The Forebrain, also called procencephalon, is the region of the developing vertebrate brain as well as the largest part of the brain. As seen in the picture, the forebrain is in the top part of the cerebrum from the front all the way back. This region includes the telencephalon, containing the cerebral hemispheres, and then the diencephalon under them. The diencephalon contains thalamus (organization of sensory information), hypothalamus (endocrine system and thermoregulation), epithalamus (secretion of melatonin, regulation of motor pathways, and emotions) and subthalamus (correlation center for optic and vestibular impulses).
The midbrain is the region of the brain that contains cranial nerves that stimulate the muscles controlling eye movement, lens shape, and pupil diameter. The midbrain is located in between the forebrain and the hindbrain. The midbrain is made up of the tectum and the tegmentum. Tectum is the latin word for roof. The tectum is contrasted with the tegmentum and responsible for auditory and visual reflexes. Tegmentum is the latin word for covering. The tegmentum is where several cranial nerve (CN) nuclei is located.
Located near the rear and lower portion of the human brain the hindbrain, also known as the rhombencephalon, is responsible for body functions such as respiration and heart rate. The hind brain is made up of the brain stem and the
cerebellum. The brain stem is very important because it controls significant functions including breathing and swallowing. The brain stem also connects the brain to the spinal cord and is made up of the medulla, reticular formation,
and pons. The cerebellum plays a role in physical activity.