Ans: Our spinal cord is a vital hub in our body that processes and relays information and connects our brain to the rest of the body. Grey matter in the spinal cord, based on its function, can be classified in three different ways:​1. Four Main Columnsa. Dorsal horn (posterior horn) - These have neurons that receive somatosensory signals of the body and then send them to the brain through an ascending pathway.b. Ventral horn (anterior horn) - This has mainly motor neurons.c. Intermediate column - These along with lateral horn supply neurons to pelvic and visceral organs.d. Lateral horn - This column works similar to the intermediate column.2. Six different Nucleia. Marginal zone - This is situated at the tip of the dorsal horn and relays temperature and pain stimuli to the brain.b. Susbtantia gelatinosa - This is present at the top of the dorsal horn and relays pain, temperature, and light touch sensation to the brain.c. Nucleus proprius - Situated at the neck of the dorsal horn, nucleus proprius relays temperature and mechanical sensations to the brain.d. Dorsal nucleus of Clarke - DNC is responsible for relaying unconscious proprioceptive sensation to the brain. These are found only in two spinal segments which are L3 and C8.e. Intermediolateral nucleus (IMN) - It is present in the lateral horn as well as the intermedial column. Sensory information from the viscera is conveyed to the brain through IMN.f. Medial and lateral motor neurons (MNs) - They are inside the ventral horn and are made up of motor neurons. They innervate skeletal and visceral muscles.3. Ten Rexed Laminae These are layers inside the spinal cord which have cells grouped as per their structure and function and not just based on location.a. Lamina I - They correspond to the marginal zone and cells in this lamina respond to thermal or noxious stimuli.b. Lamina II - They correspond to the substantia gelatinosa and cells in this lamina respond to noxious or non-noxious stimuli. They modulate sensory input and help the brain in interpreting whether incoming signals are painful or not.c. Lamina III - They partially correspond to the nuclear proprius and are involved in the sensation of light touch and proprioception.d. Lamina IV - These cells connect with the cells in lamina II and partially correspond to the nuclear proprius. They relay and process non-anxious sensory information.e. Lamina V - It receives the descending information from the brain and relays sensory information including potentially painful ones (nociceptive) to the brain.f. Lamina VI - It has many tiny interneurons that are involved in spinal reflexes. g. Lamina VII - This is a large zone that receives information from lamina II to lamina VI. Its job is to relay information to the viscera. DNC is part of Lamina VII. It also produces cells that are involved in the autonomic system.h. Lamina VIII - Cells in this layer modulate motor output to skeletal muscle.i. Lamina IX - It is a distinct group of motor neurons that provide neurons to skeletal muscle.j. Lamina X - This layer crosses over from one side of the spinal cord to another.