Most of the lymph vessels of the penis (including the M. ischiocavernosus and M. bulbocavernosus) and the glans (including the visceral layer of the prepuce) drain to the superficial inguinal lymph nodes, while a smaller number drain to the lateral sacral and hypogastric lymph nodes. A description of their detailed behaviour follows:
The lymph vessels of the glans, including the visceral layer of the prepuce (Figure 32: t), form extraordinarily fine networks in the visceral layer of the prepuce covering the glans. The lymph vessels which develop from these networks run either in the visceral layer or just under it to the base of the preputial sac, which lies immediately caudal to the bulbus glandis. Here, the lymph vessels emerge from under the visceral layer and continue to run caudally close to the penis, usually on its dorsum, though some may also run on its lateral surfaces, to drain to the superficial inguinal lymph nodes (Figure 32: 4). Before reaching the lymph nodes, most of the lymph vessels run caudally past them, often as far as the vicinity of the ischial arch, before turning again in a cranial direction towards the lymph nodes; due to this pattern, they form large, caudally extended loops, which are shown in Figure 32.
The lymph vessels of the penis (Figure 32: s) join with the lymph vessels of the glans and drain with them to the superficial inguinal lymph nodes. The lymph vessels of the crus penis, including the M. ischiocavernosus (Figure 32: r) and the M. bulbocavernosus (Figure 32: q), take one of two paths: some of these lymph vessels join with the lymph vessels of the penis, as shown in Figure 32, and drain with them to the superficial inguinal lymph nodes (Figure 32: 4), while others (1 to 2 vessels) enter the pelvic cavity and run subperitoneally along the lateral pelvic cavity wall to drain to the hypogastric lymph nodes (Figure 32: 3). If a lateral sacral lymph node (Figure 32: 5) is present, one of these lymph vessels will usually enter this node first.
Direct drainage of the lymph vessels to the medial iliac lymph nodes was not observed in 4 more closely examined cases.
The lymph vessels of the penis form extensive networks in the tunica albuginea of the penis.