L2 spinal cord segment

At a glance

Level system

L2 segment (spinal cord level)

Lies opposite

T11 to T12 (vertebral levels)Model mapping; varies between people. Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014

Length along the cord

14.9 mmMeasured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range. De Leener et al. 2018; Frostell et al. 2016

Its nerve

The L2 nerve exits between the L2 vertebra and the L3 vertebra, below the L2 vertebra.Betts et al. 2022, §13.4

ISNCSCI key sensory point

Anteromedial thigh, midway between the midpoint of the inguinal ligament and the medial femoral condyleRupp et al. 2021; Kirshblum et al. 2011

ISNCSCI key muscle

Hip flexors: tested by asking the person to flex the hipRupp et al. 2021; Kirshblum et al. 2011

What the sources say

“The posterior horn is responsible for sensory processing.” Betts et al. 2022, §13.2

“The anterior horn sends out motor signals to the skeletal muscles.” Betts et al. 2022, §13.2

Connections to the rest of the body

• Spinal nerves and plexuses

  Lumbar plexus: the front of the thigh

  The lumbar nerves form the lumbar plexus, which supplies the pelvic region and the front of the thigh.

  Betts et al. 2022, §13.4 · Show on the body

• Key muscles (ISNCSCI)

  L2: hip flexors

  In the standard neurological examination after spinal cord injury (ISNCSCI), the strength of the hip flexors is the key test of segment L2. The muscle also receives other segments; the key muscle is a convention for testing, not the whole supply.

  Rupp et al. 2021; Betts et al. 2022, §11.6 · Show on 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

  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

  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

Read more

• Brain–spine interfaces

  A digital bridge around a spinal cord injury. Implants read movement intentions from the cortex and turn them into stimulation of the lumbar cord, so that a person with paralysis can stand and walk under their own control.

• Central pattern generators

  The spinal circuits that can produce the rhythm of stepping on their own. Graham Brown's half-centre idea, where the circuits sit, and why they matter for walking again after spinal cord injury.