APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals.

Detailed explanation-2: -The internal urethral sphincter is made of a layer of smooth muscle that is surrounded by striated muscle. The external urethral sphincter is composed of striated muscle and is located distally and inferiorly to the bladder neck in women between the vaginal orifice and clitoris.

Detailed explanation-3: -So, the correct answer is ‘Smooth muscles’

Detailed explanation-4: -Four distinct smooth muscle sphincters are present in the GI tract: the lower esophageal sphincter (LES), the pyloric sphincter (PS), the ileocecal sphincter (ICS), and the internal anal sphincter (IAS).