hilum

The hilum (hila) is an anatomical region of an organ where structures such as vessels, nerves, and ducts enter and exit. It is typically a recessed or indented area on the organ’s surface that serves as a conduit for these structures. The term is also used in botany to denote the seed’s attachment scar.

Kidneys: The renal hilum is the medial border of the kidney, where the renal artery enters, the renal vein exits, and the ureter begins. It lies within the renal sinus and provides access to the renal pelvis and the calyces.

Lungs: The hilum of the lung, or the lung root, is the mediastinal surface through which the main bronchus, pulmonary artery, pulmonary veins, nerves, and lymphatics enter and exit the organ.

Liver: In the liver, the porta hepatis (often called the hepatic hilum) is the region on the inferior surface containing the hepatic artery proper, the portal vein, and the common hepatic duct, together with nerves and lymphatics. It acts as the conduit for the portal triad entering and leaving the liver.

Spleen: The splenic hilum is on the visceral surface where the splenic artery and vein, along with nerves and lymphatics, enter and exit the spleen; it is bordered by the splenorenal and gastrosplenic ligaments.

Other organs: Structures analogous to a hilum occur in various organs, including the ovary and testis, where vessels and ducts pass into the organ at a defined entry point.

In botany: The hilum is the scar on a seed marking the point of attachment to the ovule, often visible on the seed coat.