In the mid-2260s, Dr. Cortejo was assigned to the medical department on the USS Enterprise. Cortejo was not a popular officer on the ship, with an arrogant and imperious manner towards others, especially non-medical personnel. Doctor Leonard McCoy disliked Cortejo's style, but respected his medical skills.
Dr. Cortejo served as acting chief medical officer of the Enterprise for a period of about two weeks while Dr. McCoy was recovering from a head injury which had resulted in severe amnesia. (TOS novel: Dreams of the Raven)