ANATOMY

Detailed explanation-1: -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.

Detailed explanation-2: -The trigone is formed predominantly from bladder muscle. Histological studies suggest that two muscle groups reside in the trigonal region: the detrusor muscle of the bladder and longitudinal ureteral fibers.

Detailed explanation-3: -The fundus is the base of the bladder, which is formed by the posterior wall and contains the trigone of the bladder, and is lymphatically drained by the external iliac lymph nodes.

Detailed explanation-4: -Adrenergic receptors (predominantly 1) are concentrated in the trigone, bladder neck, and urethra. Norepinephrine-containing nerve cells are distributed in the paravesical and intramural ganglia, which maintain continence by producing contraction of the bladder neck and urethral smooth muscle.

Detailed explanation-5: -Sensations of bladder fullness are conveyed to the spinal cord by the pelvic and hypogastric nerves1, 8, whereas sensory input from the bladder neck and the urethra is carried in the pudendal and hypogastric nerves. The afferent components of these nerves consist of myelinated (A) and unmyelinated (C) axons.