Decussation

Decussation is a term used in biology and medicine to describe a point in the body where structures cross over like the shape of the letter X. The term is derived from the Latin word "decussis" which means "a ten" (as in a Roman ten-piece coin), because the Roman numeral for ten, X, resembles a cross.

Overview

In the context of neuroanatomy, decussation refers to the crossing over of nerve tracts from one side of the body to the other. These crossings typically occur in the brainstem and spinal cord, but can also occur in other parts of the nervous system. The result of this crossing is that the left hemisphere of the brain controls the right side of the body, and vice versa.

Examples of Decussation

There are several examples of decussation in the human body. These include:

• The pyramidal decussation, which occurs in the medulla oblongata. This is where the corticospinal tract crosses over to the opposite side of the body.
• The Decussation of the superior cerebellar peduncles, which occurs in the midbrain. This is where fibers from the cerebellum cross over to the opposite side of the brain.
• The Optic chiasm, where the optic nerves from the two eyes cross over to the opposite side of the brain.

Clinical Significance

Understanding the concept of decussation is important in clinical medicine, as it helps to explain why damage to one side of the brain can result in symptoms on the opposite side of the body. For example, a stroke affecting the left hemisphere of the brain can cause paralysis on the right side of the body, a phenomenon known as hemiplegia.

See Also

• Commissure
• Chiasma
• Contralateral brain

References

Decussation Resources
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