The Impact of the Stomatognathic System on the Development of Human Beings

PRACTICE MINIREVIEW 171 The impact of the stomatognathic system on the development of human beings Question tion. Food was devoured without ism is linked to the brain, or CNS, in Which of the versatile complex func- chewing. A large part of the energy the most complex and versatile way. tions of the stomatognathic system contained in food was therefore The brain stem is largely in charge of play a key role in human devel- needed in processing the food in the neuronal control of “simple” func- opment? intestinal tract. Multidimensional tions such as chewing, defending or chewing, grinding of the food and threatening others. Among others, a Background predigesting through the addition of central area referred to as a mastica- The stomatognathic system and its saliva’s enzymes occurred more and tory center is located here. It controls comprehensiveness and meaning for more in the course of evolution. the chewing process after initiation the entire organism is underesti- Chewing movements became in- by associated centers in the cerebral mated even by dentists. We usually creasingly complex and eventually cortex mostly autonomously, but al- only speak of the chewing organ and led to the development of a new ways fed back by sensible, sensory this concept alone seems to reduce mandibular joint, which is still centers (that process peripheral in- our operating field to restoring the found in mammals (mammalia) formation). function of “chewing”. However, the today. The original hinge joint The basic functions of the stoma- stomatognathic system has many evolved to become the ossicles of the tognathic system mentioned above other functions and plays a key role middle ear (ossicular chain). The os - are complemented by the formation in the evolution from hominoids to seous mandibular corpus is a meso- of sounds in mammals (mammalia) homo sapiens as opposed to other derm derivative that has a growth and birds (aves) [2]. The main focus organ systems. It consists of numer- center specifically in the area of the of the development of a sound is un- ous structures that form a complex ascending jawbone that links the doubtedly in the larynx, where its cypernetic regulatory circuit (Fig. 1a, condyle and caput mandibulae to specific structure makes a modu- Fig. 1b), which themselves show os - the structures of the neurocranium. lation of sounds possible. But also the seous, chondral, ligamentary, muscu- It is characteristic for our mandibular shape of the oral cavity plays a key lar, fascial, organic and neuronal con- jaw that osseous and cartilaginous role in sound formation and func- nection with other systems. structures such as condyle, condylar tions as a resonance space. The de- The primary functions of the sto- cartilage, articular disk and articular sign and modification of the oral cav- matognathic system were food in- capsule evolve in parallel and cluster ity with tongue, teeth, cheek and lip take, defense and the presentation of together. This evolutionary process muscles, muscles of the soft palate threatening gestures in order to es- required perfect coordination of all and the mucosa all contribute signifi- tablish a social ranking order. Pres- growth processes considering the cantly to the specific formation of ently, we find these simple functions spatial limitation of the fast evolving sounds. Only in humans, the in various phylogenetic inferior ani- structures of the neurocranium and formation of sounds has evolved to mal species. From the ectoderm, viscerocranium as well as the neck. It the level of language. According to fangs evolved from what used to may explain the difficulty in diag- Popper [7] we differentiate the fol- originally be skin scales to capture nosis of dysfunction of the stoma- lowing stages of speech/articulation: and fixate food [8]. A simple hinge tognathic system. Due to its many – Stage 1: Expressive or sympto- joint with a one-dimensional flap individual functions, the stomato - matic function: The living being motion was sufficient for this func- gnathic system in the human organ- expresses inner emotional states Translation: Yasmin Schmidt-Park Citation: Behr M, Fanghänel J: The impact of the stomatognathic system on the development of human beings. Dtsch Zahnärztl Z Int 2019; 1: 171–174 DOI.org/10.3238/dzz-int.2019.0171–0174 © Deutscher Ärzteverlag | DZZ International | Deutsche Zahnärztliche Zeitschrift International | 2019; 1 (5) 172 PRACTICE MINIREVIEW such as fear or well-being, for example the purr of a cat – Stage 2: Signal or signal-trig- gered function: For example, warning cries of birds that alert their fellow species to warn of danger and to trigger flight be- havior. – Stage 3: Descriptive function: items or conditions, such as the current or future weather, can be described to other living beings using articulation and can therefore be communicated – Stage 4: Argumentative function: Exchange of abstract processes that can occur in different time levels (past, present, future) and spaces. Critical evaluations, Figure 1a Cybernetic regulatory circuit and neuromuscular control of masticatory plans and decision making on function. occurrences in the environment can be articulated. Stage 3 and particularly stage 4 are only present in humans. Even chim- panzees (pan), our closest relatives are only capable of creating stage 1 and 2 sounds. The attitudes differ on how far the primate morphology of the larynx does not allow speech. Unlike Lie- bermann [6], Tobias [10] shares the view that fundamentally, the higher primates’ morphological differences in the upper airways are not an explanation for their inadequate speech functions. In a study in the USA a chimpanzee baby and a human baby were raised in the same family [4]. The surroundings and support were practically identical for both infants. While the human baby practiced its speech function through continuous babble Figure 1b Cybernetic regulatory circuit and neuromuscular control of speech function. and sound formation, the chimpanzee baby was mostly mute. It never learned our stage-3-speech function, to name objects in the room, and es- we differentiate a dominant and a metic and computerized functions. pecially not stage-4-speech function, non-dominant brain half [2, 5]. The The right cerebral hemisphere is which the human baby learned in the dominant left cerebral hemisphere linked to consciousness (however, course of its development. has a connection to our self-con- not self-consciousness). It processes Eccles sees an explanation of this sciousness as an independent person. non-verbal information, tactile geo- situation in brain development as It analyzes verbal, linguistic descrip- metric information e.g. of the room well. Brain size does not solely play a tions, conceptual similarities, ana- and analyzes image and space pat- key role. In humans – approximately lyzes time and is capable of arith- terns, visual similarities and can carry 30.000 years ago – the development metic and computerized functions. out syntheses on this time period. of both brain halves took a new di- (Fig. 2). The dominant left cerebral We owe the ability of speech of rection into cerebral hemispheres. hemisphere has a connection to our stage 3 and 4 cross-modal links of dif- The brain halves, which would have self-consciousness as an independent ferent sensory centers of both hemi- practically fulfilled inversely identical person. It analyzes verbal, linguistic spheres as well as specially developed functions, specialized on the contrary descriptions, conceptual similarities, areas of the left hemisphere. These are to other mammals. In homo sapiens, analyzes time and is capable of arith- the anterior speech cortex (Broca’s © Deutscher Ärzteverlag | DZZ International | Deutsche Zahnärztliche Zeitschrift International | 2019; 1 (5) PRACTICE MINIREVIEW 173 Figure 2 Cortical language fields of the left dominant cerebral hemisphere. The left cerebral hemisphere is depicted laterally (from below) and medially (from above). Re-drawing after [2]. speech area), the upper speech cortex opment encouraged it and made it and especially the posterior speech possible to develop advantages of al- cortex (Wernicke’s speech area) (Fig. truistic action and the value of cul- 2). In the animal kingdom tactile, vi - tural effort (Fig. 4). The potential of sual or auditory sensory stimuli are al- human evolution exponentiated ex- ways connected with a “limbic stimu- plosively. It is no longer dependent on lus” [2], and therefore determine the random “improvements” through living beings action. Human beings mutations in genetic material, and is can also associate not-limbic sensory no longer reliant on other living stimuli, become conscious of them beings [2]. and can orient their actions accord- The development of these ingly. Using language, the division be- unique, new cross-modal links are tween different senses can be over- readable in the human brain’s to - come. It helps us to merge different pography (Fig. 2). We find the ante - sensory modalities into one unit, rec- rior language center directly before ognition and experience. Teuber [9] zones that are responsible for con- expressed this fact in the following trolling relevant muscles. In the case way: “Language frees us to a great ex- of motoric aphasia the cause of the tent of the tyranny of the senses.” malfunction is in the use of the Through language, human beings muscles used for articulation, rather have succeeded to formulate, evalu- than their paralysis. The posterior ate, and share sensory experiences language center of the left cerebral with others, or rather, to profit from hemisphere is crucial for the initi- the wealth of experience of other ation, execution and understanding people. Through language, the bene- of language. If this structure is dis- fits of the upright walk (verticali- rupted, neither written nor spoken sation) and an subsequent modifica- language can be understood. When tion of the skull base could fully un- looked at in a side by side compari- fold (Fig. 3) [3], which leaves the son, a hypertrophy of the structure (Fig.

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