Some modern extensions of Beaumont's studies on Alexis St. Martin : Beaumont Foundation Lectures / W.B. Cannon.

  • Cannon, Walter B. (Walter Bradford), 1871-1945.
Date:
[1933?]
Catalogue details

Licence: In copyright

Credit: Some modern extensions of Beaumont's studies on Alexis St. Martin : Beaumont Foundation Lectures / W.B. Cannon. Source: Wellcome Collection.

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    from the superior cervical ganglion high in the neck to fused ganglia in the pelvis. These ganglia are the seat of the cell bodies of the outlying neurones of this division. The fibers passing out from the ganglia to smooth muscle and glands are called “post¬ ganglionic fibers.” They are widely dis¬ tributed all over the body, to arterioles, to sweat glands, to hair muscles, to the genito¬ urinary tract, and to all parts of the alimen¬ tary canal and its glandular accessories. The fibers of the white rami, connecting the central nervous axis with the sympa¬ thetic ganglia, are designated “preganglion¬ ic fibers.” A peculiar feature of the ar¬ rangement of these fibers is that they not only reach to the nearest ganglion from their source, but pass through that one to neighboring ganglia up and down the chain, giving off collateral branches in each one. This arrangement of the preganglionic fibers results in an interlacing of their dis¬ tribution. In any ganglia there may be ax- ones from four or five different segments of the spinal cord; or, to put it differently, axones from any segment of the cord may pass through four or five different ganglia of the sympathetic chain, connecting the ganglia with one another and at the same time distributing to outlying neurones in each one. This mode of organization has two effects; it greatly increases the range of distribution of impulses coming out along any single fiber, and it also provides for dif¬ fuse distribution of impulses throughout the organism. Associated with the sympathetic system is