This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
In urinary bladder, the smooth muscles is arranged in spirals bundles are known as: 
Select and explain. 
A. Detrusor muscle, B. Petrusser muscle, C. Brunners muscle, D. Nrest muscle
A: Detrusor muscle
Answer: A: Detrusor muscle 
Explanation: (Detrusor muscle) Ref: 357-Snell 7th, 435-BDC-2* The urinary bladder is a muscular reservoir of urine, which lies in the anterior part of the pelvic cavity. The detrusor muscle of urinary bladder is arranged in whorls and spirals and is adapted for mass contraction rather than peristalsis: (345-BDC-2)* The muscular coat of the bladder is composed of smooth muscles and is arranged as three layers of interlacing bundles known as detrusor muscle, At the neck of the bladder, the circular component of the muscle coat is thickened to form the sphincter vesicae (375-Snell 7th)