Lumbosacral Trunk

Lumbosacral trunk is the nerve trunk that connects the lumbar plexus and the sacral plexus. It is composed of the whole of the anterior ramus of 5th lumbar nerve and part of the anterior ramus of 4th lumbar nerve. The trunk appears at the medial margin of the psoas major and enters the pelvis by passing down in front of the sacroiliac joint and joins the anterior ramus of first sacral nerve.