The midbrain (also called the mesencephalon) surrounds the cerebral Aqueduct and consists of two major parts the Tectum and the Tegmentum.
Tectum
The Tectum (roof) is located in the dorsal portion of the midbrain. Its principal structures are the superior colliculi and inferior colliculi, which appears as four bumps on the surface of the brain stem. The brain stem includes the diencephalons, midbrain and hindbrain, and it is so called because it looks just like that ___a stem. The inferior colliculi are a part of auditory system. The superior colliculi are part of the Visual System. In mammals there are involved primarily in visual reflexes and reactions to moving stimuli.
Te Tegmentum (covering) consists of the portion of the midbrain beneath the Tectum. It includes the rostral end of the reticular formation, several nuclei that control eye movements, the periaqueductal gray matter, the Red nucleus, the Substantia nigra and the ventral tegmental area.
The Reticular formation is a structure consisting of many individual nuclei. It is also characterized by a diffuse, interconnected network of neurons with complex dendritic and axonal processes. (Indeed reticular means "little net"; early anatomists were struck by the netlike appearance of the reticular formation).
The Periaqueductal Gray Matter is so called because it consists mostly of cell bodies of neurons ("gray matter" as contrasted with the "white matter" of axon bundles) that surrounds cerebral aqueduct as it travels from the third to the fourth ventricle. The periaqueductal gray matter contains neural circuits that control sequences of movements seen in some species-typical behaviors, such as fighting and mating.
The Red Nucleus and Substantia Nigra (black substance) are important components of the Motor System. A bundle of axons that arises from the red nucleus makes up one of the two major Fiber systems that bring motor information from the cerebral cortex and cerebellum to the spinal cord.
I mentioned earlier that Parkinson's disease is caused by Degeneration of certain neurons located in the midbrain that send axons to the Caudate nucleus and the Putamen.
These neurons are located in the substantia nigra.
2 comments:
This is great stuff! Very honest and practical. I really enjoyed this post.
https://blog.mindvalley.com/midbrain
Amazing post.Thank you very much for this important post.
https://blog.mindvalley.com/midbrain-function
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