This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
The collaural fistula is an abnormality of 
Select and explain. 
A. 1st branchial arch, B. 1st branchial cleft, C. 2nd branchial arch, D. 2nd branchial cleft
B: 1st branchial cleft
Answer: B: 1st branchial cleft 
Explanation: The collaural fistula is a 1st branchial cleft anomaly which arises from the failure of fusion of the ventral pa of the 1st cleftIts upper pa opens into the floor of the external auditory canalIts lower pa opens in the neck between the angle of the mandible and sternocleidomastoid muscleRef: PL Dhingra, Diseases of Ear, Nose & Throat, 7th edition, pg no. 53