Part 4

(c) The hypoglossal and the glossopharyngeal nerves, both running alongside of the lingual artery.

Make an enlarged drawing showing the above parts (a) and (b).

2. Note the inferior vena cava, receiving the renal veins from the kidneys, the hepatic veins from the liver, and opening into the sinus venosus.

3. Trace back the abdominal vein, and note that it is formed by the union of the two pelvic veins, which pass along the bases of the legs. The pelvic veins occur deep down in the body under the posterior part of the pelvic girdle, which should be cut through in order to see them. At the union of the pelvic veins to form the abdominal vein a small rectal vein, passing along the ventral surface of the rectum, joins the abdominal vein.

In order to make out the femoral and the sciatic veins, turn the Platana over and remove the skin from the back of the leg. The femoral vein may then be seen lying on the surface of the leg, between two of the muscles. By carefully separating these muscles the whole of the femoral vein may be exposed. Deeper down in the muscles of the leg lies the sciatic vein, and, between the sciatic and the femoral veins, the internal iliac artery may be seen running alongside of the sciatic nerve.

Trace the femoral and the sciatic veins forward, and note that they join together at the point where they meet the pelvic veins and then run forward to the kidney as the renal portal vein on each side.

Turn the Platana over again on to its back and note the renal portal vein from the ventral side. Joining the renal portal vein is a large vein formed of two branches. The one branch arises in the abdominal wall, while the other passes along the base of the leg and joins the abdominal vein. On each side three dorso-lumbar veins join the renal portal vein.

Make a drawing showing the above parts.

B. Arterial System.

Distend the œsophagus with a piece of cotton wool or paper to show the blood vessels more clearly. Trace out the anterior part of the arterial system, made up of two branches of the truncus arteriosus each of which divides into:--

(a) The carotid arch passing to the head region.

(b) The systemic arch curving round the œsophagus.

(c) The pulmo-cutaneous arch to the lungs and the skin.

Fourth day.

=Arterial System= (continued).

1. Trace the carotid arch, which gives off:

(a) Two lingual arteries having a common point of origin near the carotid gland.

(b) A carotid artery passing to the head. At its origin it is slightly swollen into the carotid gland.

2. Trace the systemic arches which run backwards on each side of the body, meeting posteriorly to form the dorsal aorta. Each systemic arch gives rise to an artery which branches into:--

(i) A scapular artery to the pectoral girdle.

(ii) A cutaneous artery to the skin.

(iii) A brachial artery to the arm.

Trace the dorsal aorta backwards, and note that it gives rise to the cœliaco-mesenteric artery about midway between its origin and the origin of the first pair of renal arteries. The dorsal aorta then passes between the kidneys giving four renal arteries to each, and proceeds backwards and divides into an internal iliac artery to each leg. This artery lies between the femoral and the sciatic veins. From each of these arteries a branch is given off which divides into:

(i) An iliac artery to the muscles around the ilium.

(ii) A cutaneous artery to the skin of the body, just anterior to the leg.

(iii) A small artery to the anterior dorsal surface of the hind limb.

3. Trace the pulmo-cutaneous arch, which gives off:--

(a) A pulmonary artery, running along the outer side of the whole length of the lung.