Neuroanatomy quiz 4

What is the striatum made up of?

The caudate and Putamen

What is the name of the axons that do not cross at the medulla level as they continue down the spinal cord?

The Ventral corticospinal tract

What is the striatum responsible for?

major input nucleus to the basal ganglia

What does the GPI stand for?

internal pallidal segment

What is the GPI responsible for?

It is the major output of the basal ganglia

Which part of the basal ganglia is the only component that sends out excitatory output?

The STN (Subthalamic nucleus)

In Parkison’s, if the pars compacta in the substantia niagra degenerates, what effect will it have on output?

There will be less excitement to the striatum and will result in overall less output

What would increase muscle tone?

Exciting neurons in the basal ganglia

Tardive Dyskinesia is caused by what?

Dopamine Receptor blocking medications leading to receptor sensitivity

Tardive Dyskinesia can lead to _____

Punding

What does Tardive Dyskinesia cause in terms of movement

Involuntary movements

Where do Cocaine and Meth primarily bind to?

Receptors in the Striatum

Which gyrus is the primary motor cortex located?

The precentral gyrus

Posterior limit

Central sulcus separates the motor and sensory areas

Anterior limit

Precentral sulcus

Inferior limit

Lateral sulcus

Damage to which part would cause trouble with playing piano?

Primary motor cortex

Where is the primary somatosensory located?

Postcentral gyrus

What does the internal capsule separate

The caudate and the putamen

Which two structures make up the Lentiform Nucleus?

Putamen

Globus pallidus

What are the two parts of the Globus Pallidus?

GPE

GPI

The caudate makes up the wall of which structure?

Lateral ventricle

In the internal capsule which fibers are ascending and which fibers are descending?

Ascending sensory fibers

descending motor fibers

The putamen lies laterally and medially to which structures?

Laterally- caudate

Medially- insula (inside sylvian fissure)

The lower the D2 receptor activity, the ____ likely an individual will display impulsive behavior

more

The higher the D2 receptor activity, the ____ likely an individual will display impulsive behavior

less

Which of the following is NOT one of the basal nuclei?

caudate nucleus

globus pallidus

putamen

hippocampus

amygdaloid body

hippocampus

amygdaloid body

The direct pathway ____ movement

facilitates

The indirect pathway _____ movement

inhibits

In a NORMAL direct pathway:

The cortex will send an excitatory signal to the CPu. The CPu will then send an inhibitory signal to the GPi. The GPi will then inhibit the thalamus, but the inhibition is reduced. When the inhibition is reduced, it will cause the thalamus to become more active which leads to more excitatory output back to the cortex, resulting in movement. Dopamine from the SNc via D1R will enhance the pathway to promote movement.

In a NORMAL indirect pathway

The cortex will send excitatory signals to the CPu which will send inhibitory signals to the GPe. The GPe will then inhibit the STN but this will disinhibit the STN causing it to send an excitatory signal to the SNr and GPi. The GPi from there will send an inhibitory signal to the Thalamus, reducing its activity and consequently supressing movement

Which pathway will Parkinsons effect?

the direct pathway

Which pathway will hunningtons or hemiballisma effect?

The indirect pathway

In parkinsons

There will be decreased cortical output which will cause difficulty initiating movements. The SNc will not send as strong of an excitatory signal (thin blue arrow) to the CPu. This will cause the inhibitory signal that is sent to the GPi to be weaker (thinner).

Somatotopic representation

The size of the body part is proportional to the complexity of its movement

Which structures that are controlled by the primary motor cortex are near the midline?

The foot and leg

The activity of the motor cortex and the brainstem is influenced by which structure?

The basal ganglia and cerebellum

The corticospinal tract

massive collection of axons ORIGINATING in the Betz pyramidal cell, in layer V of the primary motor cortex

Where do the axons of the CST converge?

The posterior limb of the internal capsule

Lower Medulla Oblangata

The corticospinal axons cross over to the contralateral side (pyramidal decussation) and then continue their descent through the brainstem and spinal cord as the lateral corticospinal tract

Where do the CST axons that do not cross over to the contralateral side shortly before reaching their target, the lower motor neurons, located in the anterior horn of the spinal cord cross over?

The lower level

If the lesion is in the Dorsal horn which side of the body will there be pain relief?

The ipsilateral side

What is the effect on temperature that a lesion in the dorsal horn may lead to?

Temperature runs medically so it will not be affected

Less inhibition on the GPI results in (less/more) output

increase

More inhibition on the Thalamus (increase/ decrease) output of the thalamus

decrease

If excitation to the cortex is decreasing what will happen to the cortical output?

Decrease

What will happen to motor movements if the cortical output decreases?

Less voluntary movement (difficulty initiating movements)

Which cells degenerate in the striatum to cause Hunningtons?

mediospiny neurons, which have D2 receptors, degenerate in the straitum

Due to the degeneration of the mediospiny neurons, which (increases/ decreases) the output,

Decrease

The degeneration of mediospiny neurons will result in (more/less) inhibition on the GPE

less

Less inhibition on the GPE will lead to (greater/lesser) output of the GPE

increase

If the STN is more inhibited, what will happen to its output?

Decrease

If there is less excitation to the GPI and SNr due to decreased STN output, what will happen to the output?

Decrease

If the output of the GPI and SNr is decreased, then what will happen to the Thalamus?

It will be disinhibited

If the Thalamus is disinhibited, what will happen to its output

Increase

What will happen to cortical output if the thalamus has increased output

increase

The indirect pathway results _____ movements

involuntary