00:00 / 00:00
Ascending and descending spinal tracts are pathways that carry information up and down the spinal cord between brain and body.
The ascending tracts carry sensory information from the body, like pain, for example, up the spinal cord to the brain.
Descending tracts carry motor information, like instructions to move the arm, from the brain down the spinal cord to the body.
Both types of tracts are made up of neuronal axons that gather into long columns called funiculi, meaning long ropes, which are found inside the ventral, lateral and dorsal parts of the spinal cord.
Ascending tracts are sensory pathways that begin at the spinal cord and stretch all the way up to the cerebral cortex.
There are three types of ascending tracts, dorsal column-medial lemniscus system, spinothalamic (or anterolateral) system, and spinocerebellar system. They are made up of four successively connected neurons.
First order neurons are found inside dorsal root ganglions from where they gather sensory input and send it to the second order neurons, usually found inside the spinal cord or brainstem.
They further transmit it to the third order neurons found inside the thalamus, and then the fourth order neurons in the cerebral cortex.
While ascending through the spinal cord these tracts cross over to the opposite side of the central nervous system, or CNS, meaning that the left side of the brain receives sensory input from the right side of the body and vice versa.
These crossings are called decussations and they happen at different levels of the CNS for each of these tracts.
Let’s start with the dorsal column-medial lemniscus system which is a sensory pathway that transmits delicate sensations like vibration, proprioception or sensation of the position of bodyparts, two-point discrimination, and touch.
Throughout the body there are receptors like mechanoreceptors found in the skin that sense touch, or proprioceptors, like the muscle spindles and Golgi tendon organs in the muscles and joints that sense body position.
Ascending and descending spinal tracts are neural pathways within the spinal cord, which carry information up and down the spinal cord connecting the brain to the rest of the body.
The ascending tracts include the dorsal column-medial lemniscus system, the spinothalamic system, and the spinocerebellar system. These tracts carry sensory information from the periphery, such as pain, touch, and temperature to the brain.
The descending tracts include lateral and anterior corticospinal tracts, the vestibulospinal, the rubrospinal, and the reticulospinal tracts. These tracts carry motor information, such as a motor command to move the arm, from the brain down the spinal cord to the appropriate part of the body.
Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.