answer c. Balance is maintained by the coordination( integration) of inputs from eyes (visual cues,) semicircular canals, saccule and proprioceptors
Work Step by Step
Balance is maintained by a combination of the activities of all these structures-- eyes, semicircular canals saccule and proprioceptors. The saccule and utricle contain receptors called maculae, that respond to changes in the pull of gravity when the head changes position. These receptors have their cell bodies in the vestibular ganglion These changes are reported via the vestibular branch of the acoustic nerve ( cranial nerve VIII). Sensory impulses go to the cerebellum and to vestibular nuclei of the brainstem, from which efferent messages are sent to muscles of head and neck to modify positions. Semicircular canals ( two vertical and one horizontal) are three bony structures in the bony labyrinth of the inner ear. A membranous tube runs through each canal( the semicircular duct) which has an expansion--the ampulla-- at one the end. In the ampulla is the sensory epithelium or crista ampullaris. . The sense receptors of the crista ( hair cells) respond to head rotations and angular acceleration of the head ( rate of change of a rotating body). Proprioceptors. These receptors are found in skeletal muscle spindles, ligaments, tendons, joints and in connective tissue wrappings of bones and muscles. They include muscle spindles , Golgi tendon organs, Pacinian and Ruffini's corpuscles. They monitor stretch and tension of muscles, and changes of positions in limbs , trunk, neck, and structures in the oral cavity.Sensory impulses from proprioceptors go to brain stem, cerebellum and cerebrum, and are coordinated with impulses from visual and vestibular sources. Motor output is responsible for the vestibulo-ocular reflex, control of eye movements, and adjustments of skeletal muscle movements that control posture.. Binocular stereoscopic vision enable humans to form three dimensional(3D) images. Vision receptors --rod (and cones) and 3D vision facilitate focusing on an objects; concurrently impulses to the vestibular nuclei of the brain stem and spinal motor cortex enable estimation of the body's position in space in relation to other objects in the environment.