Mesencephalon

Mesencephalon or the midbrain is a portion of the central nervous system associated with vision, hearing, motor control, sleep and wake cycles, alertness, and temperature regulation. It is located within the brainstem and makes up part of the brainstem.

Structure

The mesencephalon is the most rostral part of the brainstem and is located between the diencephalon and the pons. It is composed of the tectum (or corpora quadrigemina), tegmentum, the ventricular mesocoelia (or "iter"), and the cerebral peduncles.

Tectum

The tectum (roof in Latin) comprises the posterior part of the midbrain. It is formed by four rounded eminences, the superior and inferior colliculi.

Tegmentum

The tegmentum is the region located between the ventricular surface and the midbrain substantia nigra. It contains the red nucleus, the periaqueductal gray, and multiple cranial nerve nuclei.

Cerebral Peduncles

The cerebral peduncles are paired structures present on the front side of the midbrain. Each peduncle is made up of a large nerve fiber bundle, the corticospinal tract.

Function

The mesencephalon is involved in functions such as vision, hearing, eye movement, and body movement. The anterior part has the cerebral peduncle, which is a bundle of axons traveling from the cerebral cortex to the pons and contains the motor fibers that give voluntary commands to the skeletal muscles.

Clinical significance

Damage to the midbrain can cause a variety of motor and sensory problems, including Parkinson's, Tourette's, and problems with eye movement and coordination.

See also

• Brain
• Brainstem
• Central nervous system
• Cerebral peduncle
• Diencephalon
• Pons
• Superior colliculus
• Inferior colliculus

Mesencephalon Resources
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