Vaginal Cancer 20.1 Anatomy

Abstract

The vagina is a muscular tubular structure approximately 7.5 cm in length that extends from the cervix to the vulva. It lies dorsal to the base of the bladder and urethra and ventral to the rectum. At its upper most extent, the vaginal wall attaches to the uterine cervix at a higher point on the posterior wall that is on the anterior wall. The vaginal wall is composed of three layers: the mucosa, muscularis and adven-titia. The inner mucosal layer is formed by a thick, nonkeratinizing, stratifi ed squa-mous epithelium overlying a basement membrane containing many papillae. Beneath the mucosa lies a submucosal layer of elastin and a double muscularis layer, highly vascularized with a rich innervation and lymphatic drainage. The adventitia is a thin, outer connective tissue layer that merges with that of adjacent organs. The proximal vagina is supplied by the vaginal artery branch from the uterine or cervical branch of the uterine artery. It runs along the lateral wall of the vagina and anastomoses with the interior vesical and middle rectal arteries from the surround-ing viscera [ 1 ]. The accompanying venous plexus, running parallel to the arteries, ultimately drains into the internal iliac vein. The lumbar plexus and pudendal nerve provide innervation to the vaginal vault. The lymphatic drainage of the vagina is complex. The lymphatics in the upper portion of the vagina drain fi rst of all via the lymphatics of the cervix. The distal vagina lymphatics follow drainage patterns of the vulva into the inguinal and femo-ral nodes and from there to the pelvic nodes [ 2 ]. Owing to the presence of intercom-municating lymphatics along the terminal branches of the vaginal artery and near 488 the vaginal wall, the external iliac nodes are at high risk even in lesions of the lower third of the vagina. Bilateral pelvic nodes should be considered at risk in any inva-sive vaginal cancers [ 3 ]. Approximately 50 % of women who had lesions in the upper third of the vagina were found to have a sentinel node in the inguinofemoral region when anatomic site would predict for involvement of pelvic lymph nodes.