Physiology and Pathophysiology of Female Sexual Function

This chapter focuses on the physiology of the female sexual response cycle and innervation of female sexual function. Sexual arousal causes increased pelvic blood flow, genital vasocongestion, vaginal dilatation and lengthening, engorgement of the labia minora and tissue surrounding the urethral lumen, clitoris and vestibular bulbs. Afferent arousal pathways include several sensory systems, as well as visual and olfactory stimuli. Stimuli from the pudendal, pelvic hypogastric, and genitofemoral nerves contribute to arousal. Prolactin causes sexual satiety, reduces libido and gonadal function, offsets central dopamine effects after orgasm and correlates with postorgasmic sexual satiety and relief. Descending motor impulses innervate rhabdosphincters and striated pelvic floor muscles and thus contribute to male and female sexual responses. Progesterone seems to further receptivity to partner approach. Estrogens are vasoprotective and support female sexual response by enhancing desire, arousal, nerve transmission, sensory thresholds, vaginal, clitoral and urethral arterial blood flow. Bulbocavernosus reflex testing or pudendal nerve somatosensory evoked potentials and tests such as pudendal nerve distal motor latencies or central motor conduction time to pelvic floor muscles are useful in suspected central, spinal, or peripheral motor pathway lesions.