The portion of brain which is located between the thalams/hypothalamus of the forebrain and pons of hind brain is called the mid brain. Its cavity is very narrow like a canal and it is called cerebral aqueduct/ aqueduct of sylvius or iter which passes through it. The mid brain is divisible into: 1. Cerebral peduncles or crura cerebri: These structures are made up of myelinated neurons that appears like a stalk. They connect the cerebrum with the spinal cord. 2. Corpora quadrigemina: These structures are made up of grey matter forming four lobes globular (round) structures behind aqueduct/at the dorsal portion of the midbrain. Each swelling/lobe is terms as colliculus and collectively called corpora quadrigemina. The upper - superior colliculi are associated with vision and lower - inferior colliculi are with hearing reflex sentres.