The midbrain, also known as the mesencephalon is the part of the brain most responsible for vision, motor control, arousal, temperature regulation, alertness and hearing.

Formation and Orientation

The midbrain is found under the cerebral cortex and above the hindbrain. The mesencephalon is not divided into any other portions of the brain unlike the other two vesicles that stem from the neural tube.

There are four separate lobes on the side of the cerebral aqueduct within the midbrain. These are separated into the superior and the inferior colliculi. The superior colliculus is in charge of optics while the inferior colliculus is in charge of audible information.

Also found on the cerebral aqueduct are the cerebral peduncles. Between the cerebral peduncles are interpeduncular fossa, the trochlear nerve and the oculomotor nerve, which is in charge of eye movement and pupil constriction.


The function of the midbrain is to create a response to sensory information and making sure that the body recognizes input that is received.

Image Caption: This is a section in the transverse plane through the human midbrain at the level of the superior colliculus. The front of the head is near the bottom of the picture. Credit: Wikipedia (CC BY-SA 3.0)