L119 Functional Organization of CNS

Question 1

List in detail the components of the central nervous system?

Answer 1

Cerebrum, cerebellum, brain stem (midbrain, pons, medulla), hypothalamus, thalamus, limbic system, basal ganglia and spinal cord

Question 2

Which neuronal components make up gray matter vs white matter?

Answer 2

Gray matter = neuronal bodies (somata) and glia

White matter = axons (myelinated) and glia

Question 3

What is the purpose of a diffusion weighted MRI?

Answer 3

To show the white matter axon tracts and orientation (stripped away gray matter)

Question 4

At which vertical point does the brain axis/dorsal orientation change 90 degrees?

Answer 4

Midway at the top of brainstem, the dorsal component of brain changes from the back of the head to the top of the head.

Question 5

Describe the cerebrum?

Answer 5

Made of two hemispheres (left and right), split by the longitudinal fissure. Ridges (gyri) and grooves (sulci) found throughout surface. Surface layer is the cerebral cortex.

Question 6

1. What does the cerebral cortex do?
2. Name each lobe?
3. Describe the cellular structure?

Answer 6

It is the site of language, emotions, memory, and self-awareness.
Split into Frontal lobe, temporal lobe, parietal lobe, and occipital lobe.
Cortex has a superficial layer of gray matter over a core of white matter. Seven layers in total, each with characteristic neuronal shape and function. Pyrmidal neurons and interneurons. Left and Right hemisphere linked by corpus collosum.

Question 7

What are Brodmann’s areas?

Answer 7

Areas of the brain distinguished by histology and sometimes function. Designed 100ya.

Question 8

How are motor movements fine-tuned?

Answer 8

Cerebellum and Basal Ganglia compare what motor function you intended to do with what you actually did. Does the fine tuning to produce smooth movements.

Cerebellum receives the signals, transmits them to the basal ganglia which produces a ‘motor program’ then sends the signal back to cerebellum.

Damage to Cerebellum manifests as clumsiness.

Question 9

Describe the embryological location as well as components of Basal Ganglia?

Damage/dysfunction/pathology of the basal ganglia can results in which diseases commonly?

Answer 9

Located in the telencephalon.
Consists of caudate, putamen, and globus pallidus.
(caudate + putamen = striatum)

Basal ganglia + the subthalamic nucleus = substantia nigra

Damage to basal ganglia can lead to Parkinson’s disease and Huntington disease.

Question 10

Which part of the brain is the major sensory relay to the cortex?
Describe it’s structure/function.

Answer 10

The thalamus.
Part of the Diencephalon. Located at the core of the brain, bilaterally, within the area of the basal ganglia.

Consists of 12 subnuclei that function to:

1. Relay all sensory information to specific areas of the cortex
2. Relay non-sensory information from basal ganglia to specific areas of cortex
3. Project globally to cortex to influence arousal/sleep

Question 11

Which part of the brain controls homeostasis and the pituitary gland?

Answer 11

Hypothalamus. Located below the thalamus. Part of the Diencephalon. Consists of lateral–>medial–>paraventricular layers.

Controls temperature, blood volume and pressure, O2, ion concentration, pH and blood glucose. AND endocrine function of the pituitary.

Question 12

What are the components and functions of the brain stem?

Answer 12

Located beneath thalamus. Consists of Pons, midbrain and medulla.
Controls facial muscles, sensation from face and head, cardiorespiratory control, AND arousal and sleep/wake cycle.

Question 13

Name all the cranial nerves? What do they generally do?

Answer 13

1. Olfactory
   2.Optic
2. Oculomotor
3. Trochlear
4. Trigeminal
5. Abducens
6. Facial
7. Auditory-vestibulor
8. Glossopharyngeal
9. Vagus
10. Accessory (spinal)
11. Hypoglossal
    Mnemonic: Oh Oh Oh To Touch And Feel (a) Virgin Girl’s Vagina And Hymen

Can be purely motor, sensory, or mixed.
10 of these 12 provide sensory and motor supply to face.

Question 14

Describe structure of the spinal cord?

Answer 14

White matter on the outside with a gray matter core (inverse of the brain). Gray matter resembles an H shape, has dorsal (posterior) horns and ventral (anterior) horns.

Connects to the Medulla and is enclosed in the vertebrae.

Begins at C1 and ends at around L1/L2.

Question 15

Where does the spinal cord change in thickness? Why?

Answer 15

Widens at lower cervical and lumbar regions because it has more gray matter to service the motor/sensory activity of the arms/legs.

Question 16

What makes up a spinal nerve?

Answer 16

Dorsal and Ventral root ganglion combine to form the spinal nerve.

Dorsal Root Ganglion carry sensory information (primary afferent nerves) and contain ganglion outside of the CNS.

Ventral Root Ganglion carry motor information (primary efferent nerves) and contain ganglion within the ventral horn.

Question 17

What makes up a Peripheral Nerve?

Answer 17

Peripheral nerve contains both motor and sensory neurons. Thus, damage will cause both types of symptoms.

Question 18

What is a dermatome?

Answer 18

These are areas of the skin that are innervated by a bilateral pair of dorsal root ganglia

Question 19

What are the ventricles?

Answer 19

Hollow parts of the brain (inner hollow part of neural tube during embryology).

Lateral, Third, and Fourth ventricles are filled with CSF.

Question 20

What is CSF?

Answer 20

Cerebrospinal fluid is an ultrafiltrate of plasma. Created by the vascular choroid plexus in the ventricles. CSF flows out of 4th ventricle.

Provides a buffer for the brain, allows buoying of the brains weight.

Question 21

Where are the meninges? Function?

Answer 21

These are protective connective tissue layers lining the brain. Outtermost layer is the Dura Mater (thickest), then Arachnoid matter (fibrous), then Pia Mater (thinnest).

Subarachnoid space contains CSF fluid. CSF is resorbed by major veins at arachnoid granulations.

Question 22

What are the functions of the Falx and Tentorium?

Answer 22

These are connective tissue layers. The Falx seperates the right and left hemispheres and runs within the longitudinal fissure.
The Tentorium seperates the cerebellum from the occipital lobe.

Question 23

What is the Blood Brain Barrier?

Answer 23

Formed by endothelial cells of capillaries. Very tight junctions, only permitting transport by active transport.
***CSF is different from plasma.