Corpsman
Marine Corpsmen are enlisted personnel who have received extensive training in triage and trauma first aid. They are capable of stabilizing casualties, administering medications and even performing basic surgical procedures.
Corpsmen serve in a wide variety of capacities and locations, including planetary facilities such as hospitals and clinics, aboard ships as the primary medical caregiver for Marines while underway, or with Marine Corps units as battlefield medics.
Shipborne detachments are often assigned a Starfleet medic. Larger detachments, such as those on starbases and planetary bases, can support an independent medical department and may use a combination of Marine, Starfleet and private medical personnel.
If based in a medical facility a Marine Corpsman reports to the facility's chain of command. While assigned to a detachment the Corpsman reports to his Squad Leader and Marine Commanding Officer for day to day operations and to the ship's Chief Medical Officer for training.