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| | The Ureters |
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| [[Anatomy]] > [[Gray's Anatomy| Gray's Anatomy of the Human Body]] > XI. Splanchnology > 3b. 2. The Ureters
| | The ureters are muscular tubes that transport urine from the kidneys to the urinary bladder. Each human has two ureters, one attached to each kidney. They play a crucial role in the urinary system by facilitating the passage of urine. |
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| [[Henry Gray]] (1821–1865). Anatomy of the Human Body. 1918.
| | ==Anatomy== |
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| == '''The Ureters''' ==
| | The ureters are approximately 25 to 30 centimeters long and have a diameter of about 3 to 4 millimeters. They are retroperitoneal structures, meaning they are located behind the peritoneum, the lining of the abdominal cavity. |
| The '''ureters''' are the two tubes which convey the urine from the [[kidneys]] to the [[urinary bladder]]. Each commences within the [[sinus]] of the corresponding kidney as a number of short cup-shaped tubes, termed '''[[calyces]]''' which encircle the renal [[papillae]]. Since a single [[calyx]] may enclose more than one papilla the calyces are generally fewer in number than the pyramids—the former varying from seven to thirteen, the latter from eight to eighteen.
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| The calyces join to form two or three short tubes, and these unite to form a funnel-shaped [[dilatation]], wide above and narrow below, named the '''[[renal pelvis]]''' which is situated partly inside and partly outside the renal sinus. It is usually placed on a level with the [[spinous process]] of the first [[lumbar vertebra]].
| | ===Structure=== |
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| === The '''Ureter Proper''' ===
| | The ureters are composed of three layers: |
| The '''Ureter Proper''' measures from 25 to 30 cm. in length, and is a thick-walled narrow cylindrical tube which is directly continuous near the lower end of the kidney with the tapering extremity of the [[renal pelvis]]. It runs downward and medialward in front of the [[Psoas major]] and, entering the [[pelvic cavity]], finally opens into the [[fundus]] of the bladder.
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| === The '''abdominal part''' ===
| | * '''Mucosa''': The innermost layer, lined with transitional epithelium, which allows for expansion and contraction. |
| The '''abdominal part''' (''pars abdominalis'') lies behind the [[peritoneum]] on the medial part of the [[Psoas major]], and is crossed obliquely by the internal [[spermatic vessels]]. It enters the pelvic cavity by crossing either the termination of the common, or the commencement of the external, [[iliac vessels]].
| | * '''Muscularis''': The middle layer, consisting of smooth muscle fibers arranged in circular and longitudinal layers, which facilitate peristalsis. |
| | * '''Adventitia''': The outermost layer, composed of connective tissue that provides support and protection. |
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| | ===Course=== |
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| At its origin the ''right'' ureter is usually covered by the descending part of the [[duodenum]], and in its course downward lies to the right of the [[inferior vena cava]], and is crossed by the right colic and [[ileocolic vessels]], while near the superior aperture of the [[pelvis]] it passes behind the lower part of the mesentery and the terminal part of the [[ileum]].
| | The ureters originate from the renal pelvis of each kidney and descend along the posterior abdominal wall. They cross the pelvic brim and enter the bladder at the ureterovesical junction. |
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| The ''left'' ureter is crossed by the left colic vessels, and near the superior [[aperture]] of the [[pelvis]] passes behind the [[sigmoid colon]] and its mesentery. | |
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| === The '''pelvic part''' ===
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| The '''pelvic part''' (''pars pelvina'') runs at first downward on the lateral wall of the pelvic cavity, along the anterior border of the greater [[sciatic[[ notch and under cover of the [[peritoneum]]. It lies in front of the [[hypogastric artery]] medial to the [[obturator nerve]] and the [[umbilical]], obturator, inferior [[vesical]], and middle [[hemorrhoidal arteries]].
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| Opposite the lower part of the greater [[sciatic foramen]] it inclines medialward, and reaches the lateral angle of the bladder, where it is situated in front of the upper end of the seminal vesicle and at a distance of about 5 cm. from the opposite ureter; here the ductus deferens crosses to its medial side, and the vesical veins surround it. Finally, the ureters run obliquely for about 2 cm. through the wall of the bladder and open by slit-like apertures into the cavity of the [[viscus]] at the lateral angles of the [[trigone]]. When the bladder is distended the openings of the ureters are about 5 cm. apart, but when it is empty and contracted the distance between them is diminished by one-half. Owing to their oblique course through the coats of the bladder, the upper and lower walls of the terminal portions of the ureters become closely applied to each other when the viscus is distended, and, acting as valves, prevent [[regurgitation]] of urine from the bladder.
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| <center>http://www.wikimd.org/images/gray/large/image1134.gif </center>
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| FIG. 1134– Transverse section of ureter. (''Picture From the Classic Gray's Anatomy'')
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| In the '''[[female]]''' the ureter forms, as it lies in relation to the wall of the [[pelvis]], the posterior boundary of a shallow depression named the '''[[ovarian fossa]]''' in which the ovary is situated. It then runs medialward and forward on the lateral aspect of the [[cervix]] uteri and upper part of the vagina to reach the [[fundus]] of the bladder. In this part of its course it is accompanied for about 2.5 cm. by the [[uterine artery]], which then crosses in front of the ureter and ascends between the two layers of the broad ligament. The ureter is distant about 2 cm. from the side of the cervix of the [[uterus]]. The ureter is sometimes duplicated on one or both sides, and the two tubes may remain distinct as far as the fundus of the bladder. On rare occasions they open separately into the bladder cavity.
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| | ==Function== |
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| === '''Structure (Fig. 1134)''' ===
| | The primary function of the ureters is to transport urine from the kidneys to the bladder. This is achieved through peristaltic contractions of the muscularis layer, which propel urine downward. |
| The ureter is composed of three coats: '''[[fibrous]], [[muscular]]''' and '''[[mucous]] coats'''
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| | ==Clinical Significance== |
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| The '''fibrous coat''' (''tunica adventitia'') is continuous at one end with the fibrous tunic of the kidney on the floor of the [[sinus]]; while at the other it is lost in the fibrous structure of the bladder.
| | ===Ureteral Obstruction=== |
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| | Ureteral obstruction can occur due to kidney stones, tumors, or strictures. This can lead to hydronephrosis, a condition characterized by swelling of the kidney due to urine buildup. |
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| In the renal pelvis the '''muscular coat''' (''tunica muscularis'') consists of two layers, longitudinal and circular: the longitudinal fibers become lost upon the sides of the [[papillae]] at the extremities of the [[calyces]]; the circular fibers may be traced surrounding the [[medullary]] substance in the same situation. In the ureter proper the muscular fibers are very distinct, and are arranged in three layers: an external longitudinal, a middle circular, and an internal, less distinct than the other two, but having a general longitudinal direction. According to Kölliker this internal layer is found only in the neighborhood of the bladder.
| | ===Ureteral Reflux=== |
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| | Vesicoureteral reflux is a condition where urine flows backward from the bladder into the ureters, increasing the risk of urinary tract infections. |
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| The '''mucous coat''' (''tunica mucosa'') is smooth, and presents a few longitudinal folds which become effaced by [[distension]]. It is continuous with the mucous membrane of the bladder below, while it is prolonged over the [[papillae]] of the kidney above. Its [[epithelium]] is of a transitional character, and resembles that found in the bladder (see Fig. 1141). It consists of several layers of cells, of which the innermost—that is to say, the cells in contact with the urine—are somewhat flattened, with concavities on their deep surfaces into which the rounded ends of the cells of the second layer fit. These, the intermediate cells, more or less resemble columnar epithelium, and are pear-shaped, with rounded internal extremities which fit into the concavities of the cells of the first layer, and narrow external extremities which are wedged in between the cells of the third layer. The external or third layer consists of conical or oval cells varying in number in different parts, and presenting processes which extend down into the basement membrane. Beneath the epithelium, and separating it from the muscular coats, is a dense layer of fibrous tissue containing many elastic fibers.
| | ===Ureteral Injury=== |
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| | Injuries to the ureters can occur during surgical procedures or due to trauma. Prompt diagnosis and treatment are essential to prevent complications. |
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| === '''Vessels and Nerves''' === | | ==See Also== |
| The '''[[arteries]]''' supplying the ureter are branches from the [[renal]], internal [[spermatic]], [[hypogastric]], and inferior [[vesical]].
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| The '''[[nerves]]''' are derived from the inferior [[mesenteric]], spermatic, and [[pelvic plexuses]].
| | * [[Kidney]] |
| | * [[Urinary bladder]] |
| | * [[Urinary system]] |
| | * [[Peristalsis]] |
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| | ==External Links== |
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| === '''Variations''' ===
| | * [Ureter - Wikipedia](https://en.wikipedia.org/wiki/Ureter) |
| The upper portion of the ureter is sometimes double; more rarely it is double the greater part of its extent, or even completely so. In such cases there are two openings into the bladder. [[Asymmetry]] in these variations is common.
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| ==Function==
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| The ureters are a component of the [[urinary system]]. [[Urine]], produced by the kidneys, travels along the ureters to the bladder. It does this through regular contractions called [[peristalsis]].<ref name=Grays2016 />
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| <gallery>
| | {{Urinary system}} |
| File:Ultrasound_demonstration_of_ureteral_jet_effect_0301105703_1105300.gif|[[Medical ultrasound|Ultrasound]] showing a jet of urine entering the bladder (large black section) through the ureter.
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| </gallery>
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| ==References==
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| {{Reflist}} | |
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| {{Human systems and organs}}
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| {{Urinary system anatomy}}
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| {{Authority control}}
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| [[Category:Abdomen]]
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| [[Category:Urinary system]] | | [[Category:Urinary system]] |
| [[Category:Kidney]] | | [[Category:Anatomy]] |
| | | [[Category:Urology]] |
| {{grays}}
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The Ureters
The ureters are muscular tubes that transport urine from the kidneys to the urinary bladder. Each human has two ureters, one attached to each kidney. They play a crucial role in the urinary system by facilitating the passage of urine.
Anatomy
The ureters are approximately 25 to 30 centimeters long and have a diameter of about 3 to 4 millimeters. They are retroperitoneal structures, meaning they are located behind the peritoneum, the lining of the abdominal cavity.
Structure
The ureters are composed of three layers:
- Mucosa: The innermost layer, lined with transitional epithelium, which allows for expansion and contraction.
- Muscularis: The middle layer, consisting of smooth muscle fibers arranged in circular and longitudinal layers, which facilitate peristalsis.
- Adventitia: The outermost layer, composed of connective tissue that provides support and protection.
Course
The ureters originate from the renal pelvis of each kidney and descend along the posterior abdominal wall. They cross the pelvic brim and enter the bladder at the ureterovesical junction.
Function
The primary function of the ureters is to transport urine from the kidneys to the bladder. This is achieved through peristaltic contractions of the muscularis layer, which propel urine downward.
Clinical Significance
Ureteral Obstruction
Ureteral obstruction can occur due to kidney stones, tumors, or strictures. This can lead to hydronephrosis, a condition characterized by swelling of the kidney due to urine buildup.
Ureteral Reflux
Vesicoureteral reflux is a condition where urine flows backward from the bladder into the ureters, increasing the risk of urinary tract infections.
Ureteral Injury
Injuries to the ureters can occur during surgical procedures or due to trauma. Prompt diagnosis and treatment are essential to prevent complications.
See Also
External Links
