Male Erection

The erection, whether it is erection of the penis, clitoris or nipple, depends on the complex interaction of a number of psychological, endocrine, neural and vascular factors.

Male erection refers to the enlarged and firm state of the penis. The erection of the penis occurs when the two corpora cavernosa (the two tubular formations that run along the length of the penis) become engorged with blood. As a result the penis hardens and grows larger.

Penis erection is usually a result of physiological sexual stimulation, but can also occur spontaneously during the course of the day, during erotic dreams at night (known as "nocturnal penile tumescence"), or as a result of a full urinary bladder. The achieving and maintaining of penis erection is crucial to sexual intercourse for males.

How Is the Penis Erection Achieved?

Physiologically, the penis erection is achieved due to increased flow of blood to the penis and significantly decreased outflow. The erectile tissues are engorged with blood and press against the veins that serve to carry the blood away from the penis, constricting those veins and allowing more blood to enter than leave.

When penis erection is achieved the penis stiffens, expands in both length and girth, and rises to a certain angle. The shape and angle of the penis can vary from one man to another, ranging from a straight penis angled at a 45 to 90 degree, to a tightly curved penis to any direction.

Sometimes men fail to achieve erection and the reasons may be either physiological or psychological or both.

When physical stimuli are applied the male erection is initiated by the parasympathetic nervous division of the autonomic nervous system. When no direct mechanical stimulation is applied, erection can be still initiated in response to visual, auditory, or olfactory stimuli by the cerebral cortex. The cortex can also suppress penis erection even in the presence of direct stimulation, for example under conditions of stress.

The inability to achieve and/or maintain penis erection is known as erectile dysfunction (ED), or impotence.