Organisation Of The Nervous System

Question 1

What are the basic divisions of the nervous system?

Answer 1

CNS (Central Nervous System): Brain and spinal cord.

• PNS (Peripheral Nervous System): Motor and sensory neurons.

Question 2

What are the sub-divisions of the autonomic nervous system?

Answer 2

Parasympathetic: Rest and digest (e.g., constricts airways, slows heartbeat).

• Sympathetic: Fight or flight (e.g., dilates pupils, increases heartbeat).

Question 3

What are the differences between motor and sensory fibers?

Answer 3

Motor fibers (GVEs): General visceral efferents.

• Sensory fibers (GVAs): General visceral afferents.

Question 4

What are the anatomical terms for direction?

Answer 4

Dorsal (posterior): Top end.

• Ventral: Belly end.

• Anterior (rostral): Head.

• Posterior (caudal): Feet.

Question 5

What are the three planes used in brain imaging?

Answer 5

Coronal: Cuts facing the front.

• Sagittal: Cuts from the front, midline.

• Horizontal: Flat sideways cut.

Question 6

What are the functions of the different brain lobes?

Answer 6

Temporal lobe: Memory, language.

• Occipital lobe: Vision.

• Parietal lobe: Sensory processing, arithmetic, spelling.

• Frontal lobe: Executive functions, emotion, behavior, personality, planning, thinking.

Question 7

How is the spinal cord organized?

Answer 7

• The spinal cord is housed in the vertebral canal.

• 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).

• The spinal cord is shorter than the vertebral column (ends between L1/2).

• The first spinal nerve emerges between the skull and the first cranial vertebra

Question 8

What is the difference between grey and white matter in the spinal cord?

Answer 8

• Grey matter: Neuronal cell bodies.

• White matter: Myelinated axons

Question 9

What is the surface anatomy of the cerebrum?

Answer 9

Gyri: Ridges on the brain surface.

• Sulci: Shallow grooves.

• Fissures: Deep grooves.

Question 10

What are the regions of the brain?

Answer 10

Forebrain: Cerebrum, hypothalamus.

• Midbrain: Top bit just over hindbrain.

• Hindbrain: Pons, cerebellum, medulla oblongata.

• Brainstem: Midbrain + Pons + Medulla oblongata.

Question 11

Why is the risk of injury lower when performing a lumbar puncture at L3/4?

Answer 11

L3/4 lumbar puncture: The spinal cord ends between L1/2, so a puncture at L3/4 avoids the spinal cord and the risk of injury is reduced.

Question 12

What is the cauda equina?

Answer 12

Cauda equina: A bundle of spinal nerves and nerve rootlets at the end of the spinal cord, resembling a horse’s tail.

Question 13

What is the composition of spinal nerves?

Answer 13

Spinal nerves are mixed: They contain both motor and sensory fibers.

Question 14

Describe the pathway of a sensory signal through the spinal cord.

Answer 14

Sensory signal pathway:

1. Sensory neuron.
2. Dorsal root.
3. Interneuron.
4. Motor neuron.
5. Muscle (response).

Question 15

How do spinal nerves connect to the spinal cord?

Answer 15

• Spinal nerves: Enter and exit the spinal cord as a collection of nerve rootlets.

• Spinal cord segmentation: The spinal cord is segmented, and nerves are associated with these segments.

Question 16

What is the function of the filum terminale?

Answer 16

Filum terminale: A structure that anchors the spinal cord to the coccyx, preventing movement.

Question 17

What is the structure and function of the ventricular system in the brain and spinal cord?

Answer 17

Ventricular system: Includes four ventricles and the central canal.

• Function: Filled with cerebrospinal fluid (CSF), which cushions and nourishes the brain and spinal cord.

Question 18

What is the pathway of cerebrospinal fluid (CSF) in the brain and spinal cord?

Answer 18

Central canal: CSF flows down through the central canal of the spinal cord.

• Interventricular foramen: CSF flows into the cerebral aqueduct.

Question 19

What is the role of the choroid plexus in CSF production?

Answer 19

Choroid plexus: Muscle-like tissue in all ventricles that produces CSF.

• Production: CSF is continuously produced by the choroid plexus epithelium (ependymal cells), which is highly vascularized.

Question 20

What are the main functions of cerebrospinal fluid (CSF)?

Answer 20

Buoyancy (supports the brain).

2. Protection (cushions the brain and spinal cord).
3. Removal of waste products.
4. Provides growth and signaling factors.

Question 21

What is hydrocephalus and how does it occur?

Answer 21

Hydrocephalus: Condition where the CSF pathway is blocked, preventing its reabsorption into the venous bloodstream.

• Result: Fluid builds up, causing expansion of the head.

Question 22

Where is CSF released into after production?

Answer 22

Subarachnoid space: CSF is released into the space between the first and second meninges (the subarachnoid space).

Question 23

What are the three layers of meninges surrounding the CNS?

Answer 23

mater (inner layer):

• Protects the CNS.

• Allows blood vessels to enter the CNS.

• Impermeable to contain CSF.

2. Arachnoid mater:

• Cobweb-like membrane forming the upper limits of the subarachnoid space.

• Protects the CNS and is associated with the dura mater.

3. Dura mater (outer layer):

• Toughest layer protecting the brain and spinal cord.

• In the skull, it forms a double layer that separates to create sinuses carrying venous blood.

• Firmly attached to the brain but loosely attached to the spinal cord.

Question 24

What is the difference between CNS and PNS neurons?

Answer 24

CNS neuron: Entirely within the brain or spinal cord.

• PNS neuron: Projects outside the CNS.