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Articles
- Research relating to ETS
Microscopic study of sections of the
intrathoracic ramus joining the first and second thoracic nerves taken
at autopsy in two cases in which this ramus was well developed revealed
that myelinated fibers occur there more frequently than they do in sections
of spinal nerves distal to the communicating rami. Fibers of small caliber
with thin myelin sheaths occur in abundance in these sections; thinly
myelinated fibers of small caliber also occur in abundance in sections
of the gray rami in these cases. These observations regarding the frequency
of unmyelinated fibers in the ramus joining the first and second thoracic
nerves in man were corroborated in sections of this ramus taken from
animals (cats and dogs). While a small caliber and a thin myelin sheath
or complete absence of myelin are not absolute criteria of the sympathetic
nature of nerve fibers, the majority of these fibers in the ramus doubt
less are sympathetic.
The foregoing observations show clearly that the intrathoracic ramus connecting
the first and second thoracic nerves, which is present in man in a large percentage
of cases, contains sympathetic fibers. Whenever this ramus joins the first
thoracic nerve proximal to the origin of the first intercostal nerve it constitutes
a pathway through which sympathetic fibers that leave the sympathetic trunk
below the stellate ganglion enter the brachial plexus.
Recent studies of the innervation of the arteries of the extremities in mammals
(Hirsch, 1925;2 Wiedopf, 1925,3 and Kerper, 1927)4 show clearly that sympathetic
fibers which are carried peripherally in the larger nerve trunks join the arteries
at intervals along their course. Sympathetic fibers reach the vessels of the
extremities mainly via these nerves. Few if any sympathetic fibers extend peripherally
along the walls of the vessels. The nerves that supply the voluntary muscles
include not only the sympathetic fibers which, as shown by Boeke (1913, 1927)5
and others, terminate on striated muscles, but also sympathetic fibers which
supply the blood vessels in the muscle (Kuntz 1927).6 As the first thoracic
nerve contributes largely to both the median and ulnar nerves, the sympathetic
fibers contained in it, including those which enter via the ramus from the
second thoracic nerve when ever this ramus is present, are relatively widely
distributed to blood vessels and other tissues in the upper extremity.
2. Hirsch,
L.: Ueber die Nervenversorgung der Gefasse im Hinblick auf die Probleme
der periateriellen Sympathektomie, Arch. f. klin. Chir. 137:281,
1925.
3. Wiedopf, O.: Der Verlauf der Gefassnerven in den Extremitaten und deren
Wirkung bei der periarteriellen Sympathektomie, Miinchen. med. Wchnschr. 72:413,
1925.
4. Kerper, A. H.: The Innervation of the Arteries of the Extremities, Thesis,
to be published.
5. Boeke, J.: Die doppelte (motorische und sympathische) efferente Imlerva
tion der quergestreiften Muskelfasem, Anat. Anz. 44:343, 1913. Die morpholo
gische Grundlage der sympatischen Innervation der quergestreiften Muskelfasern,
Ztschr. f. mikr-anat. Forsch. 8:561, 1913.
6. Kuntz, A.: On the Occurrence of Sympathetic Nerve Fibers in Muscles of the
Extremities Following Experimental Degeneration of the Spinal Nerves, J. Comp.
Neurol., 1927, vol. 43.
In view of the foregoing anatomic data, extirpation of the stellate ganglion or section of the gray rami connecting this ganglion with the brachial plexus is inadequate to insure complete sympathetic denervation of the blood vessels of the upper extremity in cases in which the inconstant intrathoracic ramus connecting the first and second thoracic nerves is present. In such cases, complete sympathetic denervation of the upper extremity requires extirpation of the stellate ganglion and of the upper portion of the thoracic sympathetic trunk to the level below the communicating rami of the second thoracic nerve, or section of the communicating rami of the second thoracic nerve and any peripheral rami arising from the thoracic sympathetic trunk above this level, in addition to section of the gray rami connecting the stellate and middle cervical ganglions with the brachial plexus.
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