Bladder

                                  Bladder

The urinary bladder is Muscular hollow organ, wich function as the reservior for the urine received from the kidney and to discharge it out periodically. 

Shape:

         The empty bladder resembles a four sided pyramid it has:

  . Four angles_apex, neck and two lateral angles 

   . Four surfaces

          - Base (Posterior surface) 

          - Two inferolateral surfaces

          - superior surface

Position: 

Empty bladder in the adult is situated within the true pelvis. When distended, it rises  up to the abdominal cavity and becomes a abdominopelvic organ. In the newborn, it is abdominal in position. 

Capacity:

300-600ml of urine in adult. 

 In gross anatomy, the bladder can be divided into a broad Fundus a body, an apex, and a neck.The apex is directed forward toward the upper part of the pubic Symphysis, and from there the median  Umblical ligament continues upward on the back of the anterior abdominal wall of the Umblicus.

Apex – located superiorly, pointing towards the pubic symphysis. It is connected to the umbilicus by the median umbilical ligament (a remnant of the urachus).

Body – main part of the bladder, located between the apex and the fundus

Fundus (or base) – located posteriorly. It is triangular-shaped, with the tip of the triangle pointing backwards.

Neck – formed by the convergence of the fundus and the two inferolateral surfaces. It is continuous with the urethra.

                                peritonium is carried by it from the apex on to the abdominal wall to form the middle umblical fold. The neck of the bladder is the area at the base of the trigone that surrounds the internal urethral Orifice that leads to the urethra.In males the neck of the urinary bladder is next to the prostate gland. 

              The bladder has three openings. The two ureters  enter the bladder at ureteric orifices, and the urethra enters at the trigone of the bladder. These ureteric openings have mucosal flaps in front of them that act as valves in preventing the backflow of urine into the ureters, known as vesicoureteral reflux. Between the two ureteric openings is a  raised area   of tissue called the interureteric crest. This makes the upper boundary of the trigone. The trigone is an area of smooth muscle  that forms the floor of the bladder above the urethra. 


Blodd , vein, lymph supply:

                  The bladder receives blood by the vesical arteries  and drained into a network of vesical veins.The superior vesical artery supplies blood to the upper part of the bladder. The lower part of the bladder is supplied by the inferior vesical artery, both of which are branches of the internal iliac arteries. In females, the uterine and vaginal arteries provide additional blood supply.Venous drainage begins in a network of small vessels on the lower lateral  surfaces of the bladder, which coalesce and travel with the lateral ligaments of the bladder into the internal iliac veins.. 

         The lymph drained from the bladder begins in a series of networks throughout the mucosal, muscular and serosal layers. These then form three sets of vessels: one set near the trigone draining the bottom of the bladder; one set draining the top of the bladder; and another set draining the outer undersurface of the bladder. The majority of these vessels drain into the external iliac lymph nodes.


Nerve supply:

Sympathetic – hypogastric nerve (T12 – L2). It causes relaxation of the detrusor muscle, promoting urine retention.

Parasympathetic – pelvic nerve (S2-S4). Increased signals from this nerve causes contraction of the detrusor muscle, stimulating micturition.

Somatic – pudendal nerve (S2-4). It innervates the external urethral sphincter, providing voluntary control over micturition.



                             Written by:

                                                 Mr. Siddique shaikh

Contact:

Sheikhsiddequebuldana@gmail.com




       

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