Bladder

The bladder (vesica urinaria) is an unpaired hollow organ that serves as a reservoir for urine, which is discharged from the bladder through the urethra.

The shape and size of the bladder changes as it is filled with urine. The filled bubble has a rounded shape: Bladder capacity in an adult to 250-500 ml.

In the bladder, an anteroposterior part that is facing the anterior abdominal wall and the apex of the bladder (apex vesicae) are isolated. From the top of the bladder to the navel there is a fibrous lobe - the median umbilical ligament (lig.umbilicale medianum) - the remainder of the embryonic urinary duct (urachus). Without a pronounced boundary, the tip of the bladder passes into the expanding part - the body of the bladder (corpus vesicae). Continuing back and forth, the body of the bladder passes into the bottom of the bubble (fundus vesicae). The lower part of the bladder is funnel-shaped and narrows into the urethra. This part was called the neck of the bladder (cervix vesicae).

[1], [2], [3], [4], [5], [6]

Bladder topography

The bladder is located in the cavity of the small pelvis behind the pubic symphysis. With its front surface, it faces the pubic symphysis, from which it is delimited by a layer of loose fiber lying in the retrograde space. When the urinary bladder is filled with urine, the tip of the bladder appears as an ideo pubic symphysis and comes into contact with the anterior abdominal wall. The posterior surface of the bladder in men is due to the rectum, seminal vesicles and ampullae of the ovary ducts, and the bottom to the prostate gland. In women, the posterior surface of the bladder touches the anterior wall of the cervix and vagina, and the bottom - with the urogenital diaphragm. The lateral surfaces of the bladder in men and women border on the muscle that lifts the anus. To the upper part of the bladder, the males of the small intestine are attached to men, and in women - the uterus. The filled bladder is located in relation to the peritoneum mesoperitoneally, empty, asleep - retroperitoneally.

The peritoneum covers the bladder from above, from the sides and from behind, and then in men it passes to the rectum (rectum-vesicular cavity), in women - to the uterus (vesicle-uterine cavity). The peritoneum covering the bladder is connected to its walls loose. The bladder is fixed to the walls of the small pelvis and connected to a number of lying organs with the help of fibrous strands. With the navel, the upper end of the bladder is connected by the median umbilical cord. The lower part of the bladder is attached to the walls of the small pelvis and adjacent organs by ligaments formed by compressed connective tissue bundles and fibers of the so-called pelvic fascia. In men, there is a pubic-ligament ligament (lig.puboprostaticum), while in women there is a fibrobladder ligament (lig.pubovesicale). In addition to the ligaments, the bladder is also strengthened by muscular tufts forming the pubic-vesicle muscle (m.pubovesicalis) and rectal-bladder muscle (m.rectovesicalis). The latter is found only in men. In both men and women, the bladder is fixed to a certain extent through the initial part of the urethra and the end sections of the ureters, as well as the prostate gland in men and the urogenital diaphragm in women.

[7], [8], [9], [10]

Structure of the bladder

The walls of the bladder (in men and women) consist of a mucous membrane, a submucosal base, a muscular membrane and adventitia, and in places covered with a peritoneum, there is a serous membrane. In the filled bladder, the walls are stretched, thin (2-3 mm). After emptying, the bubble shrinks in size, its wall is contracted by the muscle shell and reaches a thickness of 12-15 mm.

The mucosa (tunica mucosa) lays the bladder from the inside and forms wrinkles with the emptied bladder. When filling the bladder with urine, the folds of the mucous membrane completely spread out. Cells of epithelium (transitional) covering the mucous membrane, with an empty bladder, are rounded, when it is filled and stretched, the walls are flattened and thinned. Epithelial cells are connected to each other by tight contacts. In the thickness of its own plate of the mucous membrane there are alveolar-tubular glands, nerve fibers, vessels and lymphoid formations. The mucous membrane of pinkish color, mobile, easily assembles into folds, with the exception of a small area in the bottom of the bladder - a triangle of the bladder (trigonum vesicae), where it is tightly fused to the muscle shell. In the anterior part of the bottom of the bladder (at the apex of the triangle), there is an internal opening of the urethra on the mucosa, and in each corner of the triangle (at the ends of the posterior border) is the ureter opening (right and left, ostium ureteris, dextrum and sinistrum). Along the base (posterior border) of the bladder triangle is the intercellular fold (plica interureterica).

The submucosa (tela submucosa) is well developed in the wall of the bladder. Thanks to it, the mucous membrane can be folded. In the area of the triangle of the bladder the submucosa is absent. Outside of it in the wall of the bladder is the muscular membrane (tunica muscularis), consisting of three fuzzy layers separated by smooth muscle tissue. The outer and inner layers have a predominantly longitudinal direction, and the middle, the most developed, circular. In the area of the neck of the bladder and the internal opening of the urethra, the middle circular layer is most well expressed. At the beginning of the urethra, a bladder compressor (m.sphincter vesicae) is formed from this layer. With the contraction of the muscular membrane of the bladder and the simultaneous opening of the squeezer, the volume of the organ decreases and urine is expelled outside through the urethra. In connection with this function of the muscular membrane of the urinary bladder, it is called a muscle that pushes urine (m.detrusor vesicae).

Vessels and nerves of the bladder

Upper umbilical arteries - the branches of the right and left umbilical arteries - approach the apex and the body of the bladder. The lateral walls and the bottom of the bladder are blood supplyed by the branches of the lower colibustral arteries (branches of the internal iliac arteries).

Venous blood from the wall of the bladder flows into the venous plexus of the bladder, as well as through the urinozubic veins directly into the internal iliac veins. Lymphatic vessels of the bladder flow into the internal iliac lymph nodes. The bladder receives sympathetic innervation from the lower hypogastric plexus, parasympathetic - along the pelvic internal nerves and sensitive - from the sacral plexus (from the genital nerves).

X-ray anatomy of the bladder

The bladder when filled with its contrasting mass on the roentgenogram (in anteroposterior projection) has the shape of a disc with smooth contours. With a lateral projection on the roentgenogram, the bladder acquires the shape of an irregular triangle. For the study of the bladder, cystoscopy is also used (examination of the mucous membrane). This method allows you to determine the condition, color, relief of the mucous membrane, the holes of the ureters and the flow of urine into the bladder.

The bladder in the newborn is fusiform, in children of the first years of life - pear-shaped. During the second childhood (8-12 years), the bladder is ovoid, and in adolescents it has the shape characteristic of an adult. The capacity of the newborn's bladder is 50-80 cm ³, by 5 years - 180 ml of urine, and in children over 12 years of age it is 250 ml. In the newborn, the bottom of the bladder is not formed, the triangle of the bladder is located frontally and is part of the posterior wall of the bladder. Circular muscle layer in the wall of the bladder is poorly developed, the mucous membrane is well developed, the folds are expressed.

The topography of the bladder in a newborn is such that its apex reaches half the distance between the umbilicus and the pubic symphysis, so the bladder in girls at this age does not come into contact with the vagina, and in boys with the rectum. The anterior wall of the bladder is located outside the peritoneum, which covers only its posterior wall. At the age of 1-3 years, the bottom of the bladder is located at the upper end of the pubic symphysis. In adolescents, the bottom of the bladder is at the level of the middle, and in adolescence - at the lower end of the pubic symphysis. Later, the bottom of the bladder falls, depending on the state of the muscles of the urogenital diaphragm.