The marginal nucleus of spinal cord, or posteromarginal nucleus, or Substantia Marginalis, Rexed lamina I, is located at the most dorsal aspect of the dorsal horn of the spinal cord

Spinal cord

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...

. The neuron

Neuron

A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

s located here receive input primarily from Lissauer's tract and relay information related to pain

Pain

Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

 and temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

sensation. Pain sensation relayed here cannot be modulated, e.g. pain from burning the skin.