Yawning, stretching and functions integration in living organisms

It seems that evolution of living creatures in general can’t be compared to the lost ship which chaotically driven by wild winds in the heart of ocean but rather its progress has reason, target and direction. It means that we can speak about laws that govern evolution and formed living creatures as we know them today. This understanding can result in better quality of our life and actually can be the basis for the practical methods that can significantly improve our well-being. These methods are described in other chapters and outlying natural ways for power development, improvement of stance, motion, martial arts and health.     

Development of the living organisms in evolution perspective, as we believe, serves them for taking an active role in conquest of new ecological niches, new areas of habitat. It includes improvement in ability to move actively in surrounding space or better locomotion.

In order to provide this improved ability the Mother Nature applied synchronized and mutually supporting updates of different bodily systems – body structure and its motion, breathing mechanism, blood vessels system, nerve system and more. The most evident functions of the most living creatures, and especially of highly developed ones, are motion and breathing. Actually, with only exception of the most primitive organisms like corrals or jellyfish, the breathing includes motion clearly distinguishable by observer. The motion of breathing of fish and amphibian doesn’t support the locomotion (locomotion is a motion of organism in space like walking, running or swimming). The cooperation between these two systems in this stage of evolution exists only in one direction – the breathing supplies oxygen which makes living and locomotion possible. The things started to change with appearance of reptiles and dramatically changed with mammals. If we speak about humans the motion of thoracic diaphragm or simply diaphragm supports our upright stance and actually the diaphragm is one the most important organs responsible for this. The motion of the diaphragm helps us not only to stand upright but also to arise, to extent our upper body like during intake of the air.

During the reflexive stretching act, also known as pandiculation, the diaphragm pushes the ribs up, causing extension of the chest and spine. The diaphragm therefore plays extremely important role in mammalian locomotion. I prefer to call reflexive stretching act the power-stretching and use this term in place of stretching.
The much less known fact is that the motion of the glottis and especially of the hyoid bone during the yawning assists us to extent or rise our head. The motion of yawning has its origin in the breathing motion of the fish, amphibians and partially of reptiles. This dynamic head extension is a crucial part of mammalian locomotion. The motion of the hyoid also happens during power-stretching.

Power-stretching and yawning actually are simultaneous stretching and contraction of the muscles participating in breathing motion and in motions, supported by breathing. These stretching and contraction have isometric or quasi-isometric (almost isometric, we call it quasimetric) nature.

It seems that long lasting problem of meaning of the yawning and power-stretching has therefore quite simple solution. The yawning is an exercising, a repetition of the action of the most ancient breathing mechanism of vertebrae. This is essentially isometric action.

The mammals have younger mechanism of diaphragm breathing, which was created on the basis of the ancient one, subdued it, adjusted it to its needs and made it its “servant”. During the power-stretching, even without yawning, the hyoid bone travels down and therefore mammalian breathing apparatus exercising includes also initiation of the ancient progenitor, even in its initial form with closed mouth. This action is very often accompanied by stretchings and contractions of all body parts including the limbs whereas the body performs simulation of the automatic, reflexive actions of breathing and locomotion.   

These stretchings and simultaneous contractions during the yawning and power-stretching reach the maximum of intensity when moving parts of the body change their character of the motion – from flexion to extension and vice versa. There are most strenuous and demanding parts of motion. Mostly these flexions and extensions are pulled to their utmost extend, which is quite justifiable physiologically.

The isometric character of the muscle contraction during yawning and power-stretching results in post isometric relaxation (PIR). The isometric contractions keep muscles strong, especially in the most critical parts of the movement path.  PIR revitalizes monotonously acting muscles and nerve system, re-coordinates and re-integrates their joint activity and preparing them to the future action. The need for this recovery and revitalization can arise before we go to sleep, when we wake up or simply during the day. It supports natural functions of breathing, locomotion and stance, integrates them into one functional unity. All of them are most important, crucial and intensively used body actions.

I have outlined here a process of progressive cooperation and integration of some of the most vital functions of the organisms during the evolution. This process is similar in general to the process of cooperation and integration of the motor control’s levels as was proposed by Prof. N.A. Bernstein in his brilliant works. This is not surprising.   

   

Appendixes:

 

The most ancient fish Hyoid apparatus.

The sources:

http://courses.washington.edu/fish311/FISH%20311%20files/010-Feeding%20II.pdf  :

In primitive actinopterygians, i.e., living sturgeons, paddlefishes, and gars, the lowering of the mandible or opening the mouth is entirely dependent on lowering the floor of the throat. These primitive forms have only one means by which they can open the mouth, a biomechanical coupling called the hyoid coupling. All of these various movements of the jaws and the mouth cavity are made possible by a complex series of interlocking bones, and tendons and muscles attached to them. The complexity is increased by the fact that there is often more than one way to accomplish essentially the same movement. So let’s look in some detail at how fishes open their mouths. 2. THE HYOID COUPLING OF PRIMITIVE ACTINOPTERYGIAN FISHES Lower jaw depression is initiated by contractions of body musculature, the epaxial musculature above and the hypaxial musculature below. Contraction of the epaxial musculature, which inserts on the rear of the cranium, causes the head to rotate upward relative to the body axis… (beginning of 2 par. – M.G.).

This mechanism is then an indirect way of opening the mouth. Any opening of the mouth is preceded by a downward and backward movement of the floor of the mouth. This results in an expansion of the oral cavity… (end of 2 par. – M.G.) :

 

 

The most ancient amphibian Hyoid apparatus.

The sources:

http://www.answers.com/Q/What_is_the_function_of_the_hyoid_apparatus_in_frogs :

The hyoid apparatus brings about oscillating movement of the floor or the buccal cavity during the process of breathing...

 

http://www.brown.edu/Departments/Engineering/Courses/En123/MuscleExp/Frog%20Respiration.htm

 

The ancient reptilian Hyoid apparatus.

The sources:

http://www.ehow.com/info_7852672_kind-respiratory-system-do-reptiles.html :

Snakes and lizards don’t have diaphragm muscles for lung ventilation: muscles used for locomotion are the same used for their respiratory systems. Contracting and flexing body muscles moves their ribs and fill their lungs. Most squamate reptiles must hold their breath when they engage in bursts of intense physical activity. Some lizards complement lung ventilation with buccal pumping. This involves using throat muscles to help fill their lungs.

Crocodilians use a diaphragm muscle for lung ventilation, but their respiratory system differs from mammals. They use a hepatic piston, a process involving muscular movement of the pelvis and liver rather than the rib cage. This organ movement allows the lungs to expand.

http://www.newworldencyclopedia.org/entry/Reptile