Class 1

Question 1

CNS is composed of….

Answer 1

…encephalon (brain) enclosed within the cranium
AND
medulla spinalis (spinal cord) integrated within the vertebral cana

Question 2

PNS consist of…..

Answer 2

….Series of nerves which connect CNS to various tissues of the body; arranged into 12 pairs of cranial nerves and 31 pairs of spinal nerves

Question 3

Gray matter Vs White matter

Answer 3

Gray matter: numerous cell bodies and relatively free myelinated axons
White matter: Numerous long-range myelinated axons and relatively few cell bodies

Question 4

what are Neurons?

Answer 4

Functional units of the nervous system

Question 5

What are the 2 main properties of neurons?

Answer 5

(1) Excitability - the ability to respond to stimuli

(2) Conductivity - the ability to conduct a signal

Question 6

What are the 2 types of neuron processes?

Answer 6

(1) Dendrites - conduct nerve impulses towards the cel body (approx. 4-200 dendrites per neuron) and ends by a sensory receptor
(2) Axons - carries nerve impulses away from the cell body (generally one per neuron) and ends by a synapse which connects to the next nerve or muscle cell

Question 7

Types of Neurons based on their function?

Answer 7

Afferent sensory neurons (protoneurons)
Efferent motor neurons (motoneurons)
Interneurons (association neurons)

Question 8

Afferent sensory neurons (protoneurons)

Answer 8

Neurons and nerve fibers convey information from sensory receptors in the body to the CNS

- Their cell bodies lie in the ganglia (spinal or cranial) of the PNS
- Their dendrites are connected to the sensory receptors

Question 9

Efferent motor neurons (motoneurons)

Answer 9

Neurons and nerve fibers convey nerve impulses away from the CNS to the effectors (e.g. muscle)

- Their cell bodies lie within the CNS: anterior horn of the spinal cord (5 motor nuclei), and motor nuclei of the cranial 	   nerves
- Their axons are connected to the effectors

Question 10

Interneurons (associated neurons)

Answer 10

Lie within the CNS

Their functions are to carry impulses from sensory neurons to motor neurons, and to process incoming neural information

Question 11

Boundaries of the medulla spinalis (spinal cord)

Answer 11

• Occupies the upper 2/3rds of the vertebral canal
• extends from the level of the upper border of the atlas to the lower border of the first, or the upper border of the second
  lumbar vertebra

Question 12

Above the Atlas……

Answer 12

…..the spinal cord is continuous with the brain

Question 13

Below the upper border of the second lumbar vertebrae…..

Answer 13

….the spinal cord ends in a conical extremity called the conus medullaris, and proceeding cowards from the apex of the conus medullaris is a delicate filament, filum terminale, which provides a connection between the cornus medullaris and the coccyx thus stabilising the entire spinal cord

Question 14

What is the Cauda equina?

Answer 14

Cauda equina (‘horse tail’) is a collection of lumbar and sacral nerve roots distal to the cornus medullaris

Question 15

Average length and weight of the spinal cord?

Answer 15

A.L = 45cm
A.W = 30g