The Spinal Nerves

Question 1

How many spinal nerve pairs are there in total?

Answer 1

31 pairs

Question 2

How many pairs of cervical nerves are there?

Answer 2

8

Question 3

How many pairs of thoracic nerves are there?

Answer 3

12

Question 4

How many pairs of lumbar nerves are there?

Answer 4

5

Question 5

How many pairs of sacral nerves are there?

Answer 5

5

Question 6

How many pairs of coccygeal nerves are there?

Answer 6

1

Question 7

Describe the pathway of sensory fibres from the spinal cord to body innervation?

At what point do they unite with motor fibres?

Answer 7

Posterior horn - posterior rootlets - posterior root - dorsal root ganglion - mixed spinal nerve - rami

They unite with motor fibres in the mixed spinal nerve

Question 8

Describe the pathway of motor fibres from the spinal cord to the body innervation?

At what point do they unite with sensory fibres?

Answer 8

Anterior horn - anterior rootlets - anterior roots - mixed spinal nerve - rami

They unite with sensory fibres in the mixed spinal nerve

Question 9

What type of fibres can be found in the anterior and posterior rami?

Answer 9

Both sensory and motor

Question 10

The anterior rami of cervical spinal nerves 3, 4 & 5 form what?

Answer 10

Phrenic nerves

Question 11

Where do Phrenic nerves supply somatic motor innervation to?

Answer 11

The diaphragm

Question 12

Where do Phrenic nerves supply sensory innervation to?

Answer 12

• Mediastinal parietal pleura
• Fibrous pericardium
• Diaphragmatic parietal pleura
• Diaphragmatic parietal peritoneum

Question 13

Why can pain from the diaphragm be referred to the shoulder?

Answer 13

C3, 4 and 5 of the Phrenic nerve supply the parietal peritoneum that lines the surface of the diaphragm

Supraclavicular nerves (C3, 4) supply the dermatomes over the shoulder

Both the supraclavicular and phrenic nerves enter the spinal cord at the same level and can be confused