Urethra

The urethra , the urethra, starts from the inner opening of the urethra of the bladder and is a tube for urinating out, while it has very significant sex differences.

Male urethra (male urethra), urethra masculina, has a complex anatomical structure and serves not only to excrete urine, but also to excrete the seed, being also part of the external male genital organs.

The female urethra (female urethra), urethra feminina, is constructed much simpler and serves to excrete urine, being a part only of the urinary system.

The female urethra is shorter, but wider than the men's urethra; Its length varies from 3 to 4 cm, width is one and a half times the width of the male. Starting from the bladder with the inner opening of the urethra, ostium urethrae internum, the urethra passes through the urogenital diaphragm and opens with the outer opening of the urethra, ostium urethrae externum, on the threshold of the vagina, in the depth of the genital gaps. The external opening is round, surrounded by hard, cylindrical edges. The canal runs parallel to the vagina, along its anterior wall, with which it fuses, in the direction from above and from behind downwards and forward under the pubic symphysis. The lumen of the canal is not the same throughout: it is funnel-shaped widened in the bladder and narrows at the outer orifice. The canal is surrounded by a connective tissue, which is the most dense in the lower part of the vagina.

The wall of the urethra is formed by the muscular, spongy and mucous membranes.

The muscular membrane , tunica muscularis, consists of an outer circular layer and an inner longitudinal layer of smooth muscles with an admixture of elastic fibers. In the area of ​​the urogenital diaphragm, the muscles of the latter form the sphincter (compressor) of the urethra, m. Sphincter (m. Compressor) urethrae.

Spongy shell , tunica spongiosa, comparatively thin, is located between the muscular and mucous membranes; Thanks to a large amount of elastic tissue and a well-developed vascular plexus resembles a spongy tissue.

The mucosa , tunica mucosa, is covered by a multilayered flat, and in some areas by a high prismatic epithelium, forms a series of longitudinally extending folds, so that on the incision the lumen of the canal has a stellate shape.

The largest and highest fold on the posterior wall of the urethra is the crest of the urethra, crista urethralis, which extends from the anterior angle of the urinary bladder triangle to the end of the canal. In the lower sections of the canal on the mucosa open the mouth of the paraurethral ducts, ductus paraurethrales, and glands of the urethra, glandulae urethrales.

You will be interested to read this:

• Urinary organs.
• The kidneys .
• The ureter .
• Bladder .

On the surface of the mucosa there are small indentations - lacunae of the urethra, lacunae urethrales. Near the external opening of the canal, on both sides of it, one common duct of small glands opens at this site.

Innervation : plexus hypogastricus, pudendus, lumbalis.

Blood supply: female urethra - a. Urethralis (from a. Pudenda interna) and a. Vesicalis inferior. Venous blood flows into the plexus venosus vesicalis inferior, and then to v. Iliaca interna. Lymphatic vessels carry lymph to the nodi lymphatici paravesicales and iliaci interni.