Commonly tested and things I get mixed up on:

Cervical Sinus

Small pit at the anterior border of his left sternocleidomastoid muscle, w/ mucus dripping intermittently from the opening. The pit extended to the tonsillar fossa as a branchial fistula.

• Second pharyngeal pouch and cervical sinus
• Branchial fistula results from failure of closure of both the second pharyngeal pouch and the cervical sinus

Painless swelling on the right side of the neck. Well-defined cystic mass at the angle of the mandible, just anterior to the sternocleidomastoid muscle.

• Lateral cervical cyst is caused by remnants of the cervical sins and would present anterior to the sternocleidomastoid

Thyroglossal duct

Soft anterior midline cervical mass. Protrusion of the tongue moves the mass upward.

• Thyroglossal duct cyst occur due to retention of a remnant of the thyroglossal duct along the path followed by the descending thyroid gland during development
• Foramen cecum of the tongue > descend midline > final position of the thyroid

Accessory thyroid tissue is normally situated along the toure of descent of the thyroglossal duct, either in the posterior tongue or along the midline of the neck. A cyst of the thyroglossal duct would be found in locations similar to where accessory thyroid tissue is found.