Ureter Anatomy

Ureter

Introduction

The ureters are a pair of narrow, thick-walled muscular tubes which convey urine from the kidneys to the urinary bladder.

           They lie deep to the peritoneum, closely applied to the posterior abdominal wall in the upper part, and to the lateral pelvic wall in the lower part.

DIMENSIONS

 Each ureter is about 25 cm (10 inches) long, of which the upper half (5 inches) lies in the abdomen, and the lower half (5 inches) in the pelvis. It measures about 3 mm in diameter, but it is slightly constricted at five places. 

Course

General course of the ureter in the pelvis

The ureter begins within the renal sinus as a funnel- shaped dilatation, called the renal pelvis. The pelvis issues from the hilus of the kidney, descends along its medial margin, or partly behind it. Gradually it narrows till the lower end of the kidney where it becomes the ureter proper. 

      The ureter passes downwards and slightly medially on the tips of transverse processes and the psoas major muscle, and enters the pelvis by crossing in front of the termination of the common iliac artery.

       In the lesser or true pelvis, the ureter at first runs downwards, and slightly backwards and laterally. following the anterior margin of the greater sciatic notch. Opposite the ischial spine, it turns forwards and medially to reach the base of the urinary bladder.

Normal Constrictions 

Constrictions in the course of ureter

The ureter is slightly constricted at five places. 

1 At the pelviureteric junction.

2 At the brim of the lesser pelvis.

3 Point of crossing of ureter by ductus 'deferens or broad ligament of uterus.

4 During its oblique passage through the bladder wall. 

5 At its opening in lateral angle of trigone. 

Relations

Renal Pelvis 

In the renal sinus, branches of renal vessels lie both in front and behind it.

Outside the Kidney

Anteriorly 

On the right side, there are the renal vessels and the second part of the duodenum.  On the left side, there are the renal vessels, the pancreas, the peritoneum and the jejunum.

Posteriorly 

Psoas major muscle. 

Abdominal part of ureter

Anteriorly

On the right side, the ureter is related to:

Anterior relations of the abdominal part of the right ureter

1 Third part of the duodenum

2 Peritoneum 

3 Right colic vessels 

4 lleocolic vessels 

5 Gonadal vessels 

6 Root of the mesentery 

7 Terminal part of the ileum .  

On the left side, the ureter is related to: 

Anterior relations of the abdominal part of the left ureter

1 Peritoneum 

2 Gonadal artery 

3 Left colic vessels 

4 Sigmoid colon 

5 Sigmoid mesocolon.

Posteriorly 

Relations of the ureter to the transverse processes of lumbar vertebrae and the ischial spine

The ureter lies on 

1 Psoas major 

2 Tips of transverse processes

3 Genitofemoral nerve.

Medially 

On the right side there is the inferior vena cava;  on the left side, there is the left gonadal vein, and still further medially, the inferior mesenteric vein.  

Pelvic Part of Ureter 

Relations of the pelvic part of the ureter

In its downward course the relations are as follows.

Posteriorly 

1 Internal iliac artery

2 Commencement of the anterior trunk of the internal iliac artery 

3 Internal iliac vein 

4 Lumbosacral trunk 

5 Sacroiliac joint.

Laterally

1 Fascia covering the obturator internus 

2 Superior vesical artery 

3 Obturator nerve 

4 Obturator artery 

5 Obturator vein 

6 Inferior vesical vein 

7 Middle rectal artery 

8 In the female, it forms the posterior boundary of the ovarian fossa.  

          In its downward and forward course, the relations of ureter are different in males and females.  

In Males 

Posterior view of the male urinary bladder showing the relations of the ureter to the vas deferens and the seminal vesical

1 Ductus deferens crosses the ureter superiorly from lateral to medial side.  

2 Seminal vesicle lies below and behind the ureter.

3 Vesical veins surround the terminal part of ureter.

In Females 

Anterior view of the uterus and vagina showing the relations of the ureter to the uterine artery, the cervix of the uterus, and the vagina

1 The ureter lies in the extraperitoneal connective tissue in the lower and medial part of the broad ligament of the uterus.  

2 Literine artery lies first above and in front of the ureter for a distance of about 2.5 cm and then crosses it superiorly from lateral to medial side.  

3 The ureter lies about 2 cm lateral to the supravaginal portion of the cervix.  It runs slightly above the lateral for six of the tugina.  

4 The terminal portion of the ureter lies anterior to the tugina.  

Intravosical Part 

The intravesical oblique course of the ureter has a valvular action, and prevents regurgitation of urine from the bladder to the ureter.  The ureteric openings lie about 5 cm apart in a distended bladder, and only 2.5 cm apart in an empty bladder.  

Blood supply 

The ureter is supplied by three sets of long arteries: 

1 The upper part receives branches from the renal artery.  It may also receive branches from the gonadal, or colic vessels.  

2 The middle part receives branches from the aorta.  It may also receive branches from the gonadal, or iliac vessels.  

3 The pelvic part is supplied by branches from the vesical, middle rectal, or uterine vessels.  The arteries to the ureter lie closely attached to peritoneum.  They divide into ascending and descending branches which first form a plexus on the surface of the ureter, and then supply it.  

        The upper and middle parts receive branches from medial side, while the pelvic part gets its arterial supply from lateral side.  

Nerve Supply 

The ureter is supplied by sympathetic from T10 to L1 segments and parasympathetic from S2 to S4 nerves.  They reach the ureter through the renal, aortic and hypogastric plexuses.  All the nerves appear to be sensory in function.  

HISTOLOGY

Histology of the ureter

Ureter is composed of: 

1 The innermost mucous membrane.  

2 Middle layer of well developed smooth muscle layer.  

3 Outer tunica adventitia.  

      The epithelial lining is of transitional epithelium.  Muscle coat in upper two - thirds has inner longitudinal and outer circular fibers.  The lower one - the third comprises an additional outer longitudinal layer.  Connective tissue forms the outer layer.