Blood vessels and nerves of the human penis.

The spongy tissue of the penis together with the arteries and veins functionally becomes an erectile system because these structures are surrounded by layer of collagenous and elastic fibers capable to withstand blood pressure and to stretch. The caliber of the terminal branches of the arteries inside the spongy tissue is modified due to the presence of epitheloid cells and smooth muscle cells. The veins drain the blood into three main regions: the femoral region, the deep pelvic region and the upper pelvic region. The penile nerves enter the ilioinguinal nerves, the perineal nerves, the dorsal penile nerve and the pudendal nerves. These afferent fibers terminate in the spinal cord (Th 12-S 4). The parasympathetic and sympathetic fibers run together with the pudendal nerves and arise in S 2-S 4 or Th 12-L 1. Both the pudendal nerves and the hypogastric ganglia must be carefully spared in the course of all surgical procedures.