Deane Juhan > Quotes

“Our flesh is like silly putty that distorts when it is ignored. We are constantly obliged to actively participate in its formation, or else it will droop of its own weight and plasticity.
This incessant formation we cannot stop. We can only make the choice to let it go its own way - directed by genetics, gravity, appetites, habits, the accidentals of our surroundings, and so on - or the choice to let our sensory awareness penetrate its processes, to be personally present in the midst of those processes with the full measure of our subjective, internal observations and responses, and to some degree direct the course of that formation.

We do not have the option of remaining passively unchanged, and to believe for a moment in this illusion is to invite distortions and dysfunctions. Like putty, we are either shaping ourselves or we are drooping; like clay, we either keep ourselves moist and malleable or we are drying and hardening. We must do one or the other; we may not passively avoid the issue.”
― Deane Juhan, Job's Body

“Hence the term “voluntary muscle” is in many ways a figure of speech. I can consciously command a movement, but I cannot consciously command the recruitment of every muscle fiber which must be used, nor the precise order of their contractions and lengthenings which actually produce the desired effect. This is to say that every consciously willed movement is always conditioned by two things: genetically established organization and habitual usage. Our genetic organization is quite plastic, open-ended, filled with potential variations in behavior; on the other hand, habitual usage can become just as limiting as it is convenient, and can become a tyrant to exactly the degree that it becomes practiced, automatic, unconscious. We are free to train ourselves to act differently, but it is very difficult to suddenly act differently than we have been trained. The tendencies in our motor behavior created by genetically determined patterns and by habitual usage do not lie within the muscle cells, nor even in the motor neurons that unite them into motor units. The search for the organizational factors of purposeful muscular control—whether it be action or relaxation—takes us deeper and deeper into the central nervous system, where we find that every muscular response is built up, selected, and colored by the totality of our neural activity, both conscious and unconscious.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The pathways with axons pointed towards the periphery, and which conduct impulses outward, are called efferent pathways. Their origins can ultimately be traced to the motor cortex, next to the sensory cortex at the top of the brain. Their axons descend the spinal cord and fan out into the body, terminating in synapses with the striated skeletal and cardiac muscles, and the smooth muscles of the vessels, internal organs, and glands. They are alternately termed the motor pathways. Their role is to carry out to the body, from every level in the nervous system, all of the impulses which control the appropriate contraction and lengthening of the entire musculature. Their signals are translated into the various behavioral effects which the mind chooses in response to input.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The great significance of the facts that we all eat, grow, reproduce, react alike to pleasure and pain, and are linked together in the marvelous interdependencies of physical nature is all too often stifled and buried under the less fundamental observations that we do not all think or feel or worship in exactly the same ways. And, lost in our thoughts, we often omit to do those things that would turn our best ideas into physical realities, because we can easily forget that “the activities of the nervous system can have no external significance until they are expressed to our fellow men by muscular activity, be it action, writing, or speech”12. Helping to correct the solipsistic tendencies of abstract contemplation is one of the most important roles of bodywork.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The path of an impulse through the nervous system is not linear, from stimulation to sensation to motor response; it is always circular, each motor response in turn providing stimulation which colors the sensations, which alter the subsequent motor responses, and so on and on and on. My own tissues are among the objects that touch my awareness, and my own muscular responses are continually a part of the creation of sensory information about the world that floods my central nervous system. Movement itself is the factor which unites the two halves of my nervous system into a unified relationship of continually mutual reciprosity—“Perception and motor answer are the two sides of the unit behavior.”1”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“This sensorimotor interplay, movement and contact, is the basis for learning any new skill. This is what is going on, for instance, when infants are indulging in the endless exercise of vocal movements—spitting, smacking, blowing, cooing—what we call “babbling.” In the course of these vocal tract gestures, [the infant] produces sound patterns which resemble the vowels and consonants of his parents’ language as well as those of many foreign languages. Most importantly however, he is being flooded with sensory feedback. His every unintentional variation of vocal pitch, quality, or loudness, every movement of the tongue or lips in the midst of a vocal sound, produces simultaneous changes in sound and in tactile-proprioceptive sensation. Perhaps one reason why infants can master some simple speech movements, complex as they are, by nine or ten months is simply this fact of inevitable, simultaneous auditory and tactile-proprioceptive feedback from the vocal tract.5 Children who have poor sensation in their mouths and lips do not learn to talk normally, no matter how much training they are given. “To learn normal motor patterns for speech a child must not only hear the speech of others, but also he must hear and feel his own speech movements.”6”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“It is really just as accurate to say that it has been the increasingly numerous and complex sensations associated with locomotion that has led to the development of the brain, as it is to state the case the other way around. As with all matter, usage dictates shape, specific function produces specific form. Thus as the animal kingdom has moved forward from jellyfish to worms to vertebrates, new behavior patterns have bodied forth new neural structures and circuits, just as surely as new neural mechanisms have opened up new modes of behavior. Once such a pattern has been established, the increasing sensory experience which arises from the assumption of a terrestrial existence is associated with further increases in the size and complexity of the brain, so that more complex behavior patterns are possible. Thus in man the assumption of the erect posture and the freeing of the upper limb from its supporting functions, with the consequent development of the hand as a potent new sensory organ, may well have played a significant part in the growth of the human nervous system to its present complexity.9 And note well: In this development, it has been the kind and the amount of sensory input which have been major factors in these profound changes in the structure and function of the central and peripheral nervous systems. Deep neuromuscular patterns most certainly are, and always have been, wide open to the influences of specific qualities and quantities of touch. In this context, it does not seem at all impossible that effective bodywork could foster new levels of awareness, new patterns of response, and even new neural conditions that would influence all future responses in an individual. The entire developmental history of the centralization and encephalization of the human nervous system is evidence of the potent organizing powers of touch.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“I can bring a glass of water smoothly to my lips because practice has taught me just how much contractile effort and speed is necessary to lift it and carry it through the air without either dropping it or throwing the water towards the ceiling. This familiar feel for the resistance of the glass of water, and for the appropriate muscular effort to both overcome that resistance and remain in constant control, are functions of the variable settings of the inhibitory response of the Golgi tendon organs. And I use this reflex mechanism every time I use a screwdriver or a wrench, row a boat, push a car, do a push-up or a deep knee bend, pick up an object—in short, every time I need a specific amount of effort delivered in order to accomplish a specific task—any time “too much” is just as mistaken as “too little.” This includes, of course, almost all the controlled uses to which I put my muscles. Now in order to be helpful in all situations, this variable setting of the tension values which trigger the reflex must be capable of both a wide range of adjustment and rapid shifts. Objects that we need to manipulate with carefully controlled efforts may be small or large, light or heavy. Building a rock wall can require just as much finesse and balance as building a house of playing cards, but the levels of tension which require equally sensitive monitoring are very different in each case. Since these relative tension values can be altered rapidly at will, and are refined with practice, it seems evident that they can be controlled by higher brain centers. This is presumably done through descending neural pathways which can generate impulses that either facilitate or inhibit the action of the Golgi/motor neuron synapses. In this way, control signals from higher nervous centers could automatically set the level of tension at which the muscle would be maintained. If the required tension is high, then the muscle tension would be set by the servo-feedback mechanism to this high level of tension. On the other hand, if the desired tension level is low, the muscle tension would be set this level.9”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The lowest level of this modifying intermediate network is the spinal cord. The cord still possesses many features that were first developed in the segmented earthworm. It is largely made up of neurons completely contained within it, which form bridges between the sensory and motor elements throughout the whole body. Each peripheral nerve trunk still innervates a specific segment of the body, and still joins the cord at a specific level, creating a ganglion. Sensory signals entering into a single segment may be processed by its own ganglion, and cause localized motor response within the segment; or the signals may pass to adjacent segments, or be carried even further up or down the line, involving more ganglia in a more widely distributed response. In this way, the cord can monitor a large number of sensorimotor reactions without having to send signals all the way up to the brain. Thus stereotyped responses can be made without our having to “think” about them on a conscious level. Most of these localized and segmentally patterned responses are not the result of experience or training, but of genetically consistent wiring patterns in the internuncial network of the cord itself. These basic wiring patterns unfold in the foetus during the “mapping” process of the nervous system, and they have been pre-established by millions of years of development and usage. The spinal cord can be surgically sectioned from the higher regions of the internuncial net, and the experimental animal kept alive, so that we can isolate the range of responses that are primarily controlled by these cord reflexes. Almost all segmentally localized responses can be elicited, such as the knee jerk caused by tapping the tendon below the knee cap, or the elbow jerk caused by tapping the bicep tendon. These simple responses can also be spread into other segments, so that a painful prick on a limb causes the whole body to jerk away in a general withdrawal reflex. The bladder and rectum can be evacuated. A skin irritation elicits scratching, and the disturbance can be accurately located with a paw. Some of the basic postural and locomotive reflex patterns seem to reside in the wiring of the cord as well. If an animal with only its cord intact is assisted in getting up, it can remain standing on its own. The sensory signals from the pressure on the bottoms of the feet are evidently enough to trigger postural contractions throughout the body and hold the animal in the stance typical of its species. And if the animal is suspended with its legs dangling down, they will spontaneously initiate walking or running movements, indicating that the fundamental sequential arrangements of the basic reflexes necessary for walking are in the cord also. All of these localized and intersegmental responses are rapid and automatic, follow specific routes through the spinal circuitry, and elicit stereotyped patterns of muscular response. Most of them appear to consistently use the same neurons, synapses, and motor units every time they are initiated.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The Golgi tendon organs are found among the collagen bundles of the tendons, in the border zone where the muscle fibers are attached to the tendons. Although they are located in the connective tissue of the tendon rather than in the midst of the muscle cells, they are, like the spindles, minute gauges for the efforts of the alpha muscle fibers.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“There is another way of separating the whole system into major divisions, divisions which are not as visually obvious as peripheral and central, but which in some ways more accurately represent actual functional distinctions. Roughly half of our neurons have their dendrites reaching out towards the surfaces of our organisms, and their axons reaching in towards the core. This means that they propagate their action potentials in an inward—centripetal—direction. The other half are arranged with their dendrites reaching in towards the core and their axons reaching out towards the periphery; these neurons send their action potentials in an outward—centrifugal—direction. The pathways created by these differently oriented neurons do not stop at the threshold of the central nervous system; both can be traced from the periphery to the spinal cord, throughout the cord’s length, through the brainstem and the hypothalamus, and finally to the literal summit of the brain, the sensory and motor cortexes. This division is based, then, not on the separation of these different anatomical structures, but upon the direction of action potential flow through those structures and the specific pathways they take.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The addition of new neurons to handle new operations is only a part of the process of encephalization. The other parts are the gradual modification of ancient reflex patterns, the diversion of neural flow from the older channels, and the creation of new chains of command in the ordering of specific sequences of motor activity. The net result has been that the higher cognitive centers have become increasingly influential, while the older time-worn patterns have become less authoritative, more variable. Conscious mental states have begun to condition the system just as much as the system conditions these higher states of consciousness. But new powers and new subtleties do not appear without new complications, new conflicts. In bodywork we continually feel the muscular results of the intrusion of newer mental faculties into older, more stable response patterns. A good deal of the work is simply reminding minds that they are supported by bodies, bodies that suffer continual contortions under the pressure of compelling ideas and emotions as much as from weight and physical stresses, bodies that can and will in turn choke off consciousness if consciousness does not regard them with sufficient attention and respect. It is possible—in fact it is common—for the mass of new possibilities to wreak havoc with older processes that are both simpler and more vital to our physical health. Thus with our newer powers we are free to nurture ulcers as well as new skills, free to inspire paranoia and schizophrenia as well as rapture, free to become lost in our own labyrinths as well as explore new pathways. We have unleashed the human imagination, to discover that there is no internal force as potent to do us either good or ill. With the addition of these new cortical faculties, the quality of our muscular responses—from digestion, to posture, to locomotion, to expressive gesture, to chronic constriction—is dependent not only upon stimulations from the environment, and not only upon patterns characteristic of the species, but also upon individual experiences, memories, unique associations, personal emotions, expectations, apprehensions, the entire legion of personal psychological states.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Because the efferent pathways lead directly to muscle cells, it is tempting to regard their activities as the cause of our motor behavior. But they are nothing of the kind until they are themselves stimulated by their numerous connections with the spinal cord and the brain (remember that an estimated fifteen thousand axons can converge upon a single terminal motor neuron). And these deeper, more central activities are in turn initiated and directed to a large degree by afferent, sensory stimulation. In bodywork, it is often problematical aberrations of motor response that we want to change, but sensory affects are our only means of doing so. We know we are doing our job when our hands feel jumpy reflexes smoothing out, high levels of tone decreasing, pliability returning to stiffened areas, range of motion increasing. These are all quantitative and qualitative shifts in motor activity. But we also must know that it is only our skilled manipulation of sensory stimulation which can accomplish these things, because it is primarily sensory associations which have conditioned the muscular patterns in the first place. Until the body feels something different, it cannot act differently. Only when contact with the world is perceived as something other than jabs and buffets can the organism respond with something other than aggression and defense.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Relative levels of activity in the pons and the brain stem directly relate to the general level of arousal of the entire nervous system, and to the level of tonus of the musculature as a whole. The natural suppression of activity in this area corresponds to sleep; the chemical suppression of the same activity is anaesthesia. In addition to general arousal, some specific emotional states can be produced in an animal with only a lower brain and cord intact: general excitement, sexual arousal, anger, and typical responses to pain or pleasure. (This list of functions is by no means complete; it is intended only to convey an idea of the kind of organization and selection which the lower brain adds to that of the spinal cord.)”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The hollowness of the collagen fibril is one of its fascinating aspects. Most tubes in the body circulate fluids of one kind or another, and this one seems to be no exception. These billions of fine tubules constitute one of the circulatory systems of the body, along with those for blood and for lymph. What one researcher reports finding inside the collagen fibrils is not blood, nor lymph, nor ordinary ground substance, but rather cerebrospinal fluid!17 This finding suggests that the connective tissue framework may play a role in the body’s chemical messages and balances that is even more sophisticated than we can presently document.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“In addition to this, chronically high levels of pressure upon nerve trunks is itself detrimental to their electrical activity, apart from such general circulatory complications. Some researchers have estimated that five pounds of pressure for five minutes on a nerve trunk can reduce its transmission efficiency by as much as forty per cent. In time, the results of these pressures can be the sharp ache of sciatica generated by the rotator muscles of the hip, numbness or tingling sensations in the hands from the neck muscles clamping down on the brachial plexus, chronic pains in the face and the head from pressure on the trigeminal nerve, and so on. And of course, since the nerve supply to internal organs can be similarly effected, such chronic constrictions can bring along a wide range of organ dysfunctions in its train of events as well—organ dysfunctions that can be extremely difficult to diagnose and treat because no “disease” state exists and no observable damage has been done to specific organ tissues. Indeed, the complications for circulation and neural transmission which follow in the wake of chronic muscular contraction present some of the gravest potential dangers for the health of the nervous system, and of the body as a whole. Loss of neural efficiency means a less and less vivid reception of the messages that the nerves convey, both from the sensory endings and to the motor units. And areas of the body that are not adequately irrigated stagnate precisely like the choked and swampy backwaters of a sluggish stream, creating septic situations that are ripe for discomfort, disease, and decay. Nor should we forget the facts that increasingly constricted capillaries require higher and higher blood pressure to make them function at all, and that once they either collapse from the muscles squeezing them or burst from increased blood pressure, they will be replaced with scar tissue and not by new capillaries, thus making the local loss permanent.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The lower brain—including the pons and the brain stem—is primarily responsible for our “subconscious” processes, those many activities which are more complex and integrated than cord reflexes, but of which we are seldom aware. To begin with, many more sequences of simple reflexes are possible if the pons and the stem are left intact with the cord. The lower brain clearly assists the cord in fine-tuning responses, and in arranging them in the appropriate order so that they produce more integrated behavior. The complicated sequences of muscular contraction necessary for sucking and swallowing, for example, are monitored at this level. These are skills with which a human infant is born; their underlying circuits—and even more importantly, the correct sequence of operation of these circuits—is a product of early genetic development, not individual experience and learning. In general, the lower brain seems to share many of the “hard-wired” features of the spinal cord. Axons and synapses form organizational units that appear to be consistent for all individuals of the same species, and their activation produces identical, stereotyped contractions and motions. But the additional complexities of the lower brain appear to enable it to pick and choose more freely among various possible circuits, and to arrange the stereotyped responses with a lot more flexibility than is possible with the cord alone. For instance, it is in the lower brain that information from the semi-circular canals in the inner ear—the sensory organ for gravitational perceptions and balance—is coordinated with the cord’s postural reflexes. A stiff stance can be elicited from these postural reflexes by merely putting pressure on the bottoms of the feet; by adding information concerning gravity and balance to this stance, the same reflex cord circuits may be continually adjusted to compensate for shifts in equilibrium as we tilt the floor upon which the animal is standing, or as we push him this way or that. A rigid fixed posture is made more flexible and at the same time more stable, because compensating adjustments among the simple postural reflexes is now possible. The lower brain coordinates the movements of the eyes, so that they track together. It directs digestive and metabolic processes and glandular secretions, and determines the patterns of circulation by controlling arterial blood pressure. And not only does it give new coordination to separate parts, it influences the system as a whole in ways that cannot be done by the segmental arrangement of the cord.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“At the peripheral end of these parallel circuits, the motor nerve axon attaches to a muscle cell by a motor end plate, creating a neuromuscular synapse. Each muscle cell receives one, and only one, end plate. Each motor axon, on the other hand, has a number of branches and attaches end plates to several different muscle cells in the same area. So each muscle cell receives commands from one nerve cell only, while each nerve cell stimulates several muscle cells. A single motor neuron with its group of attached muscle cells is called a motor unit.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Any general movement is made up of hundreds of small contractile movements, each one arranged in a closely timed sequence to contribute its increment to a smooth and controlled gesture. These small local contractions are generated by the stimulation of the alpha motor neurons in the spinal cord which connect to their individual motor units. It appears to be the job of the basal ganglia to orchestrate the basic selection of the appropriate motor neurons, initiate their stimulations in the proper sequence, and direct their precise timing. Some of these movement patterns, such as swallowing, are fully established in the basal ganglia at birth; others, such as walking, are the result of long years of practice. Each of these ganglia seem to add a specific quality to any general movement, qualities that are notably absent or exaggerated when the activity of one of the ganglia is out of balance with the others. A few examples will help to indicate how each ganglia adds its organizational component to a successfully controlled movement.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“So it is necessary that we have a means of monitoring the tension developed by muscular activity, and equally necessary that the threshold of response for the inhibitory function of that monitor be a variable threshold that can be readily adjusted to suit many purposes, from preventing tissue damage due to overload, to providing a smooth and delicate twist of the tuning knob of a sensitive shortwave receiver. And such a marvelously adaptable tension-feedback system we do have in our Golgi tendon organs, reflex arcs which connect the sensory events in a stretching tendon directly to the motor events which control that degree of stretch, neural feed-back loops whose degree of sensory and motor stimulation may be widely altered according to our intent, our conscious training, and our unconscious habits. This ingenious device does, however, contain a singular danger, a danger unfortunately inherent in the very features of the Golgi reflex which are the cleverest, and the most indispensable to its proper function. The degree of facilitation of the feed-back loop, which sets the threshold value for the “required tension,” is controlled by descending impulses from higher brain centers down into the loop’s internuncial network in the brain stem and the spinal cord. In this way, conscious judgements and the fruits of practice are translated into precise neuromuscular values. But judgement and practice are not the only factors that can be involved in this facilitating higher brain activity. Relative levels of overall arousal, our attitudes towards our past experience, the quality of our present mood, neurotic avoidances and compulsions of all kinds, emotional associations from all quarters—any of these things can color descending messages, and do in fact cause considerable alterations in the Golgi’s threshold values. It is possible, for instance, to be so emotionally involved in an effort—either through panic or through exhilaration—that we do not even notice that our exertions have torn us internally until the excitement has receded, leaving the painful injury behind to surprise us. Or acute anxiety may drive the value of the “required tension” so high that our knuckles whiten as we grip the steering wheel, the pencil suddenly snaps in our fingers, or the glass shatters as we set it with too much force onto the table. On the other hand, timidity or the fear of being rejected can so sap us of “required tension” that it is difficult for us to produce a loud, clear knock upon a door that we tremble to enter.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The pathways with axons pointed towards the core, and which carry impulses inward, are called the afferent pathways. They originate in the various sensory endings of the body—the exteroceptors on the surface, the proprioceptors in the connective tissues (especially the joints), and the interoceptors in the the internal organs. Their final axons terminate in the sensory cortex. They are often referred to as the sensory pathways. Their job is to carry to all the levels of the nervous system information about everything that is affecting the organism—that is, all sensory stimulation. Four of these afferent pathways are short and distinct, arising from the highly localized and specialized areas of the “special senses”—sight, hearing, taste, and smell. The fifth kind of sensory information, that wide array of sensations we refer to collectively as “touch,” converges on the cortex from virtually every surface and cranny of the body. These are the “somatic senses,” and they include all of the pathways and endings which inform us of our internal state of affairs and our relationship to the outside world. The afferent, inflowing pathways of the nervous system constitute one of the principal tools of bodywork. It is by their means that surface contact and pressure enter into the deeper strata of the mind, where genetic potential and sensory experience are fused into behavior and character. Each successive afferent neuron is a finger reaching deeper and deeper into the interior, making its influence felt on all levels which influence behavior. It is sensory input which has conditioned our reflexes, postures, and habits into the patterns in which we find ourselves living. Nothing would seem to be more reasonable than the expectation that different sensory input can recondition these habits and patterns, alter them, improve them. This input can be different both in the sense of being more, giving additional nutritive contact to the various subtle degrees of “deprivation dwarfism,” and in the sense of being more pleasurable, more caring, softening and dissolving compulsive patterns that have been created by pain and stress.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“There is another mechanism which even further selects and distorts incoming sensory information, and which is extremely important to the therapeutic purposes of bodywork. Side-by-side with the ascending dorsal and spinothalamic pathways are descending sensory pathways, outgoing tracts from the brain which are not efferent, which do not contact motor neurons, but which synapse densely with the ascending sensory pathways and exert a centrifugal flow against their incoming sensory information.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Efferent impulses may be conducted along one of two major pathways of motor neurons as they pass from the brain through the cord and out to the muscles, and together these longitudinal pathways provide for the convergence of the influences from all levels of the central nervous system upon the motor units. The fastest of these descending routes is the direct corticospinal pathway. As the name suggests, the cell bodies of this path are in the cortex, and they send their long axons directly through the brain and down the spinal cord without any interruptions. These axons do not form any synapses until they reach their corresponding motor neurons in the cord, and thus they form direct connections between specific cells in the motor cortex and specific motor neurons at each level of the cord, making one-to-one relationships between cortical cells and peripheral motor units. This pathway bypasses most of the intermediate circuitry of the lower brain and the spinal cord. This gives it the advantage of speedy transmission. The axons which are bundled together within it maintain a constant spatial relationship throughout their length, faithfully reflecting the spatial relationships of the cell bodies in the cortex. The longest axons, reaching all the way to the end of the cord, lie the closest to the center of the cord, and the progressively shorter axons which synapse to motor neurons in progressively higher segments, are carefully laid down in layers progressively far from the center of the cord, so that a “map” of skeletal muscle relationships is projected onto the motor cortex. This gives a high degree of specificity to this direct corticospinal tract. This direct pathway is the mediator of fine, intricate movements, which require close conscious attention and constantly refined adjustment. When it is severed, actions become clumsier, because the sharp edge of delicate conscious control is missing.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“In still higher invertebrates, such as the earthworm, the diffuse nature of this intermediate net disappears, and it is now organized into a distinct nerve cord running the length of the worm. Sensory elements become even more differentiated, and the special senses—light sensitivity, smell, taste, gravitational orientation—become even more concentrated at the head end, swelling the size, capacity, and sophistication of the head ganglion even further. The sensory elements still originate in the worm’s skin, but now they send their axons directly to the central cord, without contacting any muscle cells; and for the first time distinct motor neurons appear, sending their axons out from the central cord to the muscle cells in the body. And in addition, we encounter another type of nerve cell for the first time, cells which are contained wholly within the head ganglion and the cord, cells which are neither really sensory nor motor, at last purely internuncial in their functions. They are arranged into afferent and efferent pathways, running the length of the cord towards and away from the head ganglion.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The circulation of the fluids within the long, thin tubes of the axons is equally important to the proper conditions of the nerves’ membranes and the propagation of action potentials, and inadequate pumping action of the surrounding muscles reduces this hydraulic flow as well. Chronically tense and constricted muscles can complicate things in an even worse fashion. Not only is fluid circulation in and around nerve cells curtailed, but the capillaries which supply the nutrition and carry off the waste products are squeezed tightly as well. At the same time, the contracting muscles are producing increased waste products and demanding increased nutrients from capillaries that are less able to supply them. This creates both an oxygen shortage and a waste build-up in the area, both of which are directly toxic to the nerve cells, irritate them, and contribute to even further muscular contractions.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“These increases in brain cholesterol and pituitary activity were clues that were rich in their implications, and in the late 1960’s a research team at the University of California at Berkeley began to look for specific differences in the neural structures of gentled and ungentled rats. They found that greater tactile stimulation resulted in the following differences: These animals’ brains were heavier, and in particular they had heavier and thicker cerebral cortexes. This heaviness was not due only to the presence of more cholesterol—that is, more myeline sheaths—but also to the fact that actual neural cell bodies and nuclei were larger. Associated with these larger cells were greater quantities of cholinesterase and acetylcholinesterase, two enzymes that support the chemical activities of nerve cells, and also a higher ratio of RNA to DNA within the cells. Increased amounts of these specific compounds indicates higher metabolic activity. Measurements of the synaptic junctions connecting nerve cells revealed that these junctions were 50% larger in cross-section in the gentled rats than in the isolated ones. The gentled rats’ adrenal glands were also markedly heavier, evidence that the pituitary-adrenal axis—the most important monitor of the body’s hormonal secretions—was indeed more active.34 Many other studies have confirmed and added to these findings. Laboratory animals who are given rich tactile experience in their infancy grow faster, have heavier brains, more highly developed myelin sheaths, bigger nerve cells, more advanced skeletal muscular growth, better coordination, better immunological resistance, more developed pituitary/adrenal activity, earlier puberties, and more active sex lives than their isolated genetic counterparts. Associated with these physiological advantages are a host of emotional and behavioral responses which indicate a stronger and much more successfully adapted organism. The gentled rats are much calmer and less excitable, yet they tend to be more dominant in social and sexual situations. They are more lively, more curious, more active problem solvers. They are more willing to explore new environments (ungentled animals usually withdraw fearfully from novel situations), and advance more quickly in all forms of conditioned learning exercises.35 Moreover, these felicitous changes are not to be observed only in infancy and early maturation; an enriched environment will produce exactly the same increases in brain and adrenal weights and the same behavioral changes in adult animals as well, even though the adults require a longer period of stimulation to show the maximum effect.36”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“First of all, the tone of my muscle cells must hold my skeleton together so that it neither collapses in upon my organs nor dislocates at its joints. It is tone, just as much as it is connective tissues or bone, that is responsible for my basic structural shape and integrity. Secondly, my muscle tone must superimpose upon its own stability the steady, rhythmical expansion and contraction of respiration. Third, it must support my overall structure in one position or another—lying, sitting standing, and so on. Finally, it must be able to brace and release any part of the body in relation to the whole, and to do this with spontaneity and split-second timing, so that graceful, purposeful action may be added to my stability, my posture, and my rhythmic respiration. It is no wonder we find that such large portions of our nervous systems are so continually engaged in controlling the maintenance and adjustments of this tone. The entire system of spindle cells, with both their contractile parts and their anulospiral receptors, the Golgi tendon organs, the reflex arcs, much of the internuncial circuitry of the spinal column, and most of the oldest portion of our brains—including the reticular formation and the basal ganglia—all work together to orchestrate this complex phenomenon. We have, as it were, a brain within our brain and a muscle system within our muscle system to monitor the constantly shifting values of background tonus, to provide a stable yet flexible framework which we are free to use how we will. Nor is it a wonder that these elements and processes are normally controlled below my level of consciousness—if this were not the case, walking across the room to get a glass of water would require more diversified and minute attention than my conscious awareness could possibly muster. It is the old brain, along with the even more ancient spinal cord, that are given the bulk of this task, because they have had so many more generations in which to grapple with the problems and refine the solutions. Millions upon millions of trials and errors have resulted in genetically constant motor circuits and sensory feedback loops which handle the fundamental life-supporting jobs of muscle tone for me automatically. Firm structure, posture, respiratory rhythms, swallowing, elimination, grasping, withdrawing, tracking with the eyes—all these intact and fully functional activities and more are given to each of us as new-born infants, the legacy of the development of our ancestors.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The cerebral cortex is the newest portion of the nervous system, and in man it has developed into the largest portion. In its anatomical connections, it is clearly an outgrowth of the areas of the brain directly beneath it—the hypothalamus—and in its functional aspects it represents a great leap forward for the lower brain’s abilities to integrate sensory information and to select and order new motor responses. It is an immense addition to the internuncial net; fully three-quarters of the cell bodies in the human central nervous system are contained in the cortex. And the horizontal interconnections between these cells are far more dense than those in the cord or the lower brain. Schematically, it resembles a ball of cotton fuzz much more than it resembles even the most complex man-made electrical circuitry. The cortex appears to be primarily a vast storage center of information and associations, preserved bits of experience which can be suppressed or recalled to modify behavior in truly innumerable ways.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Thirdly, more ATP is necessary for the “pumping” of the calcium ions back into the sarcoplasmic reticulum, so that contraction can cease when neural stimulation ceases.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Calcification At a certain point in the cartilage’s development (and this moment is different for different bones in the body), the chondroblast cells, which have been secreting cartilage, undergo a physical and functional change. They expand in size, stop producing cartilage, and begin to secrete the chemicals which precipitate into crystals the dissolved mineral salts delivered by the blood.”
― Deane Juhan, Job's Body: A Handbook for Bodywork