There are many functions of the midbrain, including body temperature regulation, motor control, and sleep cycles. Additionally, the midbrain influences hearing, vision, and arousal. This vital region is responsible for controlling all of the responses related to sensory information and regulating the body's actions to those responses. For example, if the hand experiences a sharp pain, the midbrain tells the brain that the hand needs to pull back.
The midbrain region is part of the central nervous system. It is located near the center of the brain, under the cerebral cortex and on top of the hindbrain region. This region joins the spinal cord and the brain together and is commonly referred to as part of the brainstem primarily due to its location.
Functions of the midbrain are achieved through the cerebral cortex, cerebellum, and substantia nigra. Input is collected from the environment and sent to the cerebral cortex. The substantia nigra uses input sent from the cerebral cortex to regulate voluntary movements and moods. A path, called the rubrospinal tract, runs from the cerebellum to the bottom motor centers of the brain and sends input as a route for voluntary movement signals.
Due to the functions of the midbrain, it is classified as the most advanced of the regions of the brain. The midbrain itself, also known as the mesencephalon, is divided into sub-sections. Forming a dorsal covering of the midbrain, the tectum regulates auditory and visual stimuli and responses. A bottom section, called the tegmentum, handles motor control, awareness, and autonomic responses. Another section, also part of the basal ganglia, is the substantia nigra which controls and regulates dopamine production and the input and output of the basal ganglia.
There are four divisions of the tectum, known as the corpora quadrigemina. These divisions are called colliculi and are the main sections that control sensory information. Two inferior colliculi handle the auditory information and are located under the superior colliculi. The two superior colliculi handle the visual information and can be found under the thalamus. Together, these four divisions provide collective functions of the midbrain.
Extending from the cerebral aqueduct to the substantia nigra, the tegmentum contains a crucial part called the red nucleus. This specific part regulates the coordination of movements, both simple and complex. The oculomotor nerve that is present in this area is responsible for eye movements and constriction of the pupils.