Pediatric Surgery, Al Azher University, Cairo, Egypt
A broad overview of the normal anatomy of the male genitalia is essential to offer the best surgical outcomes in dealing with cases related of congenital abnormalities, trauma, and aesthetics penile reconstruction. Neural and vascular anatomy is discussed in depth due to its critical role in maintaining function and in assuring tissue viability during penile reconstructive surgery.
KeywordsPenile innervationPenile vasculatureCorpora spongosiumUrethraTunica AlbugineaBuck’s fasciaFrenulum of prepuce of penis
The development of the human penis is a complex sequence of events which results in an utterly individual outcome: no two penises are identical and there is a surprising range of anatomical detail that should be considered normal. Parents need to be assured of this range of normality. Moreover, the desire of practitioners for standard procedures can lead to unpredictable outcomes because of both this anatomical variation and the impossibility of predicting the functional results of surgical correction in infants. This is because the procedures are performed with an emphasis on achieving an acceptable cosmetic outcome on a very small organ which has the capacity for considerable growth and changes during puberty. Furthermore, no surgical procedure can have absolutely predictable outcomes because of the variations in healing and scar formation, the individual variations in technique, and the effects of infection. Regrettably, it seems that the majority of those performing surgical procedures on the penis of minors take no interest in following up the outcome after the organ has developed. (See Chap. 35, Complications of Circumcision) (Fig. 2.1).
2.2 Penile innervation (Fig. 2.2)
Transverse cut section of the penis
Penile innervation consists of the dorsal, cavernosal, and perineal nerves. Dorsal nerves arising from the pudendal nerves travel within Buck’s fascia, together with the dorsal arteries and veins, to supply sensation to penile skin. Despite its nomenclature, it is important to note that the nerves do not lie directly in the dorsal midline, but rather extend from the 11 and 1 o’clock positions laterally to the junction of the cavernosa and spongiosum. These nerves do not send perforators deep through the tunica albuginea to the corpora cavernosa. There is a paucity of nerves at the 12 o’clock shaft position. Therefore, in correction of penile curvature, plication at the 12 o’clock position is the area least likely to result in nerve damage. Like the dorsal nerves, the perineal nerves also arise from the pudendal nerve to supply the ventral shaft skin, the frenulum, and the bulbospongiosus muscle. The cavernosal nerves arise from the autonomic pelvic plexus and travel along the periprostatic neurovascular bundle, well known to urologists performing radical retropubic prostatectomies. Underneath the pubic arch, the cavernosal nerves pierce through the corpora cavernosa. Proximal to this point, the cavernosal and dorsal nerves lie within close proximity at the penile hilum and are thought to exchange signal communication, which may have implications on erectile function. As well, there are interactions between perineal and dorsal nerves laterally at the junction of the cavernosa and spongiosum along the penis, which may also have implications on erection and ejaculation .
2.3 Penile Vasculature
There are three paired main arteries in the penis: cavernosal, dorsal, and bulbourethral. All three arise from a shared branch of the internal pudendal artery, which itself arises from the internal iliac artery. On each side, the first branching occurs at the bulb of the spongiosum external to the urogenital diaphragm forming the bulbourethral artery, which then lies at the 9 and 3 o’clock positions of the corpus spongiosum. Then the cavernous artery branches to penetrate the corpora cavernosa and the remainder of the artery continues as the deep dorsal artery. The deep dorsal artery causes glans enlargement during erection, whereas the cavernosal arteries cause corporal enlargement. All three arteries communicate distally near the glans to provide an extensive anastomotic network.