Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Urogenital system
Urinary (excretory) system
Urethra

The female urethra is a short tube, 3–6 cm in length, located posterior to the Pubic Symphysis. Its mucous membrane is lined with pseudostratified epithelium. The myocytes in the urethral wall form two layers: an inner longitudinal layer and a more prominent outer circular layer. The external urethral orifice is situated anterior and superior to the vaginal opening and is encircled by striated Muscle fibers. Bundles of these fibers form the external urethral sphincter.

The male urethra is a narrow tube measuring 16–22 cm in length in an adult. It consists of three parts: the prostatic part, passing through the Prostate Gland; the membranous part, the shortest segment, passing through the urogenital Diaphragm; and the spongy part, the longest segment, embedded within the corpus spongiosum of the Penis. Along its course, the urethra forms two curvatures. The upper curve presents a concavity directed anteriorly and superiorly, located within the prostatic and membranous PARTS OF THE urethra. The lower curve presents a concavity directed inferiorly and posteriorly, located at the junction of the fixed and free parts of the penis. On the posterior wall of the prostatic urethra lies a longitudinal elevation, the urethral crest, featuring the seminal colliculus, flanked by the openings of the ejaculatory ducts and the ducts of the prostate gland.

The mucous membrane in the initial segment of the urethra is lined with transitional epithelium. Approaching the membranous part, it transitions to columnar epithelium. At a distance of 5–6 mm from the external urethral orifice, the epithelium becomes stratified squamous. The lamina propria of the urethral mucosa contains numerous small mucous glands. Surrounding the membranous part of the urethra, the striated Muscles of the urogenital diaphragm form the external (voluntary) urethral sphincter.



Last update: 10/08/2026

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