The regulation of vascular and trabecular smooth muscle relaxation or contraction in the penis, that is, the physiology of corporal smooth muscle tone, determines penile erection or flaccidity.

• 阴茎海绵体平滑肌舒张或收缩的调节,即海绵体平滑肌紧张性的生理学分别决定阴茎的勃起或疲软状态。