Somatic Nervous System

Question 1

What are the structural divisions in the nervous system?

Answer 1

• CNS (brain & spinal cord)
• PNS (12 cranial & spinal nerves)

Question 2

How many pairs of spinal nerves are there?

Answer 2

31

Question 3

How many regions is there?

Answer 3

5 (named after associated vertebrae)

Question 4

Where does the C1 spinal nerve exit?

Answer 4

Between skull and atlas

Question 5

What is the fibre distribution in spinal nerves?

Answer 5

• Sensory/afferent
• Motor/efferent

Question 6

What is the process for when motor fibres don’t synapse?

Answer 6

CNS —> Skeletal muscle

Question 7

What is the process for when motor fibres synapse?

Answer 7

CNS -(presynaptic)-> Ganglion -(postsynaptic)-> smooth muscle, cardiac muscle, glands

Question 8

What is a dermatome?

Answer 8

Area of skin supplied by a single spinal nerve

Question 9

What is a neuron?

Answer 9

The functional unit of the nervous system

Question 10

What are the parts of a neuron?

Answer 10

• Cell body
• Dendrites
• Axon

Question 11

What are the major types of neuron?

Answer 11

• Bipolar
• Multipolar
• Pseudounipolar

Question 12

What are the 4 types of neurological cells found in the CNS?

Answer 12

• Astrocytes
• Microglial cells
• Ependymal cells
• Oligodendrocytes

Question 13

What is myelin?

Answer 13

Lipid and protein substance that is secreted by Schwann cells (glial cell) around some axons

Question 14

What is a myotome?

Answer 14

Part of muscle supplied by a single spinal nerve

Question 15

What is the clinical relevance of dermatomes/myotomes?

Answer 15

Useful to test motor or sensory loss of one or more spinal nerves/segments by testing joint movements or an area of skin in neurological disorders

Question 16

What level is the nipples and belly button?

Answer 16

T4 - nipples
T10 - belly button

Question 17

What is the function of the somatic motor fibres?

Answer 17

Regulates voluntary control of body movements via skeletal muscles

Question 18

What is the function of somatic sensory fibres?

Answer 18

Transmits general sensation (pain, touch, temperature, proprioception etc.) to the CNS

Question 19

If the dorsal root is damaged, what function is lost?

Answer 19

Sensory

Question 20

If ventral root is damaged, what function is lost?

Answer 20

Motor

Question 21

If the spinal nerve is damaged, what function is lost?

Answer 21

Both motor and sensory

Question 22

If the ventral ramus is damaged, what function is lost?

Answer 22

Motor and sensory loss of anterolateral trunk and limbs

Question 23

If the dorsal ramus is damaged, what function is lost?

Answer 23

Motor and sensory loss of the back

Question 24

Where does the spinal nerve exit through?

Answer 24

The intervertebral foramen

Question 25

What is a somatic reflex arc?

Answer 25

• sensory detection (stimulus)
• interpretation of sensory input in the CNS
• motor response (action)

Question 26

How many pairs of cranial nerves are there?

Answer 26

12

Question 27

Where do upper and lower motor neurons synapse?

Answer 27

Anterior horn

Question 28

What does damage to lower motor neuron cell bodies or their peripheral axons result in?

Answer 28

Paralysis (loss of movement) or weakness of the affected muscles