Male and female urethra - description, its parts, hypospadia

The urethra 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.

In this article, we shall look at the anatomy of the male and female urethra – their anatomical course, neurovascular supply, and any clinical correlations.

Male Urethra

The male urethra is approximately 15-20 cm long. In addition to urine, the male urethra transports semen.

Male Urethra

The male urethra can be divided anatomically into three parts (proximal to distal):

• Prostatic urethra:
  • Begins as a continuation of the bladder neck and passes through the prostate gland.
  • Receives the ejaculatory ducts (containing spermatozoa from the testes and seminal fluid from the seminal vesicle glands) and the prostatic ducts (containing alkaline fluid).
  • It is the widest and most dilatable portion of the urethra.

• Membranous urethra:
  • Passes through the pelvic floor and the deep perineal pouch.
  • Surrounded by the external urethral sphincter – which provides voluntary control of micturition.
  • It is the narrowest and least dilatable portion of the urethra.

• Penile (bulbous) urethra:
  • Passes through the bulb and corpus spongiosum of the penis, ending at the external urethral orifice (the meatus).
  • Receives the bulbourethral glands proximally.
  • In the glans (head) of the penis, the urethra dilates to form the navicular fossa.

Neurovascular Supply

The arterial supply to the male urethra is via several arteries:

• Prostatic urethra – supplied by the inferior vesical artery (branch of the internal iliac artery which also supplies the lower part of the bladder).
• Membranous urethra – supplied by the bulbourethral artery (branch of the internal pudendal artery)
• Penile urethra – supplied directly by branches of the internal pudendal artery.

The nerve supply to the male urethra is derived from the prostatic plexus, which contains a mixture of sympathetic, parasympathetic and visceral afferent fibres.

Lymphatic Drainage

Lymphatic drainage also varies according to the region of the urethra. The prostatic and membranous portions drain to the obturator and internal iliac nodes, while the penile urethra drains to the deep and superficial inguinal nodes.

Female Urethra

In females, the urethra is relatively short (approximately 4 cm). It begins at the neck of the bladder, and passes inferiorly through the perineal membrane and muscular pelvic floor. The urethra 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 2-3 cm 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 – Skene’s glands. They are homologous to the male prostate.

Neurovascular Supply

The arterial supply to the female urethra is via the internal pudendal arteries, vaginal arteries and inferior vesical branches of the vaginal arteries. Venous drainage is given by veins of the same names.

The nerve supply to the female urethra arises from the vesical plexus and the pudendal nerve. Visceral afferents from the urethra run in the pelvic splanchnic nerves.

Lymphatic Drainage

Lymphatic drainage of the proximal female urethra is to the internal iliac nodes, while the distal urethra drains to the superficial inguinal lymph nodes.

Hypospadias

Hypospadias is a condition where the urethra and foreskin don’t develop properly in a baby’s penis.

Early in a fetus’s development, the urethra starts as an open channel. The channel closes to form a complete tube as a fetus develops before birth. The meatus is the opening at the end of the urethra. It’s usually in the head of or at the tip of the penis.

In a baby with hypospadias, the urethral tube doesn’t close all the way, causing the meatus to form below the tip of the penis. It may exist anywhere along the shaft of the penis, in the scrotum or even lower, near the anus.

Hypospadias is a congenital condition. It can range from mild to severe. Without treatment, problems can develop later in life, including difficulty urinating and difficulties having sexual intercourse.

https://my.clevelandclinic.org/health/diseases/15060-hypospadias https://teachmeanatomy.info/pelvis/viscera/urethra/