<prompt> Which muscle is irritated by inflamed retrocaecal appendixPsoas majorGluteus maximusQuadratus femorisObturator internus  <response>: Answer- A. Psoas majorIn children with abdominal pain, who hold their right hip in a flexed position to obtain relief from the pain, one should suspect retrocaecal appendicitis causing irritation ofthe psoas muscle. 