The superior epigastric artery is a terminal branch of the internal thoracic artery (formerly known as the internal mammary artery). It supplies the anterior abdominal wall and parts of the diaphragm.
Location
The superior epigastric artery arises from the internal thoracic artery at the level of the sixth or seventh intercostal space. After originating, it descends into the anterior abdominal wall, entering the rectus sheath by passing posterior to the costal margin. It travels within the rectus abdominis muscle, supplying the upper portion of the abdominal wall. The superior epigastric artery anastomoses with the inferior epigastric artery, a branch of the external iliac artery, in the lower abdominal region, forming a vital vascular network for the anterior abdominal wall.
Anatomy
Origin
The superior epigastric artery is one of the terminal branches of the internal thoracic artery (also known as the internal mammary artery), which arises from the subclavian artery. The internal thoracic artery descends along the inside of the anterior thoracic wall, and at the level of the sixth or seventh intercostal space, it bifurcates into the musculophrenic artery and the superior epigastric artery.
Course
After branching from the internal thoracic artery, the superior epigastric artery descends into the abdominal region. It enters the rectus sheath by passing posterior to the costal margin at the level of the seventh costal cartilage. The artery then travels inferiorly within the substance of the rectus abdominis muscle, which lies within the anterior abdominal wall. Along its course, the artery supplies the upper part of the rectus abdominis muscle as well as the overlying skin and fascia.
Relations
- Anteriorly: The superior epigastric artery is covered by the anterior layer of the rectus sheath, which also encloses the rectus abdominis muscle.
- Posteriorly: The artery runs anterior to the transversalis fascia and the peritoneum.
- Laterally: The superior epigastric artery is located near the lateral edges of the rectus sheath and is in proximity to the lower part of the ribcage.
Branches
As it descends through the rectus abdominis, the superior epigastric artery gives off multiple small branches:
- Muscular branches: These supply the rectus abdominis muscle, as well as other muscles in the anterior abdominal wall.
- Cutaneous branches: These small branches emerge from the rectus sheath to supply the overlying skin of the upper anterior abdominal wall.
Termination
The superior epigastric artery continues its course inferiorly within the rectus sheath until it reaches the level of the umbilicus. At this point, it forms an important anastomosis with the inferior epigastric artery, which ascends from the external iliac artery. This anastomosis ensures that blood supply to the anterior abdominal wall is maintained even if one of the arteries becomes compromised.
Anastomoses
The primary anastomosis of the superior epigastric artery is with the inferior epigastric artery, which ascends from the external iliac artery. This connection forms part of the collateral circulation of the anterior abdominal wall, allowing the two arteries to compensate for each other if one is obstructed. The superior epigastric artery also forms smaller anastomoses with branches from the lower intercostal arteries and the musculophrenic artery.
Variations
While the typical anatomy of the superior epigastric artery follows the course described, there can be some anatomical variations. The size of the artery may differ between individuals, and the extent of its contribution to the anterior abdominal wall can vary based on the prominence of its anastomoses with the inferior epigastric artery. In some cases, variations in the internal thoracic artery may affect the branching pattern of the superior epigastric artery.
Function
The superior epigastric artery plays a vital role in supplying blood to the upper anterior abdominal wall, ensuring the proper functioning of muscles and overlying skin. It forms a crucial part of the vascular network that maintains blood supply to the abdominal wall and supports other physiological functions.
Blood Supply to the Rectus Abdominis Muscle
The primary function of the superior epigastric artery is to supply oxygenated blood to the rectus abdominis muscle, a key muscle in the anterior abdominal wall. The rectus abdominis is responsible for flexion of the vertebral column, maintaining posture, and supporting movements such as bending forward and stabilizing the core during physical activity. As the artery descends through the rectus sheath, it nourishes the upper portion of this muscle, ensuring that it receives sufficient oxygen and nutrients for contraction and endurance.
The superior epigastric artery provides essential vascular support for the rectus abdominis muscle, particularly during activities requiring core strength, such as lifting, running, and other physically demanding movements.
Blood Supply to the Anterior Abdominal Wall
The superior epigastric artery also supplies the anterior abdominal wall, including the skin and fascia overlying the rectus abdominis muscle. It provides small cutaneous branches that emerge from the rectus sheath and vascularize the skin, ensuring the integrity of the abdominal wall’s surface layers. This is important for the health of the skin, its ability to heal after injury, and its role in protecting the underlying muscles and organs.
Additionally, the artery supports the abdominal wall’s structural components, such as the rectus sheath, which encloses the rectus abdominis muscle. The blood flow provided by the superior epigastric artery helps maintain the strength and elasticity of these tissues, contributing to abdominal wall stability.
Support for Collateral Circulation
Another significant function of the superior epigastric artery is its contribution to collateral circulation in the anterior abdominal wall. It forms a key anastomosis with the inferior epigastric artery, a branch of the external iliac artery, which supplies the lower part of the abdominal wall. This anastomotic network ensures that the entire anterior abdominal wall remains well-vascularized, even if one of the arteries becomes obstructed or compromised due to trauma, surgery, or vascular disease.
This redundancy in blood supply is crucial for maintaining the health of the abdominal wall muscles and tissues. The collateral circulation allows the superior epigastric artery to support the blood flow of the inferior epigastric artery and vice versa, ensuring continuous nourishment and oxygenation of the abdominal muscles and skin.
Support for Healing and Regeneration
By providing a steady supply of blood to the abdominal wall, the superior epigastric artery plays an essential role in tissue healing and regeneration. The abdominal wall is frequently subject to strain and injury, particularly during physical activities, surgeries, or trauma. Adequate blood flow from the superior epigastric artery helps deliver oxygen, nutrients, and immune cells to injured tissues, supporting faster healing and minimizing the risk of complications such as necrosis or poor wound healing.
In abdominal surgeries, including procedures such as hernia repair or laparotomy, the integrity of the superior epigastric artery is crucial for ensuring adequate blood supply to the incision area. Its contribution to tissue repair and recovery is essential for successful postoperative outcomes.
Vascularization of the Diaphragm
The superior epigastric artery also contributes to the vascularization of the diaphragm, particularly the anterior portions of the muscle. The diaphragm plays a critical role in breathing, separating the thoracic and abdominal cavities. By supplying blood to the upper regions of the diaphragm, the superior epigastric artery supports respiratory function, helping the diaphragm maintain its contractile activity during inhalation and exhalation.
Although the superior epigastric artery primarily supplies the abdominal wall, its contribution to the diaphragm’s vascular network is important for the muscle’s endurance and efficiency in the respiratory process.
