Corticospinal tract
Corticospinal tract | |
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Details | |
Identifiers | |
Latin | tractus corticospinalis |
FMA | 265580 |
Anatomical terms of neuroanatomy |
The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk.[1] There are more than one million neurons in the corticospinal tract, and they become myelinated usually in the first two years of life.
The corticospinal tract is one of the pyramidal tracts, the other being the corticobulbar tract.
Anatomy
The corticospinal tract originates in several parts of the brain, including not just the motor areas, but also the primary
There are two divisions of the corticospinal tract, the lateral corticospinal tract and the anterior corticospinal tract. The lateral corticospinal tract neurons cross the midline at the level of the medulla oblongata, and controls the limbs and digits.[1][3] The lateral tract forms about 90% of connections in the corticospinal tract;[2] the vast majority cross over in the medulla, while the rest (about 2-3%) remain ipsilateral. The anterior corticospinal tract neurons, the remaining 10%, stay ipsilateral in the spinal cord but decussate at the level of the spinal nerve in which they exit, and control the trunk, shoulder and neck muscles.[1]
Function
The primary purpose of the corticospinal tract is for voluntary motor control of the body and limbs.
However, connections to the somatosensory cortex suggest that the pyramidal tracts are also responsible for modulating sensory information from the body.[1]
Because most (75-80%) of the connections cross the midline at the level of the medulla and others at the level of the spinal cord, each side of the brain is responsible for controlling muscles on the opposite side of the body.[1]
After patients are lesioned in some part of the pyramidal tracts, they are paralyzed on the corresponding side of the body. However, they can re-learn some crude, basic motions, just no fine movements.[2]
This implies that the connections to these tracts are crucial for fine movement, and only partial recovery is possible if they are damaged.
References
- ^ a b c d e f g h Kolb, B. & Whishaw, I. Q. (2009). Fundamentals of human neuropsychology: Sixth edition. New York, NY: Worth Publishers.
- ^ a b c d e Purves, D. et al. (2012). Neuroscience: Fifth edition. Sunderland, MA: Sinauer Associates, Inc.
- ^ a b Kolb, B. & Whishaw, I. Q. (2014). An introduction to brain and behavior: Fourth edition. New York, NY: Worth Publishers.
- ^ ISBN 978-0-7216-0240-0.