Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 76, 1946-47
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II.—The Systemic Arch. (Plate 43.)

From before backward, the branches arising from the left systemic arch before its junction with the right arch to form the dorsal aorta are as follows:—

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(i)

An oesophageal artery.
(ii)

A gastric artery, passing to the stomach.
(iii)

The occipito-vertebral artery, passing to the dorsal region of the body.
(iv)

The subclavian artery, supplying the shoulder and arm.
(v)

Three dorso-lumbar arteries, supplying the muscles of the body wall.
(vi)

Three branches, passing to the oviduct, kidneys and fat-body of the same side.

The branches of the right systemic arch are symmetrical with those of the left, except for the lack of oesophageal and gastric arteries on the right side.

The dorsal aorta gives rise to a further series of branches:

(1)

The coeliaco-mesenteric artery, supplying the alimentary canal and its associated glands.
(2)

A variable number of urinogenital arteries, supplying the kidneys, gonads and oviducts.
(3)

Several pairs of small dorso-lumbar arteries, passing to the dorsal body wall.
(4)

An anterior haemorrhoidal artery, arising either before or behind the last pair of renal arteries and passing to the large intestine.
(5)

A posterior haemorrhoidal artery, supplying the large intestine and the bladder.
(6)

Two iliac arteries, formed by the ultimate bifurcation of the dorsal aorta and passing to the hind limbs.

The occipito-vertebral artery, which arises opposite the level of the shoulder, passes inward and upward towards the vertebral column. Close to the latter, a small central branch comes off the main trunk and passes inward to the ventral surface of the spinal cord, where it unites with the anterior spinal artery. The main artery continues upward to the dorsal level of the vertebral column, after which it passes forward and outward as the occipital artery until it reaches the inner posterior border of the orbit. Before descending to supply the lining of the inner wall of the orbit, the occipital artery gives off two branches, one of which supplies the skin covering the outer wall of the orbital region, while the other passes downward to the roof of the mouth.

In Leiopelma, a vessel corresponding fully to the vertebral artery of Rana does not exist, and the only representative of the “rami spinales” (Ecker, 1864) of the latter is the small ventral vessel which unites with the anterior spinal artery. The functions of the vertebral artery appear to be served in Leiopelma by the dorso-lumbar arteries arising from the systemic arch and renal arteries and supplying the vertebral column and muscles surrounding it. A vertebral artery is lacking also in Hyla aurea. (Marriner, 1905.)

The subclavian artery conforms largely in its distribution to the same vessel in Rana, but exhibits minor differences in the positions of the finer branches supplying skin and muscles. Leiopelma exhibits no trace of the costo-cervical branch of the subclavian artery, but its function is carried out by means of the three pairs of dorso-

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lumbar arteries arising from the systemic arches. The latter run between the transverse processes of the second to the fifth vertebrae and pass through the intervertebral foramina to supply the vertebral canal. In addition, they feed the surrounding muscles.

An interesting feature shown in Leiopelma is the presence of three oviducal and renal arteries arising from the backwardly-curving region of each systemic arch. (Plate 42.) The two anterior branches are short vessels which pass directly outward and backward to the anterior region of the corresponding oviduct. Shortly before the dorsal aorta is formed, a third artery takes its origin. This, after branching to supply the fat-body, passes diagonally back over the antero-ventral surface of the kidney, until it reaches the outer border of this organ. It then turns backward and runs toward the posterior end of the kidney, sending out, more or less at right angles, several arteries which ramify over the surface of the corresponding oviduct.

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