<prompt> Commonest site of branchial cyst isUpper one third of SCMLower one third of SCMUpper two third of the SCMLower two third of the SCM  <response>: Branchial cysts are characteristically found anterior and deep to the upper third of the sternocleidomastoid muscle. Branchial fistulasthose 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. Ref : Bailey Love 25e p727 