The perineal area can be divided into two triangles: the anterior (synonym: urogenital) triangle and the posterior (synonym: anal) triangle. The base of both triangles is the superficial transverse muscles. The lateral borders of the anterior triangle are the ischiocavernosus muscles. The lateral borders of the posterior triangle is the sacrotuberous ligament. The anterior triangle contains the root of the scrotum and penis in males and the vulva in females and it extends from the transverse perineal muscle to the pubic symphysis. The posterior triangle contains the anal canal and its external orifice – the anus – and it extends from the transverse perineal muscle to the coccygeal bone.
The borders of the anterior perineal triangle are the ischiocavernosus and the superficial transverse muscles – which are depicted in orange. The borders of the posterior perineal triangle are the superficial transverse muscles and the sacrotuberosus ligaments (blue color).
