spinal nerve numbers

Question 1

how many pairs of spinal nerves exist via the intervertebral foramina (vs. 33 vertebrae)

Answer 1

21 pairs. they are 8C, 12T, 5L, 5S, and 1Cx

Question 2

How do the cervical nerves leave the vertebral column?

Answer 2

they leave above their same numbered vertebra. The exception is the C8 nerve because there is no C8 vertebra. This leaves at C7-T1

Question 3

How do thoracic and lumbar nerves leave the vertebral column?

Answer 3

below their same numbered vertebra

Question 4

what is the second number rule?

Answer 4

the nerve affected by posterolateral disk prolapse is designated by the second number in the disk’s name (disk C5-6 typically impinges on nerve C6). In the cervical region, this is nerve leaving at that level. in lumbar level, this is nerve leaving at the next lower vertebral level.

Question 5

Does second number rule work for thoracic level?

Answer 5

No. only cervical and lumbar.