The periaqueductal gray (PAG) is a region of gray matter found in the midbrain. The PAG environs the cerebral aqueduct and forms a column in the brainstem, measuring around 14 millimetres in length. Although there is no visible division in PAG, researchers have divided it into four columns according to their connectivity and functions; the dorsomedial, dorsolateral, lateral, and ventrolateral columns. Although the functions of FAG are multifaceted and not fully comprehended, its association with the sensation of pain is established. It plays an important role in pain transmission; it transmits the pain signal to the cortex. FAG is recognized as a vital region for pain inhibition.