Medical Assistant
Medical Assistants were essentially Staff Assistants with built in access to Medbay (but not anything inside Medbay). Medbay tends to have so much traffic that it is not hard to walk in to begin with, so this is often not that big of a deal. Nominally, the job involved following around the Medical Doctor and helping him with triage, or working alongside a Roboticist or Geneticist while they do whatever it is they do. This made it a great job for a new player - simply ask someone if they could show you how to do their job, and they will often happily do so.
Nowadays, Medical Assistants can be found helping people to the best of their abilities in Medbay, or the Head of Personnel's Office, begging for proper access to medical equipment.
Crew Objectives
As a medical assistant, you could expect to see the following:
End the round in perfect health
Just have 100 health. The simplest way to do this was to pump yourself with medicine near the end of the round, and if you were heading to the escape shuttle, hop into one of the sleepers for good measure.
Ensure the Head Surgeon gets off the station alive
The Head Surgeon started in Medbay and just had to be pulled onto the escape shuttle.
Escape on the shuttle alive as a monkey.
Just like today, they basically had to ask the Geneticists to make them into a monkey.
Escape on the shuttle alive with a non-assistant ID registered to you.
Usually meant asking the Captain or Head of Personnel for a job transfer or getting one off someone who couldn't be revived. Worth noting IDs for the other assistant types, i.e. Technical Assistant and Staff Assistant, did NOT count as "non-assistant".
RIP
Sadly, on December 23, 2012, the shuttle containing this shift's technical and medical assistants crashed. Into the moon. Forever. The Staff Assistant job got the Medical Assistant's objectives in their stead.
Light at the End of the Tunnel
However, on September 24, 2021, due to ballooning server population, the job returned as a latejoin job, along with the Technical Assistant, Research Assistant, and Head Surgeon.