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Welcome to 2 minute neuroscience, where I simplistically explain neuroscience topics
in 2 minutes or less.
In this installment I will discuss the spinal cord in cross-section.
When you look at the spinal cord in cross-section at any level you will see a butterfly-shaped
region of grey matter surrounded by white matter.
The grey matter is made up of the cell bodies of neurons while the white matter consists
of axons that travel up the spinal cord to the brain and down the spinal cord to the
body.
There is a small groove called the posterolateral sulcus where dorsal roots enter the cord carrying
sensory information.
There is another groove that is not very distinct on the front of the cord called the anterolateral
sulcus.
Ventral roots leave the cord from the anterolateral sulcus to carry motor information to the muscles.
The grey matter is divided into three regions.
The posterior horn contains interneurons that make connections within the spinal cord and
neurons that enter ascending pathways carrying sensory information to the brain.
There is a section of the posterior horn called the substantia gelatinosa that contains neurons
that specifically carry pain and temperature sensations to the brain.
The anterior horn contains the cell bodies of motor neurons that activate skeletal muscle.
These neurons, called alpha motor neurons, leave the cord in the ventral roots and represent
the way the nervous system enacts voluntary and involuntary movements.
The intermediate grey matter has some characteristics of the areas surrounding it, but it also contains
neurons involved in autonomic functions, or functions that are automatic and occur without
conscious control like heart rate and respiration
The white matter of the spinal cord consists of bundles of ascending and descending fibers
that carry sensory information to the brain and motor information to the body, respectively.
These bundles of fibers are called funiculi.
The back of the spinal cord contains the posterior funiculi, which contain important pathways
that carry information about touch and limb position to the brain.
The lateral funiculi are found in the lateral portion of the cord; important pain pathways
are found here as well as important descending pathways that are responsible for causing
movement.
The anterior funiculi contain various ascending and descending pathways.