The definition of endoskeleton has already been given, and as the cartoon post image demonstrates, creatures with an exoskeleton are characterized by an external skeleton while the soft tissue remains contained within. If the question were to be asked "are humans endo or exo?", the odds are that 99.9% would say ENDO. Therefore, am I suggesting that we are EXO? As with all biological organisms, humans are a mixture of both.
This is an intuitive question, but requires some extensive leaps into evolution and the process by which man moved from water to land...which I will save for another time. However, it should be understood that because of the realities of entropy, we are engineered in the most efficient manner...therefore there must be an architectural reason for the development of a "hybrid skeleton". I will follow with a more detailed explanation of what i refer to as a hybrid skeleton, but i wanted to convey a fundamental message beforehand: the realities of moving within a gravitational field have resulted in an efficient blend of compressional and tensional properties (biotensegral properties) that allow for some of the most fluid and precise movements on the planet.
The Hybrid skeleton is characterized by an exoskeletal "core" and an endoskeletal "periphery". The core is defined by the thorax, abdomen, and pelvis...while the periphery are the limbs (including the neck).
|Soft visceral core|
|Visceral core within thoracic cage and pelvic girdle|
|Tensional characteristics of the arms|
This last stement will be the key focus of the "true posture" post to follow.
Again, credit to Richard Paletta for formalizing the visceral core concept with the images within this post. Further credit goes to the works of Frederick Woods Jones who makes some rather startling comparisons between the human organism and our sea-dwelling creatures.
Stay tuned for what will hopefully be an insightful formalization of an interesting concept of posture...more importantly how it fits onto the complex and comprehensive world of movement disorders.