Pyramidal tract

Pyramidal tract is a part of the nervous system that is involved in the control of voluntary movements. It is named for its pyramid-like shape in the medulla oblongata, where the majority of its neurons originate. The pyramidal tract is divided into two main parts: the corticospinal tract, which controls movements of the body, and the corticobulbar tract, which controls movements of the face and neck.

Anatomy

The pyramidal tract begins in the cerebral cortex, where neurons known as upper motor neurons originate. These neurons send their axons down through the internal capsule, a white matter structure located deep within the brain. From there, the axons continue down through the midbrain and pons, before reaching the medulla oblongata.

In the medulla, the axons of the corticospinal tract decussate, or cross over, to the opposite side of the brain. This is why damage to one side of the brain often results in paralysis on the opposite side of the body. After decussation, the axons continue down the spinal cord, where they synapse with lower motor neurons in the anterior horn.

The axons of the corticobulbar tract, on the other hand, do not decussate in the medulla. Instead, they synapse with lower motor neurons in the brainstem, which control the muscles of the face and neck.

Function

The primary function of the pyramidal tract is to control voluntary movements. This is achieved through the action of the upper and lower motor neurons. The upper motor neurons initiate the movement by sending a signal down their axons to the lower motor neurons. The lower motor neurons then send a signal to the muscles, causing them to contract.

In addition to voluntary movements, the pyramidal tract is also involved in the control of reflexes. This is because the upper motor neurons can inhibit or facilitate the action of the lower motor neurons, depending on the situation.

Clinical significance

Damage to the pyramidal tract can result in a number of neurological disorders, including spastic paralysis, hemiplegia, and pseudobulbar palsy. These conditions are characterized by muscle weakness, increased muscle tone, and abnormal reflexes, among other symptoms.

Pyramidal tract Resources
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