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The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem. There are three groupings of neurons that are involved in the pathway: first-order neurons, second-order neurons, and third-order neurons.
The dorsal column nuclei each have an associated nerve tract in the spinal cord, the gracile fasciculus and the cuneate fasciculus, together forming the dorsal columns. Both dorsal column nuclei contain synapses from afferent nerve fibers that have travelled in the spinal cord. [2] They then send on second-order neurons of the dorsal column ...
A small nerve may consist of a single funiculus, but a larger nerve will have several funiculi collected together into larger bundles known as fascicles. Fascicles are bound together in a common membrane, the epineurium. [1] [2] Funiculi in the spinal cord are columns of white matter. [3] [4] Examples include: Anterior funiculus of the spinal cord
Above the level of the eight thoracic nerve its size diminishes, and the column ends opposite the last cervical or first thoracic nerve. It is represented, however, in the other regions by scattered cells, which become aggregated to form a cervical nucleus opposite the third cervical nerve, and a sacral nucleus in the middle and lower part of ...
The two main tracts are the dorsal spinocerebellar tract, and the ventral spinocerebellar tract. Both of these tracts are located in the peripheral region of the lateral funiculi (white matter columns). [1] Other tracts are the rostral spinocerebellar tract, and the cuneocerebellar tract (posterior external arcuate fibers). [2]
Subacute combined degeneration of spinal cord, also known as myelosis funiculus, or funicular myelosis, [1] also Lichtheim's disease, [2] [3] and Putnam-Dana syndrome, [4] refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin B 12 deficiency (most common).
Collectively, the ascending sensory fibers are called the dorsal column because ascending fibers gather at the dorsal funiculus in the spinal cord. [5] The dorsal funiculus is located between the dorsal horn and the medial line in the spinal cord. There are three types of neurons in the pathway: first-, second-, and third-order neurons.
The dorsal column nuclei are responsible for fine touch, vibration, proprioception and two-point discrimination. The fibers of this decussation are called the internal arcuate fibers and are found at the superior aspect of the closed medulla oblongata, superior to the motor decussation. Neurons of these nuclei are second-order neurons in the ...