T12 spinal nerve

At a glance

Level system

T12 nerve (named for its spinal cord segment)

Where it leaves the canal

The T12 nerve exits between the T12 vertebra and the L1 vertebra, below the T12 vertebra.Betts et al. 2022, §13.4

Distance down the canal before it exits

66 mmMeasured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range; drawn root, schematic

ISNCSCI key sensory point

Midclavicular line, midpoint of the inguinal ligamentRupp et al. 2021; Kirshblum et al. 2011

Roots, ganglia and nerves are drawn schematically from each segment to its exit; their paths are not traced from imaging.

What the sources say

“For the thoracic and lumbar nerves, each one emerges between the vertebra that has the same designation and the next vertebra in the column.” Betts et al. 2022, §13.4

“All of the spinal nerves are combined sensory and motor axons that separate into two nerve roots.” Betts et al. 2022, §13.4

“The sensory axons enter the spinal cord as the dorsal nerve root.” Betts et al. 2022, §13.4

“The motor fibers, both somatic and autonomic, emerge as the ventral nerve root.” Betts et al. 2022, §13.4

Connections to the rest of the body

• Key sensory points (ISNCSCI)

  Key sensory points: one patch of skin per segment

  The examination tests light touch and pinprick at one key point per segment on each side, from C2 behind the ear to S4–5 beside the anus. The points here were placed on this body by following the standard’s written descriptions from bony landmarks, so they are approximate.

  Rupp et al. 2021; Kirshblum et al. 2011 · Show on the body

• Sympathetic outflow

  Sympathetic outflow: thoracic and upper lumbar cord

  Every sympathetic signal to the body leaves the cord between T1 and L2, from neurons in the lateral horn, and passes through the chain of ganglia beside the vertebral column.

  Wulf and Tom 2023; Betts et al. 2022, §15.1 · Show on the body

• Sympathetic outflow

  Spleen: sympathetic from T4–T12

  Sympathetic neurons for the spleen sit in the lateral horn of segments T4 to T12. A spinal cord injury above these segments cuts them off from the brain's control, though they still work as part of spinal reflexes.

  Wulf and Tom 2023 · Show on the body

• Sympathetic outflow

  Pancreas: sympathetic from T6–L2

  Sympathetic neurons for the pancreas sit in the lateral horn of segments T6 to L2. A spinal cord injury above these segments cuts them off from the brain's control, though they still work as part of spinal reflexes.

  Wulf and Tom 2023 · Show on the body

• Sympathetic outflow

  Liver: sympathetic from T7–T12

  Sympathetic neurons for the liver sit in the lateral horn of segments T7 to T12. A spinal cord injury above these segments cuts them off from the brain's control, though they still work as part of spinal reflexes.

  Wulf and Tom 2023 · Show on the body

• Sympathetic outflow

  Kidneys: sympathetic from T11–L1

  Sympathetic neurons for the kidneys sit in the lateral horn of segments T11 to L1. A spinal cord injury above these segments cuts them off from the brain's control, though they still work as part of spinal reflexes.

  Wulf and Tom 2023 · Show on the body

• Sympathetic outflow

  Bladder and urethra: sympathetic from T11–L2

  Sympathetic neurons for the bladder and urethra sit in the lateral horn of segments T11 to L2. A spinal cord injury above these segments cuts them off from the brain's control, though they still work as part of spinal reflexes.

  Wulf and Tom 2023 · Show on the body