THE URINARY BLADDER

THE URINARY BLADDER 1 د.عبدالرزاق السلمان

SURGICAL ANATOMY • It is lined by transitional epithelium covering the connective tissue lamina propria, which contains a rich plexus of vessels and lymphatics.
• When the detrusor muscle hypertrophies, the inner layer, covered by urothelium, stands out, resulting in the appearance of trabeculation.
• Over the trigone is a thin layer of smooth muscle to which the epithelium is closely adherent and which extends as a sheath around the lower ureters and into the proximal urethra.
• Around the male bladder neck is the smooth muscle internal sphincter innervated by adrenergic fibres, which prevents retrograde ejaculation.
• The distal urethral sphincter is a horseshoe-shaped mass of striated muscle that lies anterior and distal to the prostate, or in the proximal two-thirds of the female urethra. It is distinct from the pelvic floor and is supplied by S2–S4 fibres via the pudendal nerve and by somatic fibres passing through the inferior hypogastric plexus.
Arteries
The superior and inferior vesical arteries are derived from the anterior trunk of the internal iliac artery. Branches from the obturator and inferior gluteal arteries (and from the uterine and
vaginal arteries in females) also help to supply the bladder.
Veins
The veins form a plexus on the lateral and inferior surfaces of the bladder. In the male the prostatic plexus is continuous with the vesical plexus, which drains into the internal iliac vein. In the female similar large veins are continuous with the vaginal plexus.
Lymphatics
These accompany the veins and drain to nodes along the internal iliac vessels and then to the obturator and external iliac chains.Some lymphatics pass to nodes that are situated posteriorly to the internal iliac artery (hypogastric nodes).