Introduction and Gross Anatomy
The vagina is a functional organ of the female reproductive organ system. It extends from the vulva externally to the uterine cervix internally and is located within the pelvis, anterior to the rectum and posterior to the urinary bladder.
The vagina lies at a 90° angle in relation to the uterus and is held in place by endopelvic fascia and ligaments. It is a potential space that is easily distended.
The vaginal lining is called rugae, which are situated in folds throughout. These allow for distention, especially during childbearing and coitus. The structure of the vagina is a network of connective, membranous, and erectile tissues.
The sphincter urethrae and the transverse perineus muscles, perineal membrane, and pelvic diaphragm support the vagina. The term urogenital diaphragm is no longer used; formerly, it included the sphincter urethrae and the deep transverse perineus muscle, together with their inferior fascia, the perineal membrane. These muscles are innervated by perineal branches of the pudendal nerve. The pelvic diaphragm primarily refers to the levator ani and coccygeus muscles and is innervated by branches of S2-S4 from the sacral plexus.
Vasculature, Nerve Supply, and Lymphatic Drainage
The vasculature of the vagina is supplied primarily by the vaginal artery, a branch of the anterior division of the internal iliac artery. Several of these arteries may be found on either side of the pelvis to richly supply the vagina.
The nerve supply to the vagina is primarily from the autonomic nervous system. Sensory fibers arise from the pudendal nerve, and pain fibers are from sacral nerve roots.
Lymphatic drainage of the vagina is generally to the external iliac nodes (upper third of the vagina), the common and internal iliac nodes (middle third), and the superficial inguinal and perirectal nodes (lower third).
Disorders of Pelvic Support
The American Urogynecologic Society has published various scholarly works based on cadaver dissections that describe the normal and abnormal anatomic relationships and quantification of defects that involve different structures of human female pelvic support and continence mechanisms.