Lumbocostal arch

Lumbocostal arch (also known as the lumbar costal arch or arcuate ligament) is a structure in the human anatomy that is part of the posterior abdominal wall. It is a fibrous arch that connects the lower border of the diaphragm to the upper border of the quadratus lumborum muscle and the psoas major muscle.

Structure

The lumbocostal arch is a fibrous arch that is formed by the aponeurosis of the transversus abdominis muscle. It is attached to the lower border of the diaphragm and the upper border of the quadratus lumborum muscle and the psoas major muscle. The lumbocostal arch is divided into two parts: the medial lumbocostal arch and the lateral lumbocostal arch.

Medial Lumbocostal Arch

The medial lumbocostal arch is attached to the upper border of the psoas major muscle. It is also known as the medial arcuate ligament.

Lateral Lumbocostal Arch

The lateral lumbocostal arch is attached to the upper border of the quadratus lumborum muscle. It is also known as the lateral arcuate ligament.

Function

The lumbocostal arch serves as a point of attachment for the diaphragm, which is the primary muscle involved in respiration. It also provides a passageway for the aorta, the azygos vein, and the thoracic duct to pass from the thorax to the abdomen.

Clinical Significance

The lumbocostal arch is an important landmark in surgical procedures involving the posterior abdominal wall. Its location and structure can be affected by conditions such as diaphragmatic hernia and abdominal aortic aneurysm.

See Also

• Diaphragm (anatomy)
• Quadratus lumborum muscle
• Psoas major muscle
• Transversus abdominis muscle
• Aorta
• Azygos vein
• Thoracic duct