Inferior phrenic artery

Origin and course

The left and right inferior phrenic arteries usually arise as the first branches from the abdominal aorta. They take a superior course, passing anterolaterally to the corresponding crus of the diaphragm. At this level, both arteries give off 1-3 collateral superior suprarenal branches.

The right inferior phrenic artery curves around the posterior aspect of the inferior vena cava and continues along the right margin of the vena caval foramen. The left inferior phrenic artery passes behind the esophagus and then along the left margin of the esophageal hiatus. Both arteries reach the posterior margin of the central tendon of the diaphragm, where they split into their respective ascending (medial) and descending (lateral) branches.

Branches and supply

Each inferior phrenic artery divides into a descending (lateral) and ascending (medial) branch on the undersurface of the diaphragm. Before their terminal bifurcation, the inferior phrenic arteries give off a set of collateral branches to supply the ipsilateral suprarenal gland. These arteries are called the superior suprarenal arteries.

The descending (lateral) branches of both inferior phrenic arteries take a lateral course towards the respective sides of the thoracic cage. They supply the muscular portion of the diaphragm and terminate by anastomosing with the lower posterior intercostal and musculophrenic arteries. Via these anastomoses, the descending branches take part in the supply of the trunk wall.

The ascending (medial) branches of the left and right vessel differ in their course;

• The left ascending branch curves medially around the posterior side of the esophagus after which it splits into two branches. One of these branches anastomoses with its counterpart branch of the right inferior phrenic artery with which it supplies the distal esophagus and tendinous diaphragm. While the other branch anastomoses with the musculophrenic and pericardiacophrenic arteries, joining the supply system of the trunk wall and pericardium.
• The right ascending branch bifurcates after curving around the inferior vena cava. One of its branches anastomoses with its left-sided counterpart, while the other one diminishes along its course over the lateral part of the abdominal surface of the diaphragm.

The superior suprarenal arteries arise from the inferior aspect of the trunk of each inferior phrenic artery at the level of diaphragmatic crura. They take a short inferior course to reach the ipsilateral adrenal gland and supply its superior portion.

Small collateral branches for the upper pole of the spleen and the capsule of the liver may arise from the inferior phrenic arteries.

Anatomical variations

There are certain noteworthy variations of the origins of the inferior phrenic arteries. The left inferior phrenic artery most commonly arises from the aorta. However, in a smaller number of cases it can be seen arising from the celiac trunk. The right artery has a higher degree of variation; it typically arises from either the aorta or the celiac trunk, but can also stem from the renal artery.