The Urinary bladder

• In the adult, the bladder lies in the minor pelvis, posterior to the pubis.
  
  
• It is separated by the retropubic space with fat.
  
  
• In infants and children, the bladder is in the abdomen, beginning to enter the pelvis major at about 6yrs.
  
  
• It reaches the pelvis at puberty.
  
  
• The shape, size, positions and relations vary with the amount of urine it contains and with age.

Peritoneal relations

• The superior part is covered posteriorly, cranially and anteriorly
• vesico uterine pouch in the females and the recto vesical pouch in the male.

• Superior surface, facing upwards
• Two inferior lateral surfaces, facing inferiorly
• Posterior surface facing posteriorly and inferiorly. This is also called the base
• Where the base and infero lateral surfaces converge, is called the neck of bladder.
• This is where the lumen of the bladder opens into the urethra and rests on the prostate gland in the male.

• The entire organ is enveloped by vesical fascia, a layer of loose connective tissue in which there is the vesical venous plexus
  
  
• The neck is held firmly by pubo prostatic ligaments in males and the pubo vesical ligament in the female.
  
  
• Major support is derived from the pelvic and urogenital diaphragms.

• Superior vesical arteries from the umbilical artery
  
  
• Inferior vesical arteries from the internal iliac
  
  
• Small branches from obturator and inferior gluteal arteries
  
  
• In females, uterine and vaginal arteries give branches to the bladder.
  
  
• The veins correspond to  the arteries. From the vesical venous plexus  and are tributaries of the internal iliac vein.
  
  
• Note: The vesical venous plexus in males envelopes the base of the bladder and prostate. The seminal vesicles, ductus deferens and inferior ends of the ureters
  
  
• It is connected to the prostatic venous plexus
  
  
• It may drain via sacral veins into the vertebral venous plexus
  
  
• In females it envelopes the pelvic part of the urethra and the bladder neck. It receives blood from the dorsal vein of the clitoris.
  
  
• It communicates with the vaginal plexus

Lymphatics

• From the superior part – external iliac nodes
  
  
• From the inferior part- internal iliac nodes
  
  
• Some from the neck- sacral and / or common iliac nodes

Innervation

• Parasympathetic fibres from the pelvic splanchnic nerves are motor to the detrusor muscle and inhibitory to the internal sphincter of the bladder
  
  
• Sympathetic fibres are derived form T11- L2.
  
  
• These fibres are inhibitory to the bladder and excitatory to the internal sphincter muscles.
  
  
• The nerves form a vesical plexus consisting of both sympathetic and parasympathetic fibres. It is continuous with the inferior hypogastric plexus.
  
  
• The external sphincter with other perineal muscles is supplied by pudendal nerve.