Final answer:
General anesthesia is most commonly achieved via inhalation using an anesthesia machine or through intravenous injections. Volatile liquids or gases and various injectable drugs are used to induce and maintain unconsciousness during surgical procedures.
Step-by-step explanation:
The routes in which general anesthesia is most commonly achieved are through inhalation and injection. Inhalational anesthetics, either volatile liquids or gases, are delivered using an anesthesia machine which composes a mixture that includes oxygen and ambient air, in addition to the anesthetic. The machine also allows for the vaporization of liquid anesthetics before they are inhaled by the patient.
For the injection route, intravenous anesthetics are preferred due to their quick action and reliability. Drugs such as propofol, etomidate, barbiturates, benzodiazepines, and ketamine are administered intravenously to induce and maintain unconsciousness. The selection of anesthetic depends on various factors, including the nature of the surgery and the condition of the patient.