It is our belief that sexual dysfunction is a common condition affecting both men and women. Many practitioners, particularly in the disciplines of family practice, internal medicine, and urology, may have the opportunity to treat both male and female patients, sometimes even the husband and wife of a family. In such instances, sexual dysfunction may be occurring in both partners. For that reason, we decided to present information regarding the pathogenesis, diagnosis, and treatment of sexual dysfunction in men and women in the same book. The book is well supplemented with tables and timely references. Any practitioner who deals with both male and female patients with sexual problems will find this book to be useful. Introduction
■ Penile erection is the result of increased penile inflow of blood and reduced outflow.
• Arterial inflow of blood to the penis is coupled with vasodilation of the cavernosal and helicine arteries.
• This results in blood filling the sinusoidal spaces of the corpora cavernosa. • This leads to expansion of the lacunar spaces and tunica albuginea.
■ Neural control of erection involves a shift from sympathetic tone to parasympathetic tone.
■ The neural circuitry for erection is based in the spinal cord.
■ Role of Spinal Cord and Neural Innervation of the Penis
■ The penis receives autonomic innervation from the sympathetic and parasympathetic nervous systems.
■ Both systems contain nuclei located in the spinal cord.
■ The parasympathetic nervous system is excitatory for erectile function. • Preganglionic parasympathetic neurons arise from the sacral spinal cord segments S2–S4. • The major segment contributing to erectile function is S3.
■ The sympathetic nervous system is inhibitory to erectile function. • However, because of its vasoconstrictive properties, some fibers have a role in pelvic vasoconstriction, which may increase blood flow to the penis to promote erection.