hi its not a n muscle as such as its blood that keeps it erect but if you go to www. pegym. com and click on penis exercises your find just doing some of then like jelqing and stretching will help you a lot chuck in some kegels and your away for life. but do follow what the tell you to do do go in blind read up it all first try reading down the forums as well. hope this helps your penis. good luck
is the penis considered a muscle that needs exercise to remain "healthy".