Final answer:
The maneuver in question, characterized by bearing down on a closed glottis to stimulate the vagal reflex and decrease heart rate, is called the Valsalva maneuver.
Step-by-step explanation:
When bearing down on a closed glottis, stimulating the vagal reflex, and dropping heart rate, this maneuver is called the Valsalva maneuver. This maneuver involves a voluntary contraction of the diaphragm and abdominal wall muscles with a closed glottis, leading to increased intra-abdominal pressure. It can be used to facilitate defecation and is sometimes utilized in medical diagnostics to assess heart function and autonomic nervous system responses. In contrast to the options listed, such as Carotid sinus massage, Muller's maneuver, or the Trendelenburg position, the Valsalva maneuver directly affects venous return and, subsequently, heart rate and cardiac output by stimulating the baroreceptor reflex