The Cambridge natural history, Vol. 04 (of 10)Warburton, Cecil
Science
The Cambridge natural history, Vol. 04 (of 10)
Warburton, Cecil
Animals
The intestinal nerves are shown arising from the haemal nerves and
entering the intestine. Those from the sixth and seventh neuromeres
pass through foramina in the endosternite, and communicate with a
plexus in the longitudinal abdominal muscles before entering the
intestine. The eighth passes just posterior to the endosternite and
joins the same plexus. Those from the first four branchial
neuromeres arise very near the abdominal ganglia, and are double in
their origins, the anterior branches joining the above-mentioned
plexus, and the posterior branches entering the intestine. The
fifteenth extends far back towards the rectum and anastomoses with
the sixteenth, which arises from the caudal branch of the sixteenth
haemal nerve, and innervates the rectum and anal muscles.
The segmental cardiac nerves (18) arise from the haemal nerves of the
sixth to the thirteenth neuromeres respectively. The most anterior
one passes to the inter-tergal muscles and the epidermis in the
median line, but the connections with the cardiac plexus have not
been made out. The next two (18) fuse to form a large nerve, which
passes to the inter-tergal muscles and epidermis, but has not been
observed to connect directly with the cardiac plexus. It, however,
sends posteriorly a branch, the pericardial nerve (20), which in
turn gives a branch to each of the cardiac nerves of the branchial
neuromeres, and then continues onward to the posterior margin of the
abdomen. This nerve lies in the epidermis. The median and lateral
cardiac nerves (22 and 21) are seen upon the walls of the heart. The
five cardiac nerves from the branchial neuromeres pass, in the
epidermis, to the median line, and dip down to the median nerve (22)
of the heart opposite the last five pairs of ostia (17). They
communicate with the pericardial nerve (20) and also with the
lateral sympathetic nerve (30).
Two post-cardiac nerves pass from the first and second post-branchial
nerves to the epidermis posterior to the heart.
The last cardiac nerve and the two post-cardiac nerves give off
branches which anastomose with each other and innervate the
extensors of the telson.
The lateral sympathetic nerve (30) receives branches from all the
neuromeres from the eighth to the fourteenth, either through the
cardiac nerves or the haemal nerves, and innervates the
branchio-thoracic muscles, extending with these far into the
cephalothorax.
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