A hilum is a depression or fissure where crucial structures, such as blood vessels and nerves, enter or exit an organ. Think of it as a gateway or access point. This definition applies across various organs, not just the lungs.
Hilum in Different Organs
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Lungs: The hilum of the lung is where the bronchus, blood vessels (pulmonary arteries and veins), and nerves enter and exit the lung. It acts as an anchor, securing the lung in place and providing a vital pathway for the transport of oxygen, nutrients, and nerve signals. (What is the hilum?, Hilum of the Lung: Overview of Anatomy, Function, and Illnesses, Hilum | anatomy | Britannica) Enlargement of the hilum can be a sign of conditions like lung cancer or pulmonary hypertension. (Hilum of the Lung: Causes of Masses and Enlarged Lymph Nodes)
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Seeds: In botany, a hilum is the scar on a seed where it was attached to the ovule within the plant. (Hilum Definition & Meaning - Merriam-Webster)
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Kidney: Similar to the lung, the kidney's hilum serves as the entry point for blood vessels, nerves, and the ureter.
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Liver: The liver also possesses a hilum, functioning as the entry and exit point for its vascular supply and bile ducts. (Hilum (anatomy) - Wikipedia)
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Other Organs: The hilum concept extends to other organs, consistently representing the point of entry and exit for crucial structures.
Medical Significance
The hilum's location and condition often hold clinical significance. For instance, hilar tumors, located near the hilum of an organ, can have different prognoses compared to non-hilar tumors. (Hilar location is an independent prognostic factor for recurrence in ..., Unilateral Pulmonary Hilar Tumor Mass: Is It Always Lung Cancer ...) In the context of cancer, the term "hilar" is frequently used to describe the location of a tumor, like in hilar cholangiocarcinoma (bile duct cancer near the hilum of the liver). (Hilar cholangiocarcinoma - Overview - Mayo Clinic, Cholangiocarcinoma (Bile Duct Cancer))