Nucleus proprius
A layer of grey matter in the head of the posterior horn, just deep to the substantia gelatinosa, made up of Rexed laminae III and IV.
At a glance
- English
- Nucleus proprius
- Latin (TA2)
- Nucleus proprius
- System
- Brain and spinal cord
- Region
- Whole body
- Side
- Single, on the midline
About the nucleus proprius
The nucleus proprius is not a compact cluster but a band of cells running the full length of the spinal cord in the posterior horn. In cross-section it lies in the head of the horn, immediately deep to the pale substantia gelatinosa and superficial to the neck of the horn. In Rexed's system of ten grey layers it corresponds to laminae III and IV. Its name, the proper nucleus, simply marks it as the main cell mass of the posterior horn.
Its neurons are larger than the small cells of the substantia gelatinosa and vary in shape. They receive large myelinated fibres from the skin, carrying touch and pressure, and also connections from the superficial layers that bring in pain and temperature. Many of its cells have wide dendrites that reach up into lamina II, so they combine several kinds of input.
Cells of the nucleus proprius send axons in several directions. Some cross in the anterior white commissure and join the spinothalamic tracts, so this layer is one of the first relays on the pathway for pain, temperature and crude touch. Others pass to deeper laminae of the same segment, where they take part in reflexes, or ascend to the posterior column nuclei of the medulla. Further projections reach centres above the cord, such as the thalamus, hypothalamus and midbrain.
This layer and the substantia gelatinosa together form the main site where sensation from the body is first processed and adjusted before reaching the brain. Descending fibres from the brainstem act on these layers to reduce the flow of pain signals, which underlies the pain-relieving action of opioids and the gate control idea of pain.
Function and supply
- Function
- Receives touch, pressure and pain input from the dorsal roots and passes it on through the spinothalamic tracts, the posterior column nuclei of the medulla and higher centres, while also feeding local spinal reflexes.
- Blood supply
- Supplied mostly by the posterior spinal arteries, which serve the posterior horns and posterior columns.
Anthromica
See the nucleus proprius where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
