Structures of the Midbrain

STRUCTURES OF THE MIDBRAIN The midbrain is primarily composed of the thalamus, hypothalamus, pituitary, pineal gland, hippocampus, amygdala, and basal ganglia. Thalamus. The thalamus is the meeting point for almost all nerves that connect one part of the brain to another part of the brain, the body to the brain, and the brain to the body. The thalamus, the name of which is derived from the Greek word meaning " inner chamber ;' is the oldest and largest part of the midbrain. A collection of nerve cell nuclei that meet at a central junction point, it is made up of two distinct thalamic centers, one on each side of the midbrain. Think of the thalamus as a switchboard or air traffic control tower that can connect any part of the brain and the body. There is not one signal from the environment that does not pass through the thalamus. The sensory organs (ears, eyes, skin, tongue, nose) send messages to the thalamus, which relays them to their final destination in the neocortex/conscious brain. At the same time, the thalamus can send signals to other areas of the brain so as to alert or inhibit different brain systems. In this way, the thalamus processes sensory information from the external world, identifies and sorts the input into the appropriate category, and transmits this data to the many conscious centers in the cerebral cortex. Depending on the nature of the sensory information or the type of stimulation from the environment, the data is then passed in many different directions throughout the brain (the midbrain, the brain stem, and so on) and body. The thalamus is also the relay system between the neocortex and the brainstem. Thus, this part of the midbrain allows the entire brain to receive a multitude of important data from the external world all at once, so that the brain can readily be introduced to vital information.


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