Fasciculus cuneatus

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Fasciculus cuneatus
File:Medulla spinalis - tracts - English.svg
Fasciculus cuneatus is 3b, in blue at upper right.
Gray672.png
Diagram of the principal fasciculi of the spinal cord.
Latin fasciculus cuneatus medullae spinalis
Gray's subject #185 763
Dorlands/Elsevier f_03/12355858

The fasciculus cuneatus (tract of Burdach, named for Karl Friedrich Burdach) is a bundle of nerves in the spinal cord which primarily transmits information from the arms. It is part of the posterior column-medial lemniscus pathway.

Physical characteristics

The fasciculus cuneatus is triangular on transverse section, and lies between the fasciculus gracilis and the posterior column, its base corresponding with the surface of the medulla spinalis.

Its fibers, larger than those of the fasciculus gracilis, are mostly derived from the same source, viz., the posterior nerve roots.

Some ascend for only a short distance in the tract, and, entering the gray matter, come into close relationship with the cells of the dorsal nucleus; while others can be traced as far as the medulla oblongata, where they end in the gracile nucleus and cuneate nucleus.

Information transmitted

The Fasciculus cuneatus transmits fine touch, fine pressure, vibration and proprioception information from spinal nerves located in dermatomes C1 through T6.

Neurons

The Fasciculus cuneatus tract is composed of 1st order neurons that synapse onto 2nd order neurons in the brain stem.

The 2nd order neurons decussate in the brainstem and continue on to the thalamus where the 2nd order neurons synapse onto 3rd order neurons.

The 3rd order neurons carry the received signals to the somatosensory cortex where the signals, in the form of action potentials are interpreted.

Additional images

Decussation of pyramids.
Superficial dissection of brain-stem. Lateral view.
The sensory tract.
Superior terminations of the posterior fasciculi of the medulla spinalis.
Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.




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