(2) Across this space to the striated muscle fiber, the command message is
carried in the form of a special chemical acetylcholine (ACh). Once the message has
been transferred, the ACh is degraded to no longer function.
(3) Nerve gases and organic phosphate insecticides produce their effects by
interfering with the transmission or reception of messages across the synaptic cleft.
g. Axial Versus Appendicular Muscular Control. The musculature of the
body can be thought of in two categories: axial and appendicular.
(1) The axial musculature includes the skeletal muscles of the trunk and the
upper and lower girdle regions.
(2) The appendicular musculature includes the skeletal muscles of the upper
and lower limbs beyond the girdles.
(3) These two categories are important because they are controlled by the
nervous system in different ways. Also, they react quite differently to various
physiological and nervous situations.
(4) The muscles that operate the hands tend to be very specifically and
highly controlled by the nervous system.