate upper motor neurons of the corticospinal and the rubrospinal tracts, respectively.

Answer 14

True

Explanation:
This statement is true: the intermediate zone of the spinocerebellum will output to the interposed nuclei of the cerebellum, which project to the contralateral limb regions of the motor cortex (via a relay in VL of the thalamus) and the red nucleus. This is how the spinocerebellum modulates UMN of the corticospinal tract and the rubrospinal tract.

Question 15

The dentate nucleus will project to which of the following areas of the brain. Select all that apply.
Contralateral limb regions of the motor cortex via a relat in the VL of the thalamus.
Contralateral red nucleus
Bilateral vestibular nuclei
Bilateral reticular formation
Trunk region of the contralateral motor cortex via a relay in VL of the thalamus

Answer 15

Contralateral limb regions of the motor cortex via a relat in the VL of the thalamus.
Contralateral red nucleus

Explanation:
The denate nucleus is the source of the final output of the cerebrocerebellum. It outputs to the contralateral limb regions of the motor cortex via a relay in VL of the thalamus, and the contralateral red nucleus. UMN of the vestibular nuclei and reticular formation are modulated by output from the fastigial nucleus (both vestibulocerebellum and spinocerebellum). Finally, UMN of the trunk region of the contralateral motor cortex are modulated by output from the fastigial nucleus (spinocerebellum).

Question 16

Which of the following cells of the cerebellar cortex receives excitatory input from mossy fibers?
Granule cells
Stellate cells
Purkinjie cells

Answer 16

Granule cells

Explanation:
The Granule cells of the cortex receive excitatory input from the mossy fibers (which convey information about the motor plan and the movement as it is unfolding). Stellate cells are inhibitory neurons of the molecular layer that receive exciatory input from granule cells. The Purkinjie cells are inhibitory neurons that are the final output cell of the cerebellar cortex. They project from the cortex to the deep cerebellar nuclei.

Question 17

True or False: The Granule cell parallel fibers will project to the molecular layer to synapse with multiple Purkinjie cell dendrites.

Answer 17

True

Explanation:
This statement is true: the Granule cells will project their axons (called parallel fibers) to the molecular layer of the cerebellar cortex to synapse with multiple Purkinjie cell dendrites.

Question 18

True or False: Mossy fibers form multiple excitatory synaptic connections with one Purkinjie cell and are thought to provide an important “training signal” related to motor error.

Answer 18

False

Explanation:
This statement is false: climbing fibers (from the inferior olivary complex) form exciatory synaptic connections with one Purkinjie cell and are thought to provide an important “training” signal related to motor error.

Question 19

True or False: The firing pattern of the deep cerebellar nuclei cells are modified by the excitatory input from mossy fibers and climbing fibers, and the inhibitory input from the cerebellar cortex via Purkinjie cells.

Answer 19

True

Explanation:
This statement is true: the excitatory outflow (firing pattern) of the deep cerebellar nuclei varies in response to: excitatory input from afferent collaterals of the Mossy and Climbing fibers, and inhibitory Input from the cerebellar cortex mediated by the Purkinje cells.

Question 20

What neural pathways regulate the size of the pupil?

Answer 20

Pupillary constriction (aka miosis): involves activation of the sphincter pupillae:
-Neural pathway involves the parasympathetic division of the ANS:
-Edinger- Westphal nucleus (EWN) of CN
III: preganglionic neurons
-Ciliary ganglion: post-ganglionic neurons

Pupilary dilation (aka mydrias): involves activation of the dilator pupilae:
-Neural pathway involves the sympathetic system:
-Intermediolateral cell column: T1-T3
preganglionic neurons
- Superior cervical ganglion: post-
ganglionic neurons

Question 21

Are saccades gaze stabilizing or gaze shifting movements?

Answer 21

Gaze Shifting

(scanning)

Question 22

How are visual scanning and tracking different?

Answer 22

Saccades (scanning)= faster
Smooth pursuits (tracking) = slower

Question 23

Which gaze centers mediate horizontal and vertical saccades, respectively?

Answer 23

Horizontal gaze center
Vertical gaze center

Question 24

Under typical circumstaces, are voluntary saccades initiated by the frontal eye fields or the superior colliculus?

Answer 24

Frontal Eye Fields = voluntary saccades

Explanation:
Superior colliculus= reflexive saccades

Question 25

What happens during activation of the near triad?

Answer 25

Question 26

What clinical signs would you expect tot see if the person you are evaluating had damage to the right medial longitudinal fasciculus versus damage to the left horizantal gaze center?

Answer 26

Question 27

What clinical signs would you expect to see if the person you are evaluating had an acute injury to the right frontal eye fields?

Answer 27

Right lesion--> unable to look to the left (deviated towards the side of lesion) overtime, patient will regain ability to move eye to the right again

Question 28

In order to look to the right, you need to activate which of the following muscles? Left lateral rectus and right medial rectus Right lateral rectus and left medial rectus Right and left medial rectus

Answer 28

Right lateral rectus and left medial rectus Explanation: In order to look to the right, you need to move the eyes to the right. This involves abduction of the right eye (mediated by the right lateral rectus) and adduction of the left eye (mediated by the left medial rectus). The first choice would be mediate looking to the left, and the last choice would produce movement of the eyes toward the nose (this will occur during convergence).

Question 29

Which neural pathway provides innervation of muscles that allow for lens accommodation and pupillary constriction? Communication between preganglionic neurons of the intermediolateral cell column and superior cervical ganglion Communication between preganglionic neurons of the EWN and the ciliary ganglion Communication between the preganglionic neurons of the EWN and the superior cervical ganglion

Answer 29

Communication between preganglionic neurons of the EWN and the ciliary ganglion Explanation: Lens accommodation and pupillary constriction are mediated by two smooth muscles: ciliary muscle and the sphincter pupillae. Both of these muscles are activated by a parasympathetic pathway that begins with viceromotor neurons of the EWN (preganglionic neurons) and post-ganglionic neurons of the ciliary ganglion. Short ciliary nerves originating is this ganglion will innervate the ciliary and sphincter pupillae muscles. Communication betweeen preganglionic neurons of the intermediolateral cell column (lateral horn of the spinal cord) communicate with post-ganglionic neurons of the superior cervical ganglion as part of the sympathetic pathway that mediates contraction of the dilator pupillae and the tarsal muscles

Question 30

Your patient presents with ptosis of the eye and a constricted pupil. Based on this information you conclude which of the following? CN III palsy CN VI palsy Injury to the superior cervical ganglion

Answer 30

Injury to the superior cervical ganglion Explanation: Ptosis of the upper eyelid and a constricted pupil is an indicator of damage along the neural pathway that provides innervation to the tarsal muscles and the dilator pupillae (sympathetic pathway). CN III palsy would result in ptosis as well, but with a dilated pupil and the eye would be positioned in a "down and out" position in the orbit. CN VI palsy would result in an esotropia and an inability to abduct the ipsilateral eye.

Question 31

True or False: Conjugate eye movements involve movement of the eyes in the same direction.

Answer 31

True Explanation: This statement is true: conjugate eye movements involved movement of the eyes in the same direction (look right - both eyes move to the right). NOTE: disconjugate eye movements involve movement of the eyes in the opposite direction (look in at your nose - your right eye moves to the left and your left eye moves to the right).

Question 32

Which of the following is a gaze shifting movement? Select all that apply. Vestibulo-ocular reflex Saccades Smooth Pursuits Vergence

Answer 32

Saccades Smooth Pursuits Vergence Explanation: There are two types of eye movements: gaze stabilizing and gaze shifting movements: gaze stabilizing movements include the VOR. All of the others are gaze shifting movements.

Question 33

True or False: The left horizontal gaze center will produce a horizontal saccade to the right.

Answer 33

False Explanation: This statement is false: the right horizontal gaze center will activate LMN that will produce a right horizontal saccade (movement of the eyes to the right).

Question 34

Neurons is the right horizontal gaze center will activate neurons in which of the following nucleus? Abducens nucleus on the left Abducens nucleus on the right Oculomotor nucleus on the left

Answer 34

Abducens nucleus on the right Explanation: The right horizontal gaze center will activate neurons in the right abducens nucleus (activating LMN to the right lateral rectus and internuclear neurons that contact the left oculomotor nucleus via the medial longitudinal fasciculus).

Question 35

True or False: The frontal eye fields are the UMN that will send commands to control voluntary saccades.

Answer 35

True

Question 36

The tectoreticulospinal system will out put to which of the following areas? Select all that apply. Horizontal gaze center Vertical gaze center Medial located LMN in the cervical segments of the spinal cord Laterally located LMNs is the cervical segments of the spinal cord

Answer 36

Horizontal gaze center Vertical gaze center Medial located LMN in the cervical segments of the spinal cord Explanation: The superior colliculus will project to the gaze centers in the brainstem (control of eye movements) and to medially located LMN in the cervical segments of the spinal cord (control of head and neck movements).