<prompt> In congenital hyperophic pyloric stenosis, the defect is inNerve fibresCircular muscle fibresLongitudinal muscle fibresMucosa  <response>: Infantile Hyperophic Pyloric stenosis In HPS, hyperophy of circular muscle of pylorus results in constriction obstruction of gastric outlet Accquired condition Incidence of 1 in 3000 to 4000 live bihs This condition is most common between the ages of 3-6 weeks Associated anomalies in 6-20 cases : Esophageal atresia, Hirschprungs disease, ARM and malrotation Ref: Sabiston 20th edition Pgno : 1869 