The midbrain is one of the three divisions of the brainstem. It contains a long list of tracts, nuclei, and other structures that are all important to healthy brain function. In this video, I discuss some of the most prominent anatomical features of the midbrain along with some of their putative functions.

TRANSCRIPT:

Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or less. In this installment I will discuss the midbrain.

The midbrain is one of the three divisions of the brainstem.

At the level of the midbrain, the fourth ventricle has narrowed to form the cerebral aqueduct, which connects the third and fourth ventricles.

The region of midbrain behind the cerebral aqueduct is called the tectum. The area in front of the cerebral aqueduct is called the tegmentum. The anterolateral portion is made up of two structures called the basis pedunculi.

The tectum primarily consists of the superior and inferior colliculi—clusters of neurons that together form 4 bumps on the posterior surface of the brainstem. The superior colliculi are thought to be involved with directing behavioral responses toward stimuli in the environment, while the inferior colliculi are known for their role in auditory processing.

The tegmentum contains a variety of ascending and descending tracts, like the medial lemniscus and anterolateral tracts. It also contains fibers from the superior cerebellar peduncles, the main output pathway of the cerebellem, and the red nucleus—a nucleus thought to play a role in motor coordination. The tegmentum contains nuclei for cranial nerves III and IV as well as neurons that are part of the raphe nuclei—the major serotonin producing neurons in the brain, and the ventral tegmental area—one of the largest collections of dopamine-producing neurons in the brain.

The basis pedunculi include the crura cerebri—two large bundles of axons that contain fibers from motor pathways like the corticospinal and corticoblulbar tracts. The basis pedunculi also include the substantia nigra, which is another major dopamine-producing structure in the brain. Finally, the area surrounding the cerebral aqueduct is called the periaqueductal gray. The periaqueductal gray is known for its role in pain inhibition.

References:

Haines DE. Fundamental Neuroscience for Basic and Clinical Applications. 4th ed. Philadelphia, PA: Elsevier; 2013.

Vanderah TW, Gould DJ. Nolte’s The Human Brain. 7th ed. Philadelphia, PA: Elsevier; 2016.

 

Channel: Neuroscientifically Challenged
Categories: Neuroscientifically Challenged,Videos
Video Views: 1,055 views
Original Publish Date: Published on Dec 30, 2017
Source URL: https://www.youtube.com/watch?v=NsWukc8G6wE&index=62&list=PLNZqyJnsvdMqFNFyHvMFrFnlXLosnwwB_

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