Blood

Anterolateral Abdominal Wall Arteries

The superior epigastric artery, one of the terminal branches of the internal thoracic artery, enters the upper part of the rectus sheath between the sternal and costal origins of the diaphragm (see Fig. 6.6). It descends behind the rectus abdominis muscle, supplying the upper central part of the anterior abdominal wall, and anastomoses with the inferior epigastric artery. The inferior epigastric artery is a branch of the external iliac artery just above the inguinal ligament. It runs upward and medially along the medial side of the deep inguinal ring (see Figs. 6.6, 6.11, and 6.15D). It pierces the transversalis fascia to enter the rectus sheath anterior to the arcuate line (see Fig. 6.17). It ascends behind the rectus muscle, supplying the lower central part of the anterior abdominal wall, and anastomoses with the superior epigastric artery.

The deep circumflex iliac artery is a branch of the external iliac artery just above the inguinal ligament (see Fig. 6.6). It runs upward and laterally toward the anterosuperior iliac spine and then continues along the iliac crest. It supplies the lower lateral part of the abdominal wall.

The lower two posterior intercostal arteries, branches of the descending thoracic aorta, and the four lumbar arteries, branches of the abdominal aorta, pass forward between the muscle layers and supply the lateral part of the abdominal wall (see Fig. 6.6).

Veins

The superficial veins form a network that radiates out from the umbilicus (see Fig. 6.7). Above, the network drains into the axillary vein via the lateral thoracic vein and, below, into the femoral vein via the superficial epigastric and great saphenous veins. A few small veins, the paraumbilical veins, connect the network through the umbilicus and along the ligamentum teres to the portal vein. This forms an important portal–systemic venous anastomosis.

The deep veins of the abdominal wall, the superior epigastric, inferior epigastric, and deep circumflex iliac veins, follow the arteries of the same name and drain into the internal thoracic and external iliac veins. The posterior intercostal veins drain into the azygos veins, and the lumbar veins drain into the inferior vena cava.

Caval Obstruction

If the superior or inferior vena cava is obstructed, the venous blood causes distention of the veins running from the anterior chest wall to the thigh. The lateral thoracic vein anastomoses with the superficial epigastric vein, a tributary of the great saphenous vein of the lower limb. In these circumstances, a tortuous varicose vein may extend from the axilla to the lower abdomen (see Fig. 6.7).

Portal Vein Obstruction

In cases of portal vein obstruction, the superficial veins around the umbilicus and the paraumbilical veins become grossly distended (see Fig. 6.7). The distended subcutaneous veins radiate out from the umbilicus, producing in severe cases the clinical picture referred to as caput medusae (Fig. 6.23C).

Anterolateral Abdominal Wall Lymphatics

The lymph drainage of the skin of the anterior abdominal wall above the level of the umbilicus is upward to the anterior axillary (pectoral) group of nodes, which can be palpated just beneath the lower border of the pectoralis major muscle (see Fig. 6.23A). Below the level of the umbilicus, the lymph drains downward and laterally to the superficial inguinal nodes. The lymph of the skin of the back above the level of the iliac crests is drained upward to the posterior axillary group of nodes, palpated on the posterior wall of the axilla (see Fig. 6.23B). Below the level of the iliac crests, lymph drains downward to the superficial inguinal nodes.