Urethra Flashcards
what is the uretra
is the vessel responsible for transporting urine from the bladder to an external opening in the perineum. It is lined by stratified columnar epithelium, which is protected from the corrosive urine by mucus secreting glands.
desirbe the male uretra
The male urethra is approximately 15-20cm long. In addition to urine, the male urethra provides an exit for semen (a fluid containing spermatozoa and sex gland secretions).
Anatomically, the urethra can be divided into four parts:
Pre-prostatic (intramural): Begins at the internal urethral orifice, located at the neck of the bladder. It passes through the wall of the bladder, and ends at the prostate.
Prostatic: Passes through the prostate gland. The ejaculatory ducts (containing spermatozoa from the testes, and seminal fluid from the seminal vesicle glands) and the prostatic ducts drain into the urethra here.
Membranous: Passes through the pelvic floor, and the deep perineal pouch. It is surrounded by the external urethral sphincter, which provides voluntary control of micturition.
Spongy: Passes through the bulb and corpus spongiosum of the penis, ending at the external urethral orifice. In the glans penis, the urethra dilates, forming the navicular fossa. The bulbourethral glands empty into the proximal urethra
desirbe the female uretra
In women, the urethra is relatively short (approximately 4cm). This predisposes women to urinary tract infections.
The urethra begins at the neck of the bladder, and passes inferiorly through the perineal membrane and muscular pelvic floor. It opens directly onto the perineum, in an area between the labia minora, known as the vestibule. Within the vestibule, the urethral orifice is located anteriorly to the vaginal opening, and 2-3cm posteriorly to the clitoris.
The distal end of the urethra is marked by the presence of two mucous glands that lie either side of the urethra. These glands are homologous to the male prostate.
