General Organization of the Central Nervous System Lobes 3

Question 1

Cranial Nerve 1 and 2enter the brain where?

Where do all the others enter or emerge?

Answer 1

CN1 Olfactory directly attaches to the cerebral hemispheres
CN2 Optic Nerves are outgrowths of the Diencephalon (outgrowth of the brain). Optic tract directly attaches to the diencephalon.
CN3-12 brainstem.

Question 2

What happens when basal ganglia are damaged?

Answer 2

They all cause distinct movement disorders. such as
Involuntary movements
Generalized alterations in muscle tone.

Question 3

Name the 5 Nuclei of the Basal Ganglia

Answer 3

Putamen
Caudate nucleus
Globus pallidus....main loop
Subthalamic nucleus
Substantia nigra...secondary input.

Question 4

What are the 2 primary rules for Primary Afferents?

Answer 4

Most always synapse on the ipsilateral (same) side with second-order neurons.
They begin with dendrites in the peripheral nerves, synapse in the CNS.

Question 5

What are the 3 primary rules for Lower Efferent Motor Neurons?

Answer 5

These exit the CNS without crossing the midline.
Only the axon of a lower motor neuron is contained in a peripheral nerve.
Cell body and dendrites are in the CNS

Question 6

What 3 things do Somatosensory inputs do?

Answer 6

1. Feed into local reflexes.
2. Distribute to the cerebellum.
3. Distribute to the cerebral cortex via the thalamus.

Question 7

What are the 6 “body senses” for somatosensory input?

Answer 7

1. Nociception (pain)
2. Temperature
3. Simple touch
4. Proprioception
5. Kinesthesia (perception of movement)
6. Stereognosis (perception of size and shape of objects by touch)

Question 8

What are the 3 rules for Somatosensory Inputs?

Answer 8

Except for taste and smell, these pathways cross midline before reaching the thalamus and on to the postcentral gyrus.

Thalamocortical fibers are uncrossed.

It takes a minimum of 3 neurons to reach the postcentral gyrus due to the rules.

Question 9

What are primary afferents that terminate without crossing the spinal cord?

Answer 9

reflexes.

Question 10

What type of input would project bilaterally to the thalamus?

Answer 10

Localization of sound.

Question 11

What is the function of the Cerebellum?

Answer 11

Receives large amounts of sensory information.

Uses this for coordination of movement, not perception of movement.

Question 12

What is the general rule for the Cerebellum?

How many pathways?

Answer 12

Somatosensory information to the cerebellar cortex remains ipsilateral.
Can be as few as 2 neurons in a pathway.

Question 13

Lower motor neurons are influenced by what 3 things?

Answer 13

Reflex circuitry (can be biased by spinal level).
Descending fibers from the brainstem
Upper motor neurons: coricospinal tract neurons (primary motor cortex).