Posterior horn of spinal cord

At a glance

English

Posterior horn of spinal cord

Latin (TA2)

Cornu posterius medullae spinalis

System

Brain and spinal cord

Region

Whole body

Side

Single, on the midline

About the posterior horn of spinal cord

The posterior horn, also called the dorsal horn or posterior grey column, is the back wing of the butterfly-shaped grey matter seen in a cross-section of the cord. It runs the full length of the cord as a continuous column. Compared with the anterior horn it is narrow and reaches almost to the surface, ending close to the posterolateral sulcus where the dorsal rootlets enter. It is one of three grey columns, the others being the motor anterior horn and the small lateral horn of the thoracic cord.

Sensory information reaches it from receptors in the skin, muscles, bones and joints. The cell bodies of these first-order neurons lie outside the cord in the dorsal root ganglia, and their central processes enter through the dorsal roots. Some fibres end in the horn at once, some travel briefly in the posterolateral tract capping its tip, and others pass up in the posterior columns. Fine touch, vibration and position sense mostly bypass the horn at first, while pain, temperature and crude touch relay within it.

The horn is organised into six layers, Rexed laminae I to VI, counted from the surface inwards. Lamina I is the thin marginal layer; lamina II is the substantia gelatinosa; laminae III and IV form the nucleus proprius; lamina V is the neck of the horn; and lamina VI, the base, is clearest in the limb enlargements. The other four laminae lie in the intermediate zone and anterior horn.

Because it is the first processing station for pain, the posterior horn is the target of spinal anaesthesia and of many pain-relieving drugs. Shingles reactivates in the dorsal root ganglion and can cause lasting pain through changes in the horn. Damage to the horn produces loss of sensation in the segment it serves.

Function and supply

Function

Receives sensory input from the dorsal roots and relays pain, temperature and touch to ascending tracts and to local reflex circuits, while modulating pain before it reaches the brain.

Blood supply

Chiefly from the paired posterior spinal arteries, with the deeper base also reached by central branches of the anterior spinal artery.