Structure/Morphology
The lateral arcuate ligament (lumbocostal arch) is the arch-like, thickened area of the fascia covering the quadratus lumborum muscle. It attaches to the anterior half of the twelfth rib, extends medially across the anterior aspect of the quadratus lumborum muscle, and attaches to the transverse process of the first lumbar vertebra.
Anatomical Relations
There are five arcuate ligaments associated with the diaphragm:
- one median arcuate ligament;
- two medial arcuate ligaments;
- two lateral arcuate ligaments.
The lateral arcuate ligament is located:
- anterior to the twelfth rib and quadratus lumborum muscle;
- inferior to the diaphragm.
The anterior ramus of the twelfth thoracic nerve (subcostal nerve) and the subcostal vessels pass through the gap formed by the lateral arcuate ligament.
Function
Both the right and left lateral arcuate ligaments provide attachment sites for some of the fibers of the lumbar part of the diaphragm.
