Sexual Response

© Cambridge University Press 2017. PROLOGUE The first reports of the measurement of physiological responses during sexual activity date back to the late 1800s. For example, Mendelsohn (1896) described “pulse curves” (EKGs) during sexual intercourse. Such early explorations were followed by more systematic attempts to understand the physiology of sexual response, as exemplified by the writings of Van de Velde (1926), Dickinson (1933), and Kinsey and colleagues (Kinsey, Pomeroy, Martin, & Gebhard, 1953). The work of Masters and Johnson (1966), who observed sexual responses in over 650 individuals, served as a foundation for the field of sexual psychophysiology and continues to be the stimulus for much research. Initially, researchers relied on direct observation and the use of non-genital measures such as heart rate, respiration, and sweat gland activity to index sexual arousal. Zuckerman (1971) concluded that extragenital measures were not specific to sexual arousal. Coupled with Masters and Johnson’s (1966) report that genital vasocongestion is the most reliable indicator of sexual response, Zuckerman’s review accounts for the trend in the field toward the development and use of genital response measures. ANATOMY AND PHYSIOLOGY Anatomy Women The external female genital area is known as the vulva, which is rich in nerve endings and heavily vascularized. The labia majora, also known as the outer lips, surround the labia minora, or inner lips, which enclose an area called the vestibule. The labia minora fuse above the vestibule to form the clitoral prepuce and under the vaginal opening form the frenulum. The clitoris is composed of the clitoral head (glans), the clitoral shaft (corpus), and the clitoral legs (crura). The clitoral body consists of two corpora cavernosa. The vestibular bulbs of the crura, also referred to as the clitoral bulbs, appear homologous to the corpus spongiosum in men (O’Connell, Hutson, Anderson, & Plenter, 1998; however, see Puppo & Puppo, 2015). The clitoral shaft becomes engorged with blood during sexual arousal. However, it does not have a subalbugineal layer that would constrict venous outflow. Due to this, the clitoris can become engorged but does not reach levels of rigidity similar to that of the penis. The organ that has been the focus of genital response measurement in women is the vagina. The vagina is a collapsed canal that consists of two layers (Levin, 2003). The innermost layer is made of many transverse folds or “rugae” that provide accordion-like distensibility.edition: 4thstatus: accepte