<unk>  <unk> ; also called the "central<unk> ") is the midbrain grey matter that is located around the cerebral aqueduct within the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour. The ascending pain and temperature fibers of the spinothalamic tract also send information to the<unk>  via the spinomesencephalic tract. The spinomesencephalic tract is so-named because the fibers originate in the spine and terminate in the mesencephalon, another name for the midbrain, which is the part of the brain in which the<unk>  resides.
Periaqueductal gray
Ventral tegmentum
Lateral horn
Frontal lobe
Cerebral crus
Inferior cerebellar peduncle
Column of Clarke
Cerebellar vermis