This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
The commonest site of Branchial cysts is - 
Select and explain. 
A. Upper 1/3rd of the SCM, B. Lower 1/3rd of the SCM, C. Upper 2/3rd of the SCM, D. Lower 2/3rd of the SCM
A: Upper 1/3rd of the SCM
Answer: A: Upper 1/3rd of the SCM 
Explanation: Branchial cysts are characteristically found anterior and deep to the upper third of the sternocleidomastoid muscle. Branchial fistulas (those derived from 2nd branchial cleft) open externally in the lower third of necic, near the anterior border of sternocleidomastoid. Its internal orifice is located in the tonsillar fossa.
Branchial cysts & fistulas 

are remnants of the branchial apparatus present in fetal life.
branchial cysts, fistulas or sinuses are lined by squamous epithelium.