Midbrain

Midbrain, also called mesencephalon, is the narrow part of the brain that passes through the tentorial notch and connects the forebrain to the hindbrain.

Anatomical subdivision:

Anatomically, the midbrain is divided into two halves, known as cerebral peduncles. Each peduncle is further divided into two parts by a band of gray matter called substantia nigra. The anterior part is called crus cerebri and the posterior part is called tegmentum.

Cerebral aqueduct:

The midbrain has a narrow cavity, known as the cerebral aqueduct. It is a part of the ventricular system of brain and connects the third ventricle to the fourth ventricle.

Tectum:

It is the part of midbrain that lies posterior to the cerebral aqueduct. It contains four small surface swellings; the two superior and two inferior colliculi.

Pineal body:

It is a small glandular structure that lies between the superior colliculi. It is attached by a stalk to the posterior wall of the third ventricle.