Human anatomy > Central Nervous System > Mesencephalon


The brain of a developing animal is formed from the neural tube which will later turn into 3 vesicles: forebrain, midbrain and hindbrain. The middle vesicle mentioned beforehand is the so-called mesencephalon. It is considered to be a part of the brain stem in mature human brains, and becomes among the less differentiated ones.

Mesencephalon is composed of two regions: the tectum (roof), and the tegmentum (covering). Within the mesencephalon is the quadrigemina. It deals with the reflexes of the auditory and visual stimuli, and also with the highly specialized nuclei responsible for the posturing and the motor abilities of the body. The mesencephalon also houses the cerebral peduncles, and is comprised with bundle of nerve fibers.

The nuclei which is responsible for several autonomic functions, together with its corresponding tracts is located within the system of the brain. This section of the brain is vital, because it is attached to the spinal cord. The midbrain, the pons and the medulla oblongata are also found there.

What is Inside the Mesencephalon?

The mesencephalon, or the midbrain has these parts inside it: corpora quadrigemina, red nucleus, the cerebral peduncles and the substantia nigra. The corpora quadrigemina houses four segments- elevated and spherical, and these are found in the midbrain’s posterior part. There are also two upper eminences, called the superior colliculi.

On the inferior colliculi lies another two lower eminences which deals with reflexes for the auditory stimulation. There are two  cylindrical structures located there- those are the cerebral peduncles. These peduncles then create connection for the cerebrum and other parts of the brain.

Meanwhile, the red nucleus is located between the cerebral aqueduct and the cerebral peduncle. It could be found deep in the midbrain. The red nucleus unites with the cerebellum and the cerebral hemispheres so that it will effectively regulate the needed coordination for a human’s posture and motor skills. It absorbs blood rich in oxygen, as well as an iron-rich pigment, thus making it red.

Another part inside the red nucleus is the substantia nigra. This is responsible in inhibiting involuntary movements in the body.

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