Hilum of suprarenal gland

The hilum of the suprarenal (adrenal) gland is the area on the surface of the gland typically located on its anterior or anteromedial aspect where the central suprarenal vein exits the gland. It represents the principal neurovascular gateway of the organ, analogous to the hilum of other organs such as the kidney or lung.

Unlike many organs with a well-defined hilum through which both arteries and veins pass, the adrenal gland is distinctive in that its arterial supply does not enter through a single hilum. Instead, numerous small arterioles from the superior, middle, and inferior suprarenal arteries (arising from the inferior phrenic artery, abdominal aorta, and renal artery, respectively) penetrate the gland capsule diffusely across its surface.

The hilum is therefore defined primarily by the exit point of the central (main) adrenal vein, which is the single dominant venous drainage vessel of each gland. On the right side, this short vein exits the anterior surface and drains directly into the posterolateral aspect of the inferior vena cava. On the left side, the vein exits from the mid-portion of the anterior/inferior surface and drains into the left renal vein, often joined by the left inferior phrenic vein.

Lymphatic vessels and autonomic nerve fibers also traverse the hilar region.