Many patients with impotence will have the experience that after a series of tests and diagnosis, they are either told that there is insufficient blood supply to the cavernous arteries of the penis, or they are told that they suffer from venous leakage. Both insufficient arterial blood supply and venous leakage are common causes of impotence, collectively known as vascular impotence. Here’s a brief overview of why penile vascular problems can cause impotence. To clearly understand this problem, first of all, we need to understand the structure of the penis: the penis is mainly composed of 3 spongy bodies, of which the main one responsible for erection is the penile corpus cavernosum. Penile corpus cavernosum is like 2 closed water pipes, one left and one right arranged above the urethral corpus cavernosum (called the front of the penis when it is weak), the head end is connected to the coronary groove, and the foot end is connected to the pelvis at the root of the penis. The urethral sponge is crossed by the urethra in the middle and is therefore primarily responsible for urination. (Pictured below). The outer layer of the corpus cavernosum of the penis is surrounded by a tough tunica albuginea, and the inner core is filled with tissues such as the spongy muscles, which form the spongy cavities, which are called cavernous sinuses. The arteries and veins of the penis pass through the tunica albuginea into the corpus cavernosum of the penis (shown below, with the red arrow pointing to the cavernous sinus). The process of penile erection is essentially the process of filling the corpus cavernosum with blood. When an erection is initiated, the arteries of the penis dilate, blood flow increases significantly, blood entering the cavernous body of the penis increases, the cavernous sinus dilates, and the pressure in the sinus rises. (Figure below) As the pressure within the cavernous sinus rises, the cavernous sinus dilates further and increases in volume. Because the stretch of the cavernous body’s white membrane is limited, the veins are squeezed, the veins close (left side of the figure below), and the blood flow out of the cavernous body decreases. The pressure within the cavernous sinus then rises further and the penis becomes erect. Therefore, it is easy to understand that the more the corpus cavernosum is filled with blood the harder the erection will be! It’s like filling an airtight hose, the more water that enters and the better the airtightness, the easier it is for the hose to fill and the higher the water pressure! Penile erection is similar to this, the more arterial blood flow is available at the time of erection initiation, and the more completely the veins are closed, the better the quality of the erection will be! Therefore, the quality and hardness of an erection essentially depends on both the congestion of the corpus cavernosum of the penis and the closure of the veins. When an erection is initiated, the better the arterial blood supply, the more blood enters the corpus cavernosum, and the better the engorgement, the harder it will be. At the same time the venous closure is intact and the blood entering the cavernous sinus is not lost. Only the arterial blood supply is sufficient and the vein closure is intact, both at the same time, the penis will have a satisfactory erection hardness; on the contrary, the penis erection will be weak and feeble! This is why the problem of erection quality is ultimately a problem of vascular function. Any problem that can affect the blood supply to the arteries, or the closure of the veins, either psychologically or through disease, can cause impotence. For example, atherosclerosis caused by congenital arterial stenosis, venous leakage, vascular malformations, trauma, surgery, high blood lipids and diabetes can affect the arterial blood supply to the penis or cause impaired venous closure, which in turn can lead to impotence.