Question

•Rexed lamina identify the 10 different layers in the gray matter according to size, density, staining properties and connections of neurons.

Answer 1

The central nervous system consist of two kinds of tissues :

• Grey matter and
• White matter

Grey matter refers to unmyelinated neurons. Mostly seen in spinal cord, brain, brain stem, cerebellum.

The grey matter of the spinal cord can be divided into 10 different layers called Rexed lamina. They are defined based on their cellular location. They are:

• Posterior grey column ( I to VI )

1. Rexed lamina I is located at dorsal horn of the spinal cord.They relay information related to pain and temperature.
2. Rexed lamina II is one of the three grey column at the apex of the posterior region of the spinal cord. It helps to manage pain sensation.
3. Rexed lamina III and IV can be found in all over the spinal cord. I t involves in pain and temperature sensation first synapse.
4. Rexed lamina V is located in the neck of dorsal horn. They process sensory afferent stimuli.
5. Rexed lamina VI is located at the base of dorsal horn.It gets input from large diameter fibre muscles and joints and it helps to strech the fibres to transfer the signal to cerebellum.

• Lateral grey column ( VII and X )

1. Rexed lamina VII is found on one of three grey columns of the spinal cord. It contains autonomic motor neurons.
2. Rexed lamina X is surrounding the central canal.

• Anterior grey column ( VIII and IX )

1. Rexed lamina VIII consist of motor interneurons helps in connection between motor neurons, sensory neurons and central nervous system.
2. Rexed lamina IX is seen in anterior horn of spinal cord. It helps in muscular contraction.