Neuroanatomy, Pyramidal Tract Lesions

Excerpt

The central nervous system (CNS) is a complex network of components that allow an organism to interact with its environment. It is made up of multiple different parts, each of which plays a different role. Primarily, the CNS is formed by the upper motor neurons (UMN) which carry signals for movement down to the lower motor neurons (LMN) which signal the muscles to either contract or relax.

The UMN further subdivides into multiple tracts, each of which has specific functions within the body. Specifically, the pyramidal tract is the main pathway that carries signals for voluntary movement. Lesions to the pyramidal tract can lead to devastating consequences such as spasticity, hyperactive reflexes, weakness, and a Babinski sign (stroking the sole of the foot causes the big toe to move upward). These symptoms are all characteristic of an upper motor neuron lesion. However, certain symptoms are specific to a pyramidal tract lesion.