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Components of the Vagus Nerve

1932; SAGE Publishing; Volume: 29; Issue: 9 Linguagem: Inglês

10.3181/00379727-29-6257

1535-3702

R. L. Jones,

Neonatal and fetal brain pathology

The number of unmyelinated fibers in the cervical vagus trunk greatly exceeds the number of myelinated fibers. Kiss regards the unmyelinated fibers as sympathetic fibers which join the vagus trunk mainly in the region of the superior cervical sympathetic ganglion. He denies the existence of unmyelinated fibers in the vagus rootlets. According to Ranson and Chase, and others, the unmyelinated fibers in the vagus trunk arise from cells in the brain stem and emerge in the vagus rootlets. In the present investigation, carried out on cats, anatomical and experimental studies were made of the relationships between the cervical sympathetic and vagus trunks and their myelinated and unmyelinated components. The superior cervical sympathetic and nodose ganglia were removed together from several cats. Threads were then tied to each of the ends of the respective trunks and the 2 ganglia were tied upon a glass frame with sufficient tension to draw them slightly apart, to provide an opportunity for the demonstration of any possible connections between them when the preparation was later sectioned. In several instances the cervical vago-sympathetic trunk was removed and sectioned transversely at intervals of less than 0.5 cm. Some of these preparations were stained with osmic acid and some with pyridine silver. Study of the sections showed that the 2 ganglia are connected by several small rami which contain both myelinated and unmyelinated fibers. These small rami contribute no more than a small fraction of the unmyelinated fibers of the vagus trunk. Sections of the vagosympathetic trunk taken at short intervals show no interconnecting branches between the vagus and sympathetic trunks distal to the nodose ganglion.