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50 Cards in this Set

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  • Back
The brain has three main divisions. What are they?
1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)
The prosencephalon is divided into two sections. What are they?
1. Telencephalon
2. Diencephalon
The telencephalon consists of what neuroanatomical structures?
1. Cerebral cortex
2. Subcortical white matter
3. Basal ganglia
4. Basal forebrain nuclei
The diencephalon consists of what neuranatomical structures?
1. Thalamus
2. Hypothalamus
3. Epithalamus
The mesencephalon consists of what neuroanatomical structures?
1. Cerebral peduncles
2. Midbrain tectum
3. Midbrain tegmentum
The rhombencephalon is divided into two sections. What are they?
1. Metencephalon
2. Myelencephalon
The metencephalon consists of what structures?
1. Pons
2. Cerebellum
The myelencephalon consists of what structure?
Medulla
What is an action potential?
A transient voltage change that occurs when excitatory synaptic inputs combine with endogenous transmembrane currents to sufficiently excite a neuron.
How long do action potentials last?
Approximately 1 millisecond
How fast can action potentials travel?
Up to 60 meters per second
What do action potentials do?
They trigger a release of neurotransmitter molecules from synaptic vesicles, allowing chemical communication with the postsynaptic cell.
What are oligodendrocytes?
They are myelin-forming glial cells in the central nervous system.
What are Schwann cells?
They are myelin-forming glial cells in the peripheral nervous system.
What are nodes of Ranvier?
They are short exposed segments of the axon, where voltage-gated ion channels are concentrated.
What are some common terms for white matter pathways in the central nervous system?
1. Tract
2. Fascicle
3. Lemniscus
4. Bundle
What is a commissure?
A white matter pathway that connects identical structures on the right and left sides of the central nervous system.
What kind of information do dorsal nerve roots carry?
Afferent sensory information about the environment to the central nervous system.
What kind of information do ventral nerve roots carry?
Efferent motor signals from the central nervous system to the periphery.
What is the Cauda Equina?
"Horse's Tail"

A collection of nerve roots which continues through the vertebrae after the spinal cord ends (at L1 or L2).
Where in the spinal cord does the sympathetic nervous system arise?
From thoracic and lumbar spinal levels (T1 to L2).
What neurotransmitter does the sympathetic nervous system release onto end organs?
Norepinephrine
Where in the spinal cord does the parasympathetic nervous system arise?
From sacral spinal levels S2 to S4.

However, it also arises from the cranial nerves.
What neurotransmitter does the parasympathetic nervous system release onto end organs?
Acetylcholine
What is the insular cortex?
A region of the cerebral cortex that is buried within the depths of the Sylvian fissure.
What is an operculum?
A "lip."

Frontal operculum - covers the anterior of the insula

Parietal operculum - covers the posterior of the insula
How many cell layers does the neocortex have?
6
Layer I of the neocortex contains...
Mainly dendrites of neurons from deeper layers and axons.
Layers II and III of the neocortex contain...
Cortical to cortical connections
Layer IV of the neocortex contains...
Inputs from the thalamus
Layer V of the neocortex contains...
Outputs to subcortical structures other than the thalamus, such as the brainstem, spinal cord, and basal ganglia.
Layer VI of the neocortex contains...
Outputs primarily to the thalamus.
What is the most important motor pathway in humans?
Corticospinal tract
What is the path of the corticospinal tract?
1. Starts primarily in the primary motor cortex
2. ~85% cross over at the pyramidal decussation, which occurs at the junction between the medulla and spinal cord

See Blumenfeld (p. 33)
What are upper motor neurons (UMN)?
Motor neurons that project from the cortex down to the spinal cord or brainstem.
What are lower motor neurons (LMN)?
Motor neurons that project from the anterior horn of the central gray matter of teh spinal cord out the central nervous system via the anterior spinal roots or via the cranial nerves to finally reach muscle cells in the periphery.
Describe the cerebellar feedback circuit or system
- It receives major inputs from the motor cortex.
- It also receives significant inputs from teh brainstem and spinal cord.
- It then projects information back to the motor cortex via the thalamus
Does the cerebellum have direct connections to the lower motor neurons?
No
Describe the basal ganglia feedback circuit or sytem
- It receives major inputs from the motor cotex.
- It then projects back to the motor cortex via the thalamus.
What is the purpose of the cerebellar and basal ganglia circuits?
It refines the output of the motor system.

They act by modulating the output of the corticospinal and other descending motor systems.
What will lesions to the cerebellum lead to?
1. Disorders of coordination
2. Disorders of balance
3. Ataxia
What will lesions of the basal ganglia produce?
1. Hypokinetic movement disorders, in which movements are slow and rigid - e.g., Parkinsonism

2. Hyperkinetic movement disorders, which are characterized by dancelike involuntary movements - e.g., Huntington's disease
What are the 2 main somatosensory pathways?
1. Posterior column pathways

2. Anterolateral pathways
What kind of sensory information do the posterior column pathways contain?
1. Proprioception

2. Vibration sense

3. Fine, discriminative touch
What kind of sensory information do the anterolateral pathways contain?
1. Pain

2. Temperature

3. Crude touch
Are the somatosensory pathways mutually exclusive or are touch sensations carried by both pathways?
They are carried by both pathways, which means that isolated lesions will not necessarily eliminate certain touch sensations.
What is the dorsal root ganglia?
It is where the primary sensory neuron is located. It is outside of the central nervous system (see Blumenfeld p. 35).
What is unique about the primary sensory neurons, with respect to their axons?
They have bifurcating axons, which means that one long process extends to the periphery, while the other one extends to the spinal cord.
Describe the course of the posterior column sensory pathway
1. Primary sensory neuron axons carry information via the dorsal root through the ipsilateral white matter dorsal (posterior) columns.

2. The axons travel all the way to the dorsal (posterior)column nuclei in the medulla.

3. Here they synapse onto secondary sensory neurons, which send out axons that cross over to the other side of the medulla.

4. These axons then ascend on the contralateral side and synapse in the thalamus.

5. From there, neurons project to the primary somatosensory cortex (precentral gyrus).
Describe the course of the anterolateral or spinothalamic sensory pathway
1. Primary sensory neurons enter the spinal cord via the dorsal roots.

2. They immediately synapse in teh gray matter of the spinal cord.

3. Axons from the secondary sensory neurons cross over to the other side of the spinal cord and ascend in the anterolateral white matter, forming the spinothalamic tract.

4. Then they synapse in the thalamus.

5. From there, neurons project to the primary somatosensory cortex (precentral gyrus).