Functions and features of the male urethra
The main function of the urethra (urethra) is to excrete urine accumulated in the urinary bladder cavity into the external environment. However, the male urethra (urethra masculina) has an important physiological feature: it is integrated into the male reproductive system (organa genitalia masculina).
Due to this, the organ bears a dual load, ensuring not only the act of urination but also the process of ejaculation. For comparison, the female urethra (urethra feminina) is significantly shorter and wider, and its physiological role is strictly limited to the excretion of urine.
Anatomical segments
The male urethra is a relatively long structure. Its total length in an adult reaches about 20–23 cm. Topographically, the canal is subdivided into several successive segments along its course:
- Intramural part (pars intramuralis) — the initial segment.
- Prostatic part (pars prostatica) — passes through the thickness of the prostate gland.
- Membranous part (pars membranacea) — the shortest and narrowest section.
- Spongy part (pars spongiosa) — the longest segment.
Structure of the wall and mucosa
The wall of the urethra has a layered structure and consists of three main components:
- Mucous membrane — lines the lumen of the canal.
- Muscular layer — provides tone and contractility.
- Connective tissue elements — form the supporting framework.
The relief of the mucous membrane is heterogeneous. Its surface forms characteristic folds, as well as depressions (lacunae) and dilations, which is important for the dynamics of fluid passage.
Sphincter apparatus
Urinary continence and control over the urination process are ensured by special muscular structures — sphincters. According to anatomical data, in the region of the membranous part (pars membranacea), as well as in the area of the external urethral orifice, lies the external urethral sphincter (m. sphincter urethrae externus). It consists of striated muscle and is subject to voluntary control.
Briefly: answers to topical questions
What anatomical constrictions and dilations are distinguished along the male urethra?
Alternating narrowed areas and dilations are distinguished along the length of the male urethra.
- Constrictions — the membranous part (pars membranacea) is the narrowest and shortest part of the urethra.
- Dilations — the prostatic part (pars prostatica), the bulbous part (pars bulbosa), which is the widest segment, and the navicular fossa in the area of the glans penis.
What bends does the male urethra form along its course?
Along its course, the male urethra forms two bends.
- Upper (subpubic) bend — formed at the transition of the membranous part into the spongy part, its concavity is directed forward and upward.
- Lower (prepubic) bend — formed at the transition of the fixed part of the urethra into the mobile part, its concavity is directed downward.
When the penis is pulled toward the anterior abdominal wall, both anatomical bends merge into a single common one with its concavity directed forward and upward, which allows the introduction of straight metal instruments during catheterization.
Which sphincters provide urinary continence and control over urination in men?
Urinary continence is provided by two sphincters that are in a tonic state.
- Internal urethral sphincter (m. sphincter urethrae internus / m. sphincter vesicae) — involuntary, formed by smooth muscle. It is located in the area of the bladder neck and surrounds the initial segment of the urethra.
- External urethral sphincter (m. sphincter urethrae externus) — voluntary, formed by striated muscle. It is located at the level of the membranous part of the urethra.
The ducts of which glands open into the lumen of the male urethra?
The excretory ducts of several glands of the reproductive system open into the lumen of the male urethra.
- Prostate gland (prostata) — its excretory ducts open into the prostatic urethra on the sides of the seminal colliculus.
- Bulbourethral (Cowper's) glands (glandulae bulbourethrales) — the ducts of these paired glands open into the proximal bulbous part of the spongy urethra.
In addition, the ejaculatory ducts, formed by the merger of the ducts of the seminal vesicles and the terminal parts of the ductus deferentes, open on the seminal colliculus in the prostatic part.
From which arteries is the blood supply to the various parts of the male urethra carried out?
The blood supply to the male urethra is carried out mainly by the internal pudendal artery (a. pudenda interna).
Which nerves provide innervation to the male urethra?
Innervation of the male urethra is derived from the pudendal plexus. The sphincteric apparatus of the urethra is in a tonic state due to sympathetic and somatic innervation; the external sphincter, formed by striated muscle, is voluntary.
To memorize the four parts of the male urethra, use the phrase: "Intramural, Prostatic, Membranous, Spongy".
Class and exam questions
How does the male urethra functionally differ from the female urethra?
The male urethra combines the functions of excreting urine from the bladder and ejaculation, whereas the female urethra (shorter and wider) serves exclusively for urination.
What is the average length of the male urethra?
In an adult male, the length of the urethra is about 20–23 centimeters.
Where is the external urethral sphincter located?
The external urethral sphincter (m. sphincter urethrae externus) is localized in the region of the membranous part and the external orifice.
What elements form the wall of the urethra?
The urethral wall consists of a mucous membrane (forming folds and lacunae), a muscular layer, and connective tissue elements.
What else to study on this topic
- Topography of the prostatic part (pars prostatica) and its connection with the ejaculatory ducts
- Anatomy of the spongy part (pars spongiosa) in the structure of the penis
- Mechanism of action of m. sphincter urethrae externus
- Features of the mucosal relief: lacunae and dilations of the male urethra
- Comparative anatomy of the male and female urethra
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