How an erection happens

Getting and keeping an erection is  straightforward, a simple physical process; it is all the stuff going on in your head that can get in the way.

You have two cylindrical balloons of tissue which run the length of either side of your penis called the Corpora cavernosa. Like sponges, they are capable of filling with blood. When the penis is soft, the muscle fibres in them are contracted. A third cylinder of tissue runs between these called the Corpus spongeosum, This contains the urethra, through which urine and semen pass out of your body. It thickens towards the tip of the penis to form the helmet-shaped glans, which is covered by foreskin in uncircumcised men

Penis lateral cross section

The Tunica is a tough outer sheath that surrounds the corpora and limits the amount they can expand. As the tunica becomes tight, blood flowing into the penis raises the pressure within it, making it hard – It all starts with stimuli, sexual excitement, real or imagined. Inside your mind you have an area called the para-ventricular nucleus; sexual stimuli increases signal output from this area which travel through special autonomic nerves in the spinal cord, the pelvic nerves and the cavernous nerves that run along the prostate gland to reach the corpora cavernosa and to the arteries that supply them with blood.

In response to these signals, the muscle fibres in the corpora cavernosa relax, allowing blood to fill the spaces within them. Muscle fibres in the arteries that supply the penis also relax, and there is an eight-fold increase in blood flow to the penis. The increased blood flow expands the spaces in the corpora, then stretches the surrounding sheath (the tunica). As the tunica stretches, it blocks off the veins that take blood away from the corpora cavernosa. This traps blood within the penis, the pressure becomes very high and the penis becomes erect.

An Erection Is About Blood Pressure.

During an erection, pressure in the penis is at least twice the pressure of blood in the main circulation. This is possible because the muscles of the pelvic floor contract around the base of the corpora cavernosa. At orgasm, the signalling from the brain changes dramatically. There is a sudden increase in noradrenaline production from nerves in the genitalia. This seems to both trigger orgasm and contract the muscle fibres in the corpora cavernosa and their supplying arteries. As a result of this the blood flow into the penis reduces. The pressure within the corpora drops, which also relaxes the tunica and so allows blood to flow out of the penis. This allows the penis to become flaccid again.

That is a process every male is born with, we don’t have to think about it, it just happens. Every 12 year old boy knows the wonder of it ‘just happening’. It’s as adults when we get all complicated about it. When our thinking, beliefs and feelings get in the way. When the problem is in your head and your doctor cannot point to a physical cause, contact me. 0208 647 7441