The terminal part of the male urethra is called. Male urethra. Diseases in women and men

MALE URINARY CHANNEL

Male urethra (male urethra),uret­ hra masculina, - unpaired organ, has the shape of a tube with a diameter of 0.5-0.7 cm and a length of 16-22 cm; perforates the prostate gland, urogenital diaphragm and corpus spongiosum of the penis (see Fig. 9). The male urethra is used to remove urine and eject semen. Begins with the internal opening of the urethra, ostium urethrae inter-Pete, in the wall of the bladder and ends with the external opening, ostium urethrae exiernum, located on the head of the penis. Topographically, the male urethra is divided into three parts: prostatic, membranous and spongy, and from the point of view of mobility - into fixed and mobile. The boundary between the latter is the place of attachment to the penis of the sling-shaped ligament of the penis.

prostate part, pars prostdtica, has a length of about 3 cm, passes in a vertical direction through the prostate gland. The lumen of the male urethra in the middle part of the prostate is expanded. On the posterior wall of the prostatic part of the urethra there is an oblong elevation - the crest of the urethra (urethra), crista urethralis. The most prominent part of this ridge is called the seminiferous hillock, or seminal tubercle, colliculus semindlis, at the top of which there is a depression - the prostatic uterus, utriculus prostdticus, being a rudiment of the terminal section of the paramesonephric ducts. The orifices of the ejaculatory ducts open on the sides of the prostatic uterus. Around the circumference of the seminal mound itself there are openings of the excretory ducts of the prostate gland.

membranous part, pars membrandcea, extends from the apex of the prostate gland to the bulb of the penis (see Fig. 9). This section is the shortest (up to 1.5 cm) and narrowest. Where the membranous portion passes through the urogenital diaphragm, the male urethra is surrounded by concentric bundles of striated

muscle fibers that form the voluntary sphincter of the urethra, T.sphincter urethrae.

The longest (about 15 cm) part of the male urethra is the spongy part, pars spongiosa. In the area of ​​the bulb of the penis, the male urethra expands somewhat, but throughout the rest of its length its diameter is constant. The final section of the male urethra, located in the head of the penis, expands again, forming the scaphoid fossa of the urethra, fossa naviculdris urethrae.

The male urethra ends on the head of the penis with an external opening, which has little extensibility, since there is a fibrous-elastic ring in the wall of the canal. Along its path, the male urethra is S-shaped and has 3 narrowings: in the area of ​​the internal opening of the urethra, when passing through the urogenital diaphragm and at the external opening. Enlargements of the lumen of the male urethra are present in the prostate part, in the bulb of the penis and in its final section - the scaphoid fossa.

The mucous membrane of the male urethra contains a large amount of glands,gll. urethrdles (Littre's glands), opening into the lumen of the canal. In the spongy part of the urethra there are small, blindly ending depressions - lacunae (crypts), lacunae urethrales. Outside the mucous membrane, the wall of the male urethra consists of a submucosa and a muscular layer, represented by longitudinal and circular layers of smooth (non-striated) muscle cells.

Urinary channel- a gap 5-6 cm wide, delimited from surrounding tissues by the mucous membrane and muscular-elastic elements. It starts from the neck of the bladder with an internal opening and ends at the head of the penis with an external opening between two longitudinally located sponges. Urinary the channel serves to remove urine, as well as secretions of the gonads. It has fixed (posterior) and movable (anterior) sections. On my way urinary the canal passes through various formations, therefore it is anatomically divided into intravesical, membranous, prostatic and spongy parts. The intravesical section, located in the thickness of the wall of the bladder (its length is 0.5-0.6 cm), is covered with a mucous membrane containing multilayered epithelium, the nature of the structure approaching the mucous membrane of the bladder. It is surrounded by a layer of smooth muscle fibers that form the internal sphincter urinary canal," or sphincter of the bladder. K intravesical department directly adjacent to the prostatic part of the canal, which is the widest area and has a length of about 3-3.5 cm. On its back wall, approximately in the middle, there is an eminence (seminal mound), on which two openings of the ejaculatory ducts and the opening of the male uterus, which occupies the central part of the seminiferous mound, open.

On the sides of the seminal mound there are multiple openings through which the excretory ducts of the prostate gland open.

The mucous membrane of the prostate gland of the urethra forms longitudinal folds, and its epithelium passes into the epithelium of the ducts and glandular ducts of the prostate gland. The muscular layer of this part of the canal is closely connected with the muscle tissue of the prostate gland and bladder.

The prostatic part passes into the narrowest membranous section urinary canal, 1.5-2 cm long, which penetrates the urogenital diaphragm 2 cm behind the pubic bones. The thickness of the wall of the membranous section is about 2 cm. It has longitudinal and circular layers of smooth muscle fibers and is surrounded by bundles of striated muscles emanating from the deep transverse muscle, forming the external voluntary sphincter, or urethral sphincter. The membranous section is firmly fixed and, together with the prostate, forms a fixed posterior section urinary channel

After the membranous, the spongy, anterior, movable section begins, about 17-20 cm long. There are bulbous and hanging sections, which pass through the corpus spongiosum. In the bulbous section (its length is about 7-8 cm) urinary the canal expands again, and the ducts of multiple glands of the mucous membrane (Littre’s glands) and the ducts of two onion-urethral (Cooper) glands open into it. Next, the bulbous section of the spongy section of the urethra passes into the pendulous section (length 10-12 cm), the distal part of which passes through the head of the penis and is called the capitate section. There is a gap in this final section urinary The canal expands to 0.8-1.0 cm, forming a scaphoid fossa, which is a rudiment of the vagina and is lined with stratified squamous epithelium. The mucous membrane of the rest of the spongy urethra does not have a submucosal layer and is covered with single- and multilayer prismatic epithelium; there are lacunae on its anterior surface urinary canal (Morgagni lacuna), where the paraurethral glands open. The urethra in men has two bends: the first (permanent), prepubic, concave down, encircling the symphysis, and the second (non-permanent), subpubic, concave upward, formed when the fixed part passes into the movable part. The subpubic bend disappears when the penis is abducted to the anterior abdominal wall.

Thus, along the way urinary canal there is an alternation of anatomical narrowings and expanded areas. The anatomical narrowings of the urethra are the external opening of the urethra, the membranous (external sphincter) and intravesical (internal sphincter) sections. Dilated areas in the urethra are considered to be the scaphoid fossa, bulbous dilation and prostate. The lower wall of the anterior urethra, down to the membranous part, can be palpated. Clearance urinary channel is constantly in a dormant state. Only the passage of urine and ejaculation straighten its walls.

The blood supply comes from the branches of the internal iliac artery, the continuation of which is the internal pudendal artery; the prostate part is fed by the rectal artery and the inferior cystic artery; membranous - inferior rectal and perineal arteries. Spongy department urinary The canal is supplied with blood by the branches of the internal pudendal artery - the urethral, ​​as well as the dorsal and deep arteries of the penis.

Venous drainage occurs through the veins of the penis to the veins of the bladder.

Lymphatic drainage from the prostatic and membranous parts of the urethra occurs to the vessels of the prostate gland, to the internal iliac nodes, and from the spongy part of the urethra to the inguinal lymph nodes.

Sensory innervation urinary the canal is provided by the branches of the dorsal genital and perineal nerves, the autonomic one - from the prostatic plexus of the inferior epigastric nerve.

Physiology urinary channel In men it changes with age. Before puberty, the canal is shorter, narrower and has a bend in the posterior section. After puberty with the enlargement of the penis and the development of the prostate gland, the urethra is finally formed. In old age, with prostatic hypertrophy, the prostate changes urinary channel and its lumen decreases.

Urinary the channel performs three functions: it holds urine in the bladder; carries it out when urinating; removes sperm at the moment of ejaculation. Urine retention in the bladder is accomplished by the internal (involuntary) and external (voluntary) sphincters. When the bladder is full, the main role is played by the powerful external voluntary sphincter; contraction also helps to retain urine. muscle mass prostate gland.

Urination is a complex reflex-voluntary act. When intravesical pressure reaches a certain level (when the volume of urine in the bladder is over 200 ml), the urge to urinate appears. Under the influence of a volitional impulse, the muscles of the bladder and abdominal wall contract, with simultaneous relaxation of the sphincters, and the bladder is emptied.

The passage of sperm through the urethra occurs at the moment of ejaculation.

Ejaculation is a reflex act in which one takes an active part urinary channel and all formations associated with it. In this case, the internal sphincter (bladder sphincter) contracts, which, together with the seminal mound that swells during erection, prevents ejaculate from being thrown into the bladder. At the same time, the external sphincter (sphincter urinary canal), and there is a sequential emptying of the contents of the epididymis, vas deferens, including the ampullary part, after which a contraction of the smooth muscles of the seminal vesicles and prostate gland occurs, powerful contractions of the striated muscles of the ischiocavernosus and cavernous-bulbous muscles are added , muscles of the pelvic floor and perineum, as a result of which the ejaculate is thrown out with considerable force. Regulation of the act of ejaculation is carried out by the sympathetic and parasympathetic departments nervous system and under the influence of spinal cord impulses.

Male urethra (urethra masculina) It is a narrow tube 22-25 cm long, consisting of mucous and muscular membranes, which serves to remove urine and semen. The urethra takes on the shape of the canal only during the act of urination or ejection of sperm, and at rest the longitudinal folds of the mucous membrane are directly adjacent to one another. The urethra begins at the base of the bladder with the internal opening (ostium urethrae internum) and ends at the tip of the penis with the external opening (ostium urethrae externum). Anatomically, it is divided into the prostatic part (pars prostatica), membranous (pars membranacea) and cavernous (pars cavernosa). From the latter, there is also a bulbous part (pars spongiosa), corresponding to the bulbus urethrae, and a part enclosed in the head of the penis. From a clinical point of view, the entire urethra is usually divided into two sections: anterior and posterior. By anterior we mean the cavernous part of the canal, and by posterior we mean all its other parts up to the internal opening.

Along its path, the urethra forms two bends: the upper subpubic bend, at the transition of the membranous part of the urethra into the cavernous part, is concavely directed upward and anteriorly, the lower prepubic bend, at the transition of the fixed part of the urethra into the mobile one, is concavely directed downward and posteriorly. If the penis is raised to the anterior abdominal wall, then both curves transform into a common curve, concavely facing forward and upward. Throughout its entire length, the urethra has an unequal lumen diameter: narrow parts alternate with wider ones. One narrowing is located at its internal opening, another - when the urethra passes through the urogenital diaphragm, the third - at the external opening of the urethra. There are also three dilations: in the prostatic part, in the bulbous part and at the end of the urethra, where the navicular fossa (fossa navicularis) is located. On average, the width of the urethra is 4-7 mm.

Prostatic urethra located vertically between the internal and external sphincters of the bladder. Throughout its entire length it penetrates the prostate gland. Its length is 3-4 cm. The internal opening of the urethra is covered by ring-shaped muscles. The crest of the urethra (crista urethralis) is located on the posterior wall of the prostatic urethra. In its center there is an elevation - the seminal tubercle (colliculus seminalis), at the top of which there is a blind depression - the rudimentary male uterus (utriculus prostaticus). On the sides of it are the mouths of the ejaculatory ducts (ductus ejaculatorii) and the ducts of the prostate gland (ductuli prostatici).

Membranous part of the urethra(see Fig. 1) starts from the end of the prostatic part and extends to the place where the urethra enters the corpus cavernosum. This is the shortest and narrowest part of the urethra, its length is 1.5-2.5 cm. Adjacent to the posterior wall of the membranous part of the urethra are the Cooper glands (glandulae bulbourethrales), the excretory ducts of which open in the cavernous part of the urethra. The membranous part of the urethra is surrounded by m. sphincter urethrae membranaceus, associated with m. prostaticus.

Cavernous part of the urethra is the longest - it starts from the urogenital diaphragm and extends to its external opening. Its length is 12-15 cm. At the tendon center of the perineum, its end is flask-shaped (bulbus penis). In the posterior part of the cavernous part of the urethra, the excretory ducts of the Cooper glands open. In the anterior part, in the region of the head, there is a navicular fossa (fossa navicularis). On its anterior wall there is a fold of the mucous membrane - the valve of the navicular fossa (valvula fossae navicularis).

On the mucous membrane of the urethra there are depressions - the pits of the urethra (lacunae urethrales) and glands (glandulae urethrales). The muscular layer of the urethra consists of smooth and striated muscles.

The urethra is fed by small twigs from a. pudenda interna, which, anastomosing among themselves, form an arterial network around the urethra, mainly in the submucosal layer. In addition, the prostatic part of the urethra receives blood from a. rectalis media and a. vesicalis inferior, membranous - from a. rectalis inferior and a. perinealis, bulbous - from a. bulbi penis, cavernous - from a. urethralis. A. dorsalis penis and a. profunda penis also supplies the wall of the urethra with its branches (V.N. Tonkov). The veins of the urethra form plexuses from which blood flows into the v. dorsalis penis to v. profunda and into the veins of the bladder.

Lymph from the cavernous and membranous parts of the urethra flows into the nodi lymphatici inguinalis, and from the prostatic part into the lymphatic vessels of the prostate gland.

Innervation the urethra is carried out by nn. perineales and n. dorsalis penis, partly from plexus prostaticus (V.N. Tonkov).

Female urethra (urethra feminma) morphologically corresponds to the pelvic part of the male urethra. The length of the canal is 2.5-4 cm. It begins at the neck of the bladder, i.e., from the internal vesical opening, and ends with the external opening at the entrance to the vestibule of the vagina under the clitoris. The female urethra is supplied with blood through the a. pudendae internae and a. vaginalis. Venous blood enters the Santo Rinia plexus. Lymph flows into the external iliac nodes. The nerves of the female urethra come from the plexus hypogastricus inferior, s. plexus pelvinus (A.P. Tsulukidze).

The urethra is the tube through which urine is released from the bladder. The course of such a tube begins from the bladder, or rather, from its bottom. It consists of muscles, outside the act of urination it is in a collapsed state, i.e. one wall is adjacent to the other. The walls of the urethra can stretch up to 7-8 cm. The structure of the male and female urinary canals has fundamental differences.

Features of the structure of the male urethra

The urethra in men, moving away from the bladder, passes through the head of the prostate, through the pelvic fascia and goes through the shaft of the penis. At the head of the penis, the urethra ends with an opening. The mouth has the shape of a slit and is located vertically. The average size of the urethra is 17 cm. The male urethra has a configuration in the shape of the letter S. It is divided, from a physiological point of view:

  • urinary canal;
  • urogenital canal.

Surgeons have the following division of the urethra:

  • posterior section;
  • middle section;
  • anterior section

It distinguishes several anatomical curves, as well as three parts:

  • prostate part;
  • membranous part;
  • spongy part.

But some authors also distinguish the intramural part. The channel for excreting urine begins with the intramural part. It is surrounded by muscles, partly connected to the prostate, partly to the bladder. The muscles are called the internal urethral sphincter. The neck of the bladder and the beginning of the urethra are located 4 cm from the posterior surface of the pubic symphysis. According to studies, the intramural part is capable of changing size depending on the fullness of the bladder.

Prostatic part located as close as possible to the bladder, it is the widest and most distensible part of the urethra. Its length is about two and a half centimeters. Smooth muscles are located around the circumference of this section; they strengthen the sphincter of the bladder. In relation to the urethra, the prostate, in most cases, lies mostly behind. In the initial and terminal parts, the lumen of the prostate is narrow. In the middle third of the prostate, the seminal mound is located along the posterior wall, around which the efferent openings of the prostate ducts open. The urogenital diaphragm extends below the prostate. Behind it begins the membranous urethra. Surrounded by two muscle layers. The membranous part is the smallest, its length is one centimeter. It stretches from the prostate to the penis. The bulbourethral glands lie on the outer surface behind. The membranous section is well fixed by the urogenital diaphragm, which is why this section is inactive. It contains the external urethral sphincter.

The spongy part is located over a length of 15 cm. The spongy part is divided into a movable section and a fixed section. The transition from one to the other is located at the location of the ligament that supports the penis. This section is surrounded by the spongy substance of the penis. The course of the spongy section in the penis is slightly slanted; there is an area in the urethra that is not covered with spongy substance; it is the most vulnerable.

In addition to the anatomical division, in urology, according to the course of inflammation in the urethra, the anterior and posterior parts are distinguished. The line between them is the urethral sphincter. It prevents the infection from spreading from the anterior to the posterior urethra.

At at different ages men vary the size of the urethra; in boys it is narrower and shorter. The bend in the back is more pronounced.

Female urethra

The urethra in women has a number of features. The beginning of the canal is located in the neck of the bladder. Further, the course of the urethra will be parallel to the course of the vagina, the urethra ends in the vestibule of the vagina between the clitoris and the entrance of the vagina. The size of the urethral opening is about half a centimeter and has a round shape. A woman's urethra is completely immobile, unlike a man's. It is also wider and shorter. The posterior wall is fused to the vagina, the anterior wall is located next to the pubic symphysis. There is a narrowing in the area of ​​the outer and inner holes. The Skene's gland is located along the wall of the urethra, which is located behind. They secrete a secretion that is similar to the secretion of the prostate. But its function is not fully understood.


In both men and women, the urethra consists of three layers: submucosal, muscular and mucosal

Blood supply

The blood supply to the urethra is very complex. Its different parts feed different vessels. The arterial network of the urethra arises from the internal iliac artery. The prostatic part is fed from the middle branch of the rectal artery and the inferior artery of the bladder, the arteries of the urethra are formed from the branches of the internal iliac artery, the membranous part is from the lower branch of the rectal artery and the perineal artery, and the spongy part is fed from the internal pudendal artery. Venous drainage goes to the veins of the penis and bladder.

Functions performed

The urethra in women and men also differs in the functions it performs. In men, it performs three functions:

  • keeps urine in its reservoir;
  • takes her out;
  • conducts sperm during sex, or more precisely, at the moment of orgasm.

Urinary retention is accomplished through the work of two sphincters, namely: located inside and outside. If the bladder is poorly filled, then the sphincter located inside holds the urine, and when the bladder is full, the sphincter located outside.

The excretion of urine occurs when the bladder is full, then the urge to deurinate is formed, the muscles become relaxed by an effort of will, and under the influence of the muscular corset of the abdominal press and the bladder, urine is excreted.

The release of ejaculate occurs as follows. The sphincter inside is contracted, the prostate muscles are also contracted, the seminal hill swells. The corpora cavernosa swell and pull back the canal walls. The seminal mounds contract intermittently, expelling fluid. Also, the expulsion of ejaculate is facilitated by the contraction of the muscle layer of the ejaculatory duct and prostate, but the bulbospongiosus muscle still plays the main role in ejaculation.

In the fair half, the urethra has two functions:

  • urine retention;
  • her conclusion.

Pathology of the urethra

Pathological changes in the urethra can be divided into congenital and acquired. Among congenital ones there are:

  • lack of channel;
  • doubling;
  • diverticulosis;
  • hypospadias is a splitting of the wall of the posterior urethra, most often observed in males;
  • epispadias – incomplete fusion of the anterior wall of the urethral canal;
  • infravesicular obstruction is a disturbance in the flow of urine in the area of ​​the bladder neck or urethra. This may be due to congenital stricture of the cervix, valvular formations of the canal, large sizes of the seminal tubercle, complete fusion of the urinary canal.

The clinical picture of congenital urethral pathology is generally similar, regardless of its type (the exceptions are hypospadias and epispadias). The normal act of urination is disrupted, urinary incontinence or complete retention occurs, and the bladder overflows. The more narrowed the urethra, the sooner the clinic will manifest itself. In children, the abdominal press tenses during the act of urination. The stream of urine is sluggish, uneven, and the child urinates for a very long time. The bladder increases in size, urethritis, cystitis, and pyelonephritis often occur. The outcome may be chronic renal failure.

Epispadia manifests itself as discomfort when urinating, curvature of the penis; epispadia occurs very rarely in girls. With hypospadias, the urethra opens behind the head along the posterior surface of the penis with an opening in the form of a slit, and with the scrotal form - along the midline of the scrotum. There is a frequent urge to urinate, and the act itself is accompanied by difficulty.


Schematic illustration of various urethral malformations

Among the acquired pathologies of the urethra, stricture is distinguished, but it is worth noting that it can also be congenital. As a rule, stricture develops in men, which is associated with the structural features of their genitourinary system.

Acquired pathology

Urethritis is an inflammatory process in the urethra. It can develop in both men and women. But it still occurs more often in women, which is associated with easy penetration of infection into the urethra (it is wider and shorter than in men). Urethritis can be caused by viruses, bacteria, or chemicals. It manifests itself as a burning sensation, pain when urinating, and the release of blood and mucus.

In addition, among acquired pathologies it is worth noting cancer and benign neoplasms. Common symptoms include difficulty and pain when urinating, urinary retention, frequent urge to urinate, and pain during sexual intercourse. The intensity of symptoms directly depends on the size of the tumor.

Skinitis is an inflammation of the paraurethral glands or Skene glands in women. Reveals itself this pathology burning, pain during and after sexual intercourse, difficulty urinating.

Also among acquired pathologies, trauma to the urethra is distinguished. They are closed and open. Injuries without breaking the integrity of the skin are considered closed. The main cause of injury is fracture of the pelvic bones. In addition, medical manipulation may be an etiological factor. In women, trauma to the urethra sometimes occurs during childbirth.

Disruption of the normal functioning of the urethra in women occurs when carrying a child, after childbirth. They have urinary incontinence and dysuric phenomena. In addition, older women also have problems with the urethra.

In men, dysuria is mainly due to the fact that with benign prostate dysplasia or with oncology of this organ, the formation compresses the urethra, disrupting the normal flow of urine.

Conclusion

It is very difficult to analyze the anatomy of the urethra in detail for a person who does not have a medical education. However, everyone should know the basics of structure. Knowing your body makes it possible to treat it more carefully and carefully, preventing various diseases. Stay healthy.



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