Final answer:
The question addresses the balance and tension mechanisms within the human vestibular system, particularly how the semicircular canals and the cochlea help in maintaining balance and posture. Gymnasts utilize these structures to maintain equilibrium, and muscle exertion in the neck helps to keep the head erect by counteracting the weight of the head, which is not directly over the support joint.
Step-by-step explanation:
The student's question pertains to the physiological mechanisms that help maintain balance and equilibrium in the human body. Specifically, the technique mentioned relates to the tension balance in the membranous structures of the head, likely referring to the vestibular system, which includes the semicircular canals and the cochlea. The hair cells within the cochlea are anchored to the membrane allowing them to be activated by the movement of the fluids, thus aiding in auditory processing and balance.
Gymnasts, such as the one mentioned in Figure 11.50.3, use their semicircular canals in conjunction with their cerebellum for balance while performing on equipment like the balance beam. These structures work together to help the athlete maintain stability and orientation.
The information provided about muscle exertion, in particular the muscles at the back of the neck, illustrates how the body maintains balance and posture by exerting forces to counteract the offset of the head's center of mass from its principal point of support at the atlanto-occipital joint.