Organisation of the Central Nervous System

Question 1

What structure connects the two hemispheres of the brain?

Answer 1

Corpus Callosum

• bendy bit of white matter
• constant conversation between two hemispheres

Question 2

What area is under the corpus callosum

Answer 2

Diencephalon

• consists of thalamus and hypothalamus

Question 3

Functions of the Cerebellum

Answer 3

Motor Function

• not initiation but coordination
• important for learning motor skills e.g. playing the piano

Question 4

Functions of the Brain Stem?

Answer 4

• Contains nuclei which controls vital functions:
• respiratory centre + cardiac centre
• ascending/descending pathways go through the brain stem
• Cranial nerves attached to the brain stem providing sensory + motor innervation

Question 5

Functions of the Diencephalon?

Answer 5

Thalamus - higher areas of diencephalon - relay station between cerebral cortex + other parts of CNS

Hypothalamus - inferior to the thalamus, important in coordinating homeostasis

Question 6

Functions of the Cerebral Cortex

Answer 6

• Many nuclei
• one of them is the basal ganglion
• Basal Ganglia = group of nuclei which produce movement pattern and work with the motor cortex

Question 7

Describe development of the brain?

Answer 7

First develops into 3 parts:

• forebrain
• midbrain
• hindbrain

Forebrain - divides into: cerebral hemispheres + diencephalon

Midbrain - stays same

Hindbrain - pons, medulla, cerebellum

Question 8

Describe the Cortex ?

Answer 8

Left side of the Left Hemisphere. 2 Types:

• Primary Cortical Areas
• Association Cortex

Question 9

Describe the Primary Motor Cortex?

Answer 9

• axons travel down thedescendingpathway to stimulate motor neurons in the spinal cord
• somatotopic arrangement - upside down body
• contralateral arrangement

Question 10

Describe Primary Somatosensory Cortex?

Answer 10

• adjacent to primary motor cortex

- receives general sensory information coming from body

Question 11

Describe Primary Auditory Cortex?

Answer 11

• first to receive information from ears

Question 12

Describe Primary Visual Cortex?

Answer 12

first to receive info from the retina

Question 13

What is the Association Cortex?

Answer 13

Much higher functions take place

- learning, thinking, percep

Question 14

What is Wernicke’s Area?

Answer 14

Important for understanding language

Question 15

What is Broca’s Area?

Answer 15

Important for speech

Question 16

Describe the Ventricular System?

Answer 16

Lateral Ventricles

• 2 large C shaped ventricles with a spur at back
• lateral ventricles in each hemisphere

3rd Ventricle

• single midline ventricle
• middle of the diencephalon

Cerebral Aqueduct
- base of third ventricle narrows to form a fine channel

4th Ventricle
- tent shaped
- pons and medulla is in front
-

Central Canal
- lower part of the medulla the 4th ventricle which narrows and goes down into the spinal cord

Question 17

What is Cerebrospinal Fluid?

Answer 17

• Produced by the Choroid Plexus (ependymal cell) found in the ventricles
• Filters the blood - removes cells and then secretes
• circulates through ventricular system –> 4th Ventricle
• 4th ventricle has holes so CSF can exit
• circulates in the sub-arachnoid space between the meninges
• reabsorbed into the venous system by Arachnoid Villi

Question 18

Describe the Layers of the Meninges?

Answer 18

• Dura, Arachnoid, Pia Mater
• between arachnoid and the pia have the sub-arachnoid space where CSF can circulate
• venous sinuses over the surface of the brain
• out-pockets of the arachnoid membrane push through the walls of the venous sinuses for CSF reabsorption - ARACHNOID VILLI
• blockage –> CSF buildup = hydrocephalus