<prompt> A 25 years old male patient presents to the outpatient department with a midline swelling in the neck. OE there is no movement of the swelling on swallowing, but the swelling moves on protrusion of the tongue. The likely origin of the swelling is1st 2nd branchial arch4th branchial pouch4th branchial archMidline endoderm of pharynx  <response>: Answer: d Midline endoderm of pharynxTHYROGLOSSAL CYSTArise from the midline endoderm of pharynxMost common site is the sub-hyoid regionMidline swelling except in the region of thyroid cartilage where it is pushed usually to the left sideCongenital but swelling presents at the age of 15-30 yrsThyroglossal fistula is always acquiredCyst can be moved sideways but not up and downMoves up with the protrusion of tongue; moves with deglutitionRarely papillary carcinoma may developSurgery - Sistrunk operation removal of the cyst track central part of hyoid bone portion of the tongue base up to the foramen cecum 