Consider how oppressed and sterile the ward has been described before mcmurphy arrives. then consider how mcmurphy is described. what does the juxtaposition of these two descriptions foreshadow?

The juxtaposition of free and rambunctious Murphy's character with the sterile and restrictive, orderly ward foreshadows the eventual clash which occurs between these two ideas. Murphy's rebellion will either lead to a full out revolt or into the destruction of his disruptive personality. The ward cannot tolerate an anomaly or mutation within its sterile system, much like the body cannot tolerate an intrusive entity like a virus, it must be eradicated, which is exactly what  eventually happens when Murphy is put through process of a lobotomy, resulting in no longer being a threat to the host entity, the ward.