Where do spinal nerves leave the vertebral canal?

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Diagram comparing action potential conduction in myelinated and unmyelinated axons, showing a neuron with labeled cell body, myelin sheath, nodes of Ranvier, and the flow of electrical signals along each type of axon. — nervous system In a myelinated axon, the myelin sheath prevents the local current (small black arrows) from flowing across the membrane. This forces the current to travel down the nerve fibre to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels. Upon stimulation, these ion channels propagate the action potential (large green arrows) to the next node. Thus, the action potential jumps along the fibre as it is regenerated at each node, a process called saltatory conduction. In an unmyelinated axon, the action potential is propagated along the entire membrane, fading as it diffuses back through the membrane to the original depolarized region.

Spinal nerves exit the vertebral canal through openings known as intervertebral foramina. These openings are located on the left and right sides of the spinal column between adjacent vertebrae.123

Regarding the specific exit points:
* The first spinal nerve (C1) exits between the skull and the first cervical vertebra.2
* Spinal nerves C1 through C7 exit above their correspondingly numbered vertebrae.2
* Spinal nerve C8 exits between the 7th cervical and first thoracic vertebrae.2
* Beginning with T1, all subsequent spinal nerves exit below their corresponding vertebrae.2

In the lower regions of the spine, the lumbar and sacral nerve roots descend for a distance within the subarachnoid space before reaching their respective foramina, forming a collection of nerve roots known as the cauda equina.1