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Inferior phrenic artery

Medically Reviewed by Anatomy Team

  • Last updated on January 24, 2025

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The inferior phrenic artery is a paired vessel that primarily supplies blood to the diaphragm. It is one of the first branches of the abdominal aorta or may arise from other nearby arteries.

Location

The inferior phrenic artery originates near the abdominal aorta, just as it passes through the diaphragm at the level of the twelfth thoracic vertebra (T12).[7] It may arise directly from the aorta, the celiac trunk, or the renal arteries, depending on individual anatomical variation. The artery ascends to supply the undersurface of the diaphragm and often gives off small branches to nearby structures, such as the adrenal glands and esophagus. The right and left inferior phrenic arteries are located on either side of the diaphragm, with each artery curving upward along the muscle’s surface to ensure its blood supply.

Anatomy

Origin

The inferior phrenic artery is typically a paired artery, meaning there is a right and a left artery, each supplying blood to one side of the diaphragm. Its origin can vary among individuals:

  • Directly from the Abdominal Aorta: In most cases, the inferior phrenic artery arises directly from the abdominal aorta, just as it enters the abdominal cavity after passing through the diaphragm at the level of the T12 vertebra.[5]
  • From the Celiac Trunk: In some individuals, the artery originates from the celiac trunk, one of the major branches of the abdominal aorta.
  • From the Renal Arteries: Occasionally, the inferior phrenic artery may arise from the renal arteries, which supply blood to the kidneys.
  • From a Common Trunk: In certain cases, the right and left inferior phrenic arteries may arise from a common trunk that branches off from the abdominal aorta or celiac trunk.

Course

  • Right Inferior Phrenic Artery: The right inferior phrenic artery travels upward and to the right. It passes posterior to the inferior vena cava and ascends to the underside of the diaphragm, where it branches to supply the diaphragm’s muscular and tendinous portions. The artery may also provide small branches to the right adrenal gland and esophagus.
  • Left Inferior Phrenic Artery: The left inferior phrenic artery follows a similar upward course but to the left. It passes posterior to the esophagus and ascends along the left side of the diaphragm. The left inferior phrenic artery also gives off small branches to the left adrenal gland and esophagus.

Both arteries are closely related to the inferior surface of the diaphragm, where they fan out into smaller branches to supply the muscular and tendinous parts of the diaphragm.

Branches

The inferior phrenic artery gives off several branches as it ascends:

  • Diaphragmatic Branches: The primary branches of the inferior phrenic arteries are the diaphragmatic branches, which supply the muscular and tendinous parts of the diaphragm. These branches spread out over the inferior surface of the diaphragm and penetrate the muscle to ensure an adequate blood supply.
  • Adrenal Branches: Each inferior phrenic artery often gives off small superior adrenal arteries (or suprarenal arteries) that supply the adrenal glands. These arteries are typically small but important in providing additional blood flow to the adrenal glands, which are also supplied by other arteries (middle and inferior adrenal arteries).
  • Esophageal Branches: Small branches from the inferior phrenic arteries may supply the lower esophagus, particularly in the left inferior phrenic artery, which lies close to the esophageal hiatus in the diaphragm.

Relations

Right Inferior Phrenic Artery:

  • Anteriorly: The right inferior phrenic artery is related to the liver and the inferior vena cava, which it passes behind as it ascends to the diaphragm.[3]
  • Posteriorly: It is related to the right adrenal gland and kidney as it travels upward from the aorta.

Left Inferior Phrenic Artery:

  • Anteriorly: The left inferior phrenic artery is related to the stomach and the lower part of the esophagus, through which it often sends small branches.
  • Posteriorly: It passes behind the esophagus and is related to the left adrenal gland and kidney.

Length and Diameter

The length of the inferior phrenic artery varies depending on its origin. Its course from the aorta (or another origin) to the diaphragm is relatively short, as it needs to ascend only a few centimeters before it reaches its target. The artery’s diameter is typically small, as it supplies a limited region compared to larger arteries like the renal or celiac arteries.

Termination

The inferior phrenic artery terminates by dividing into several small branches that spread out over the inferior surface of the diaphragm. These branches penetrate the diaphragm to supply its muscular and tendinous parts, ensuring that the entire structure receives adequate blood flow.[1] The terminal branches provide collateral circulation to the diaphragm and nearby structures, such as the esophagus and adrenal glands.

Variations

Anatomical variations in the origin and course of the inferior phrenic artery are common. Some of these include:

  • Different Origin Points: As mentioned earlier, the artery may arise from the abdominal aorta, celiac trunk, or renal arteries. In some cases, it may even arise from a common trunk shared with other arteries.
  • Common Trunk: The right and left inferior phrenic arteries may arise from a common trunk before bifurcating into their respective sides.
  • Additional Branches: The inferior phren

Function

The inferior phrenic artery plays a crucial role in supplying blood to the diaphragm, the primary muscle responsible for breathing. In addition to its role in supporting diaphragmatic function, the artery also supplies blood to nearby structures, including the adrenal glands and esophagus. Below is a detailed breakdown of the functions of the inferior phrenic artery.

Blood Supply to the Diaphragm

The most critical function of the inferior phrenic artery is to provide oxygenated blood to the diaphragm, ensuring it functions effectively as the primary muscle in respiration. The artery’s branches fan out across the diaphragm, supplying both its muscular and tendinous portions. Specific roles include:

  • Nourishing Diaphragmatic Muscle: The diaphragm is a dome-shaped muscle that contracts and flattens during inhalation, creating negative pressure that draws air into the lungs. The oxygenated blood supplied by the inferior phrenic artery is essential for maintaining the energy needed for muscle contraction during breathing.
  • Maintaining Diaphragmatic Tone: The diaphragm is involved in a wide range of activities beyond normal breathing, such as aiding in coughing, sneezing, laughing, and even stabilizing the core during lifting.[8] The artery ensures that the muscle remains well-nourished and oxygenated during these activities, ensuring endurance and preventing fatigue.
  • Supplying the Central Tendon: The central tendon of the diaphragm, a thin but strong aponeurosis, also receives blood from the inferior phrenic artery. This is crucial for maintaining the structure and elasticity of the diaphragm, as the central tendon serves as the point of insertion for the muscle fibers.

Blood Supply to the Adrenal Glands

The inferior phrenic artery contributes to the blood supply of the adrenal glands via small branches known as the superior adrenal arteries. These arteries play an important role in supporting the adrenal glands’ hormone-producing functions:

  • Support for Hormone Production: The adrenal glands produce vital hormones, including cortisol, adrenaline, and aldosterone. These hormones regulate metabolism, blood pressure, and the body’s stress response. The blood supplied by the superior adrenal arteries, which branch off from the inferior phrenic arteries, ensures that the adrenal glands have sufficient oxygen and nutrients to sustain their hormone-producing activities.
  • Providing Blood to the Adrenal Cortex and Medulla: The adrenal glands consist of two distinct layers—the outer cortex and inner medulla. The superior adrenal arteries supply both regions, ensuring that each has the necessary resources to produce hormones. The cortex produces corticosteroids, while the medulla releases adrenaline and noradrenaline.

Blood Supply to the Lower Esophagus

The left inferior phrenic artery often provides small esophageal branches that supply blood to the lower portion of the esophagus, particularly where the esophagus passes through the diaphragm at the esophageal hiatus.[6] This blood supply supports several important functions:

  • Protection of Esophageal Mucosa: The lower esophagus is prone to damage from gastric acid reflux, especially in conditions like gastroesophageal reflux disease (GERD). The blood supplied by the esophageal branches of the inferior phrenic artery helps nourish the mucosal lining of the esophagus, aiding in repair and protecting the esophageal wall from acid damage.
  • Maintenance of the Esophagogastric Junction: The blood flow provided by the esophageal branches supports the integrity of the esophagogastric junction, where the esophagus meets the stomach. This region is critical in preventing the backflow of stomach contents into the esophagus, and the artery’s contribution ensures that this junction remains healthy and functional.

Oxygen and Nutrient Delivery

As with all arteries, the primary function of the inferior phrenic artery is to deliver oxygen and nutrients to the tissues it supplies. This process is essential for:

  • Cellular Metabolism: The diaphragm, adrenal glands, and lower esophagus are highly active tissues that require a constant supply of oxygen to support cellular respiration and generate energy. The blood provided by the inferior phrenic artery ensures that these cells receive the oxygen and nutrients they need to maintain normal metabolic processes.
  • Tissue Repair and Regeneration: The diaphragm, like all muscles, undergoes wear and tear as it contracts and relaxes during breathing. The blood supplied by the inferior phrenic artery supports the repair and regeneration of muscle tissue, ensuring that the diaphragm remains healthy and functional. The same applies to the esophagus, particularly in areas that experience irritation from acid reflux or other stressors.

Contribution to Collateral Circulation

The inferior phrenic artery plays a role in collateral circulation by providing alternate pathways for blood flow to nearby structures, especially in cases where other arteries are compromised. This is particularly important in situations where blood flow to the diaphragm, esophagus, or adrenal glands may be reduced due to blockages or injury.[4]

  • Collateral Blood Flow to the Diaphragm: The inferior phrenic arteries form anastomoses with other vessels that supply the diaphragm, such as the superior phrenic arteries (from the thoracic aorta) and the pericardiacophrenic arteries. These connections provide redundancy in blood supply, ensuring that the diaphragm remains oxygenated even if one artery is blocked or damaged.
  • Contribution to the Adrenal Glands: In addition to the superior adrenal arteries (from the inferior phrenic artery), the adrenal glands also receive blood from the middle adrenal arteries (from the aorta) and the inferior adrenal arteries (from the renal arteries). The inferior phrenic artery’s contribution helps create a network of vessels that ensures a continuous supply of blood to the adrenal glands, even if one of the other arteries is compromised.

Clinical Significance

The inferior phrenic artery is clinically significant because it supplies blood to the diaphragm, adrenal glands, and lower esophagus.[2] Its importance is highlighted in conditions involving the diaphragm, such as diaphragmatic paralysis or injury, where the artery’s blood supply is crucial for muscle function and recovery. The artery also plays a role in certain cases of adrenal tumors, such as pheochromocytomas, where the superior adrenal branches of the inferior phrenic artery may need to be carefully managed during surgery.

Additionally, the artery can be involved in esophageal and gastric surgeries due to its esophageal branches, which supply the lower esophagus. In cases of vascular diseases, such as aneurysms near the celiac trunk or abdominal aorta, the inferior phrenic artery’s role in collateral circulation becomes important to maintain blood flow to the diaphragm and surrounding structures. Understanding its course and variations is essential in abdominal and thoracic surgeries to prevent complications.

References

  1. Chaudhary V, Singh H, Abrahams PH. Clinical Anatomy of the Human Body. 2nd ed. New Delhi: Elsevier; 2015. ISBN 978-8131242355.
  2. Woodburne RT, Burkel WE. Essentials of Human Anatomy. 9th ed. New York: Oxford University Press; 1994. ISBN 978-0195063116.
  3. Krudy AG. Anatomy for Diagnostic Imaging. 3rd ed. London: Saunders; 2017. ISBN 978-0702067792.
  4. Testut L, Jacob O. Traité d’Anatomie Humaine. 8th ed. Paris: Masson; 1937.
  5. Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System. 3rd ed. New York: Thieme Medical Publishers; 2021. ISBN 978-1684204436.
  6. Detton AJ. Grant’s Dissector. 17th ed. Philadelphia: Lippincott Williams & Wilkins; 2020. ISBN 978-1975134607.
  7. Hollinshead WH. Textbook of Anatomy. 5th ed. New York: Harper & Row; 1968. ISBN 978-0721651235.
  8. Rosse C, Gaddum-Rosse P. Hollinshead’s Textbook of Anatomy. 5th ed. Philadelphia: Lippincott-Raven; 1997. ISBN 978-0397510720.