is generally described as having three divisions. The forebrain is composed of the cerebrum, the thalamus, and the hypothalamus. The midbrain is a short, constricted portion connecting the forebrain to the hindbrain, containing the corpora quadrigemina and Aqueduct of Sylvius. The hindbrain is composed of the pons, medulla oblongata, and cerebellum. The brain stem is defined as the midbrain, pons, and medulla oblongata.