Final answer:
False, during exhalation the spine does not move into flexion; the diaphragm relaxes and moves up, increasing air pressure in the lungs to expel air.
Step-by-step explanation:
False. During exhalation, the spine does not move into flexion. Rather, exhalation is primarily a passive process that involves the diaphragm relaxing and moving upward, which decreases the volume in the thoracic cavity and increases air pressure inside the lungs. As a consequence, air is expelled from the lungs.
Flexion of the spine is an anterior forward bending motion, which typically occurs as part of active movements such as bending the body forward. During normal breathing, the spine remains relatively stable and is not involved in the flexion or extension movement that characterizes active bending or straightening of the body.
Additionally, forced exhalation can involve the use of internal intercostal and abdominal muscles, but this is generally to aid in expelling air more forcefully and is not considered flexion of the spine. Extension in the context of the vertebral column refers to a posterior-directed motion.