Movement of the fluid endolymph bends the hairs of the crista in specific
directions. These are responses to linear and/or angular kinetic gravitational
Carrying the information from the maculae and the cristae to the brain is the
vestibular nerve. Contained in the same fibrous sheath from the membranous
labyrinth to the brain are the vestibular and auditory nerves. (para 11-37)
The simplest and lowest level of control is the reflex arc. Producing wider
reactions to stimuli are segmental reflexes. A number of nuclei in the hindbrain
monitor and control visceral functions of the body, including respiration and
heartbeat. The facilitatory and inhibitory areas of the reticular formation monitor
and control general body functions, including sleep. The thalamus is a primary
relay for information going to and from the cerebrum and cerebellum. One of the
most important integrators of motor activity of the body is the cerebellum.
In humans, the highest level of control is in the cerebrum. Here, we can clearly
designate three levels of control.
The first level is concerned with visceral activities of the body, as related to
fight-or-flight, fear, and other emotions.
At the second level, activities of the body are standardized and repetitive in
nature. An example is the sequence of muscle actions involved in walking.
At the third level, brand new solutions can be created. This is the volitional
End of Lesson 11