Brain-stem is a stem-like part of the brain that connects the cerebrum and the spinal cord. It usually includes the medulla oblongata, pons, and mid-brain. A pair of ten cranial nerves comes from the brain-stem. The parts of the brain-stem work together to control the movements in the body.
The mid-brain is also known as mesencephalon. It is the topmost part of the brain-stem, located between fore-brain and hind-brain. It is a junction through which the nerves from the fore-brain pass towards the hind-brain (medulla and pons). The top of the mid-brain houses the sight and hearing reflex centres, through which specific signals are responded. The mid-brain also controls certain functions of the eye such as movement and size of the pupils.
The hind-brain is also known as rhombencephalon. It is located below the mid-brain, made up of the pons, medulla oblongata and cerebellum. The cerebellum is the largest part of the hind-brain. One of the main functions of the hind-brain is to control breathing and coordination between muscles. It also helps in the major and complex body movements (arms and legs).
Pons is a large body of transverse nerve fibres. The nerve fibres of pons are the connecting mode between the brain and the cerebellum. Pons in association with the cerebellum helps maintain balance in the body. Individually, pons affects the respiratory process and the breathing.
Medulla oblongata is the lowest portion of the brain-stem. It accommodates several nuclei and cell bodies of cranial nerves. In medulla, the grey matter is inside and the white matter is exposed on the surface. Its main function is to control several functions such as breathing, heart beat rate (cardiac functions), blood pressure and peristaltic movements of the alimentary canal.
Cerebellum is the most important part of the hind-brain, located at the base of the brain. Cerebellum is principally connected with the cerebral hemisphere and the brain-stem. It is connected with the sight reflex centres that lie in the mid-brain. The main function of the cerebellum is to coordinate muscular movements such as walking, dancing, riding a bicycle, etc. It also helps maintain posture and balance of body.