ove one hind leg, to see bladder and genital ducts
better (compare Sheet 10). Wash away any blood that may flow. Turn
all the intestines over to the animal's right, and see the dorsal aorta
and vena cava inferior of the abdomen, the inferior mesenteric artery,
and the spermatic (or ovarian) artery (compare, of course, with figure
in book). In front, immediately dorsal to the spleen, is a variable
quantity of lymphoidal tissue, which must be very carefully cleared to
see the superior mesenteric and coeliac arteries. Separate Spigelian
lobe from stomach, and look for vagus nerve descending by
oesophagus, solar plexus around the superior mesenteric artery, and
thrown up very distinctly by the purple vena cava inferior beneath, and
the splanchnic nerve. To see the abdominal sympathetic behind,
gently remove the peritoneum that lies on either side of the aorta;
blood-vessels will be seen running in between the vertebral bodies,
and the sympathetic chain, with its ganglia, made out very distinctly,
as it runs across them longitudinally. Now cut oesophagus just in
front of stomach, and cut the rectum, cut through the mesentery
supporting the intestine, and remove and unravel alimentary canal; cut
open, wash out, and examine caecum and stomach. Bleeding to a
considerable extent is inevitable, chiefly from the portal vein. The liver
had better remain if the same rabbit is to serve for the second
dissection.
Second Dissection.-- Skin front of thorax and neck. Note subclavian
veins running out to fore limbs-- avoid cutting these. Cut through ribs
and remove front of thorax, to expose its contents; cut up middle line
of neck, and clear off small muscle bands, to expose bloodvessels;
pick away carefully whatever is left of thymus gland; make out
structure of heart and blood-vessels, as described, in Chapter 3; note
larynx and trachea. Now proceed to the examination of the nerves of
this region. See phrenic nerve, by vena cava inferior, and between
heart and lungs, and sympathetic, running over the heads of the ribs.
By the common carotids will be found the large white vagus nerve, the
greyish sympathetic, and a small branch of X., the depressor. Make
out branches of X. named in text. The big white cervical spinal nerves
will be evident dorsally. Clear forward into the angle between the jaw
and the bulla tympani, to see XII. and XI.; IX. will be found, lying
deeper, dorsal to the carotid artery and body of the hyoid. Compare
with f
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