Wikipedia: An exoskeleton (from Greek έξω, éxō "outer" and σκελετός, skeletos "skeleton") is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton (endoskeleton) of, for example, a human. In usage, some of the larger kinds of exoskeletons are known as "shells".
So as a human we supposedly only have an Exoskeleton that serves to contain, support and protect several of our vital organs... as well as serving as an attachment structure for muscle as a mechanism for transmitting muscular forces.
In Kyusho we begin to realize that we have a Shell or Exoskeleton of sorts.
Our first layer of protection or exoskeleton is our awareness and perception. We can sense, feel, see and hear danger approaching... this is the work of our nervous system, brain and energetic fields emitted from and beyond them like antenna. This is realized with aura, senses, vision and that gut feel.
The second layer is the hair and skin. Hair is in part has a sensory function, whereas the slightest moment transmits sensory input to the nervous system. The skin is also a sensory monitor right after the hair has been in contact with, with both of these structures accounting for the immediate sense of the feeling of touch. Additionally we have the sense reception lay of the Dermis or skin and is from the network of nerve corpuscles within the fatty layers of the skin that also pick up on touch, temperature, pressure and/or vibration.
The third layer is the nerve system, these are the larger transmitting peripheral nerves we associate most with Kyusho, Physiology and Functionality. This is a protective structural system that covers the entire body like a suit. It also serves to transmit sensory input first to the brain to then relay action transmission to the muscles in a coordinated process to withdraw the body from external dangers... this protective suit is like an outer layer of protection or exoskeleton per say.
Going Further In
Now where people stop at scientific premise, we must break the barriers of old concepts and limitations. To enact Kyusho we must understand all the possible protections between us and our goals. This is not just in the Martial Applications, it is also in healing (as bodies have an automated protection system that repels sensory inputs as well in some) and all other areas of Kyusho.
All of these exoskeleton protections and structures must be overridden to enable the extraordinary Kyusho affects (in all areas), this is not a hit the dot (pressure point) mentality or type of process, this is a full understanding of the human.
We are here to help you better your Kyusho... through deeper understanding, explanation and real anatomy.