The Paired Parietal Branches

The Inferior Phrenic arteries are the first branches which curve off the aorta as it enters the abdomen. They supply the under surface of the diaphragm.

The Lumbar arteries, of which there are usually four pairs, arise in series with the intercostal arteries. They pass backwards over the bodies of the lumbar vertebrae and between the adjacent transverse processes. They pass behind psoas and cross quadratus lumborum to get between the muscles of the anterior abdominal wall.

The Common Iliac arteries are formed by the bifurcation of the aorta at the lower border of the fourth lumbar vertebra.

They terminate opposite the lumbo-sacral joint by dividing into external and internal iliac. The common iliac arteries lie on the bodies of the fourth and fifth lumbar vertebrae and on psoas, and are separated anteriorly and externally from the coils of the small intestine by the peritoneum. Branches. - Internal iliac. External iliac.

The Internal Iliac artery arises opposite the lumbo-sacral articulation and passes down into the true pelvis, terminating opposite the upper border of the great sciatic notch by dividing into anterior and posterior divisions, giving off numerous branches which supply the pelvic wall and viscera, buttock, thigh, and external genital organs.

Posterior division Parietal: Ilio-lumbar - supply the muscles of the iliac Lateral-sacral - fossa and front of sacrum. Gluteal, passes out above pyriformis to supply the gluteal muscles.

Anterior division Visceral: supply the bladder and internal genital organs. Parietal: Obturator, supplies the obturator muscles.

Sciatic, passes out below pyriformis and supplies the muscles on the upper part of the thigh. Internal pudic - passes out below pyriformis, and, crossing the ischial spine with the pudic nerve, it enters and supplies the perineum.

The External Iliac artery arises opposite the sacro-iliac joint, and, passing outwards and forwards along the brim of the pelvis, it passes under the mid-point of Poupart's ligament and becomes the femoral artery. It lies on psoas and iliacus, and is separated from the colon and small intestine by the peritoneum.

Branches

Deep epigastric and deep circumflex iliac supply the muscles and skin of the anterior abdominal wall.

The Unpaired Parietal Branch

The Middle Sacral artery is a small artery arising from the back of the aorta just before its bifurcation. It passes down the middle of the sacrum, supplying the muscles and joints in the vicinity.

The Paired Visceral Branches

The Suprarenal arteries consist of three pairs of arteries for the supply of the suprarenal capsule. The middle pair arises from the aorta direct, the others are branches of adjacent arteries.

The Renal arteries arise opposite the second lumbar vertebra just below the superior mesenteric. Each passes transversely outwards over the crus of the diaphragm and the upper part of psoas to the hilum of the kidney. The right artery is a little longer than the left and often lower in position. It passes behind the inferior vena cava, the head of the pancreas, and the middle of the duodenum. The left artery lies behind the pancreas.