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Development of the XIth or spinal accessory nerve in the chick. With some notes on the hypoglossal and upper cervical nerves
Author(s) -
Rogers K. T.
Publication year - 1965
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901250208
Subject(s) - anatomy , ganglion , biology , spinal cord , superior cervical ganglion , neuroscience
Bodian stained serial sections show that N. XI first appears at Stage 19. By Stage 21 there are at least 350 rootlet fibers, and about 65 fibers have reached N. X in their growth. N. XI merges with the second cervical ganglion posteriorly, and passes through the first cervical ganglion while the latter is present. Contrary to findings from gross dissection, histological sections show that the second cervical ganglion is retained in the adult, and N. XI retains its relation to this ganglion. Nerve cells present along N. XI in the embryo disappear by adulthood from a little anterior to ganglion C. 2 to the most anterior levels of C. 1, possibly migrating along the nerve rather than degenerating. Proprioceptice fibers for the nerve may originate from cells that lie in the adult in or near the ganglion of C. 2 or in or near the jugular ganglion. Motor fibers originate from cells of the ventral horn of C. 2, C. 1, and the lowest medullary levels, and leave the cord and medulla by a route similar to the fibers of von Lenhossék of more posterior levels. N. XI in the adult contains about 350 spinal and 215 medullary fibers. The two main roots of N. XII on each side send strong lateral branches to the cervical musculature before joining to form the nerve to the tongue, to which C. 1 and C. 2 ventral roots also contribute.