Job's Body 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

“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 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.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“What we can say about the organization of the nervous system has largely been inferred from dissection, electronic or surgical probing, comparative anatomical studies of dead specimens, and various experimental techniques to isolate particular kinds of learning and behavior. All these methods are disruptive of normal functioning. They were undoubtedly the only avenue open to us in which to begin our internal investigations, and they have in fact yielded a considerable amount of interesting information. But we must always approach this information with our means of getting it in mind. When we dissect and isolate in order to discern more clearly, we have altered our material so that we may simplify it, created anatomical distinctions where there may be no functional ones, separated elements which have no useful existence apart from one another, and we are therefore in constant danger of drawing conclusions which satisfy the limitations of our procedure rather than the realities of the situation we are investigating.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Dispassionate scrutiny may well help us to find the sort of person we should fall in love with in order to have the best chances of being happy; but by itself it does not do much to make us fall in love. There are precise laws of physics that can describe mathematically all of the forces at play as I pedal and turn my bicycle, but it is the feel for the thing, and not my knowledge of mathematics, that allowed me to learn to ride it. No amount of biochemical facts is sufficient to prevent chronic stress from producing ulcers in my stomach. And no accumulation of facts about the way things are can ever dispel the mystery of why there is something rather than nothing.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The sensory roles of the anulospiral receptor and the tendon organ are absolutely central in this process of exerting and adjusting muscle tone. These devices establish the “feel” for length and tension, and it is this feeling which is maintained by the gamma motor system, the reflex arcs, and the alpha skeletal muscles. All of my muscle cells—both alpha and gamma—are continually felt by the mind as they work, whether most of these “feelings” ever reach my conscious awareness or not. And it is primarily these muscular feelings which supply my central nervous system with the constant information necessary to successfully combine the demands of free motion with those of basic structural stability. The sophistication required for this maintenance of structure and flexibility can be appreciated if we remember that almost any simple motion—such as raising the arm out to the side—changes either the length or the tension values in most of the body’s muscle cells. If one is to avoid tipping towards the extended arm, then the feet, the legs, the hips, the back, the neck, and the opposite arm all must participate in a new distribution of balance created by the “isolated” movement of raising the arm. The difficulties experienced by every child learning to sit, to stand erect, and to walk with an even gait attest to the complexity of the demands which these shifts in balance and tone make upon us. The entire musculature must learn to participate in the motion of any of its parts. And to do this, the entire musculature must feel its own activity, fully and in rich detail. Competent posture and movement are among the chief points of sensory self-awareness. The purpose of bodywork is to heighten and focus this awareness. It is the child’s task during this early motor training to experiment by trial and error, and to set the precise lengths and tensions—and changes in length and tension—in all his muscle fibers for these basic skills of standing and walking. This is the education of the basal ganglia and the gamma motor system, as learned reflex responses are added to our inherited ones. The lengths and rates of change of the spindle fibers are set at values which experience has confirmed to be appropriate for the movement desired, and then the sensorimotor reflex arcs of the spindles and the Golgis command the alpha motor nerves, and hence the skeletal muscles, to respond exactly to those specifications that have been established in the gamma system by previous trial and error. And this chain of events holds true not only for the actual limb being moved, but for all other parts of the musculature that must brace, or shift, or compensate in any way. In this complicated process, the child is guided primarily by sensory cues which become more consistent and more predictable with every repetition of his efforts.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The evolution of hundreds of thousands of generations has established the necessary muscle lengths and tension loads in order to keep my joints together and to support my structure against the pull of gravity. This information appears to be stored in some form in the brainstem—particularly in the basal ganglia—and transferred genetically from one generation to the next. The whole gamma motor system of the individual then uses this information to adjust the lengths of his muscle spindles appropriately, which in turn adjust the lengths and tensions of his skeletal muscles throughout the reflex arcs.”
― 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

“These two primary reflex arcs—the spindle and the Golgi—are the principal sensory devices which the nervous system uses for the enormously complicated task of maintaining and adjusting the appropriate levels of muscle tone throughout the body. The normal tone of a muscle is dependent upon the simple stretch reflex, through which the the sensory endings in a muscle, stimulated by even the slightest stretching of the muscle, initiate a segmental reflex increasing muscle tone.11 The muscle spindle, whose associated reflex arc tends to excite alpha motor neurons and their motor units, is complimented by the Golgi tendon organ, whose reflex arc tends to inhibit the same alpha neurons and motor units. Between the two of them, they produce a summation of excitation and inhibition on the alpha neurons which keeps the active muscle fibers within a narrow range of tensional forces—just the right amount to stand, to lift a book, to hold a glass. Now the problem of maintaining this precision is such a complex one not only because there are so many muscle cells in the body to monitor, but also because proper muscle tone must accomplish so many different things. It must be able to shift its various tensional values in the various parts of the musculature back and forth so rapidly in order to do all of my muscular tasks competently.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Just as the globus pallidus fixes various body parts in particular positions, so does the striate body initiate and monitor many stereotyped movements. Cats and dogs and horses and pigs all graze and chew, prick up their ears at a new sound, coordinate various gaits, and so on. Humans also share a wide range of stereotyped movements, similar in their features because they are designed to accomplish the same things for each individual. And further, we have noted that although both dogs and cats do many similar things—sitting, walking, drinking, jumping, grooming, and the like—they each do them in distinctly canine or feline ways. Every species has a way of doing the normal tasks of living, a manner of movement that is peculiar to it. A good mime can represent “cat” or “mouse,” or “horse,” or “ape” with a brief imitation of these animals’ manner of movement just as effectively as he could with an elaborate costume. These too are stereotypes of movement. The striate body seems to control a wide range of such movements—individual movements that have common utility, movements which continually correct our balance, movements which are the synchronized background motions’ that necessarily accompany the use of a limb, or movements which establish such standard communications as sexual arousal, docility, fear, anger, or defensiveness. As with fixed positions, in the human being both the repertoire of stereotyped movements and the stereotyped manner in which all movements are done may markedly display habitual preferences built up by compulsions, training, job requirements, and dispositions. And as with chronic fixations, there is the tendency over long periods of repetition to confuse how I do things with who I am. My most common movements, designed to be controlled by my unconscious mind so that I can freely direct my attention elsewhere, become more than stereotypes; they become straight jackets, and I find myself the prisoner of the very unconscious processes which are supposed to protect and liberate me. Re-establishing for the individual the sense of a wide array of equally possible movements is the real significance behind the work of freeing a person from limited neuromuscular patterns.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Over the years, it is the habitual repetition of these preferred fixations which creates the individualized tension patterns in our musculatures, and eventually even alters the thickness of our fascia and the shape of our bones in order to more efficiently accommodate a limited number of positions. As we select postural fixations and become more and more attached to them, their increasing familiarity begins to give us a comforting sensory and psychological stability, a constant norm to which we return as to a favorite jacket or an old friend. Indeed, my favorite fixed positions eventually cease to be something I am doing and become to a large degree what I am. The fixation becomes dominant, and the release more difficult; person, posture, and point of view become firmly welded together, unfortunately limiting all three. And what was a familiar old friend can become an increasingly tormenting millstone around the neck. I find that the position which held me up comfortably for a while cannot do so indefinitely. In fact, there simply is no single position that will support me for indefinite periods of time without producing areas of fatigue, pain, and eventual dysfunction. I need a large repertoire of fixations, so that I am not trapped in the discomforts inherent in any single position. Releasing these compelling fixations is of course one of the principal jobs of bodywork. By manipulating the body so that other positions are concretely experienced, the bodyworker can remind a stiffened back that other positions are in fact possible, that other muscles can take over for a while, that the limitations previously experienced are not anatomical ones. And it is extremely important to remember while manipulating these stiff muscles that the fixation is not in the tissues under my hands, but is deep in the unconscious processes of the mind. My physical contact with the local tissues is merely a means of generating new sensory input into the sensorimotor process; it is the mind that is coordinating this process which must release its hold upon a fixed position.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“In the globus pallidus, all of this sensory information is sifted and selected so that we can appropriately brace some parts of our bodies in order to support the desired movement in other parts. For instance, the back, shoulder, and arm must be suitably braced in order for the fingers to successfully manipulate a pencil on a page. These phenomena of “fixation” seem to be the elements added to coordinated movement by the globus pallidus. If a laboratory animal is electrically stimulated in this ganglion, it will become fixed in whatever position it had achieved at the onset of the stimulation, and it will remain fixed in that position until the stimulation ceases. The possible varieties of these fixations are endless, enabling us to brace all parts of our bodies in any shape the anatomy will allow. Without them, the violinist could not hold his instrument, the marksman could not steady his rifle, the artist could not hold his arm straight to daub the canvas, the host could not pour coffee from the pot. Typically, of course, we do not continue to explore the innumerable fixations of which we are capable. Our habits, our jobs, our social situations, our general dispositions all tend to urge us to prefer certain fixed positions over others. For each of us, our characteristic posture is nothing but a particular fixation to which we return again and again, until the idea that we might in fact stand up in a different way passes out of our conscious consideration.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The substantia nigra is a ganglia that is particularly responsible for the interpretation and coordination of the overall sensory information coming from the muscle spindles and the tendon organs. The totality of this information is crucial to assessing and controlling the changes in lengths of the body’s muscles, the speed with which a movement is occurring, and the actual work-load that is being handled. This, remember, is sensory information that we do not “feel” in the normal sense, but when it is incomplete or scrambled, fine control of movement becomes seriously hampered. The step becomes unsteady, the reach inaccurate; motions become jerky; the limbs may tremble or even oscillate grossly in their attempt to find the correct lengths and speeds. These aberrations are among the symptoms of Parkinson’s disease, a syndrome which appears when the substantia nigra is damaged in any way. Thus the substantia nigra adds to the brain’s overall arousal the specific messages coming from all of the spindles and tendon organs: Which exact motor units are lengthening or shortening, how fast are these changes in length taking place, and how much force is being developed?”
― 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

“The level of activity in this reticular formation reflects an individual’s general state of arousal. Artificial over-stimulation of the entire area does not result in limb-flailing or the exaggeration of particular gestures; instead, it causes a stiffened tetany in all the muscles of the body simultaneously. Everything locks rigidly into place and cannot be moved until stimulation recedes. Conversely, blocking stimulation from reaching the whole area results in a general loss of muscle tone throughout the body, as in our anaesthetized patient. That is, activity in this area as a whole does not command our muscles to produce any particular gesture or assume any particular posture. Rather, general activity here provides the conditions of general muscle tone, sensory awareness, and mental alertness which will support and color whatever postures and gestures are made. The reticular formation cannot issue the command “raise right arm,” but it does help to establish the trembling tension, the calm readiness, or the sluggishness which will characterize how I raise my arm in response to a situation. To direct these general levels of arousal into particular movements requires the next level of the “old” brain, the basal ganglia—the highest level of sensory and motor organization of the gamma motor system.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Much of the bulk of the brain stem is made up of a large area called the reticular formation. The relative amounts of neural activity in this region corresponds to our general levels of arousal, both mental and physical. When we are in deep sleep, the measurable activity in the reticular formation is low; when we are awake and fully alert, reticular activity is relatively high. In fact, going to sleep and waking up are so consistently characterized by markedly decreasing and increasing levels of neural activity in this area that one is tempted to say that sleep is caused by a sharp falling off of neural transmissions in the reticular formation, and awakening is caused by their resurgence.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Like the spinal cord, many of the brain stem’s interconnections are “hard-wired,” and their stimulation initiates obligatory responses that are not unlike those of the spinal reflex arcs. It is these relatively fixed pathways and responses which control the range of behavior and style of movement that are so characteristic of each species; a cat and a small dog have pretty much the same skeletal and muscular structure, yet each moves this structure about in ways which clearly identify it as canine or feline. These distinctly different styles of moving similar physical frames are the result of different patterns of integrating sensory information and of organizing motor commands, primarily in the spinal cord and in the older, “reptilian” portion of the brain—that is, the centers of gamma motor control.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“Thus two different kinds of muscle contractions are possible, each using a different sort of patterning principle to control movements. The motor cortex and the alpha neurons directly cause contractions of the skeletal muscles, contractions which continue as long as the command signals are being sent. The brain stem and the gamma neurons, on the other hand, cause contractions that are mediated through the spindle system, and their commands cease once a predetermined length has been achieved, at which point the stretch reflex arrests further effort. The alpha system organizes its commands in terms of the duration of neural bursts; the gamma system organizes its commands in terms of the starting and stopping lengths of the muscle fibers. In other words, the stimulation patterns which organize the alpha contractions are coded as a function of time—the duration of the bursts coming from the motor cortex. And the patterns which organize the gamma contractions are coded as a function of space, stimulation ceasing when a predetermined length is achieved in the anulospiral gauges.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“We now know that a movement may be initiated by either of these two motor systems. The motor cortex can initiate a voluntary movement without being blocked by the stretch reflex, because when I know that I am going to move in a specific way, then the critical “unexpected” quality of stretching muscle lengths is neutralized. The unconscious gamma command centers in my brain stem can mimic a move directed by my conscious mind, lengthening and shortening its intrafusal cells in concert with the alpha cells around them so that the anulospiral sensory element is not stretched or collapsed during the movement. In this instance, the gamma system follows the lead of the alpha, with the anulospiral ending’s reflex arc silenced as long as the two are synchronized—that is, as long as the alpha movements correspond to “expected” limits that are successfully mimicked by gamma movements. A movement may be initiated by the gamma motor system as well. In this case, the command signals are organized in the terminal gamma ganglia in the brain stem (the gamma system’s counterpart for the alpha’s cerebral cortex). These signals are then sent through a complicated path known as the gamma loop: They descend through gamma motor neurons out to the intrafusal fibers. These small spindle cells are not strong enough to move a limb, but they are strong enough to stretch their own anulospiral receptors. This stretch automatically fires the spinal reflex arcs connected with the receptors, and the larger alpha motor cells are immediately stimulated to match the contractions of the gamma fibers. As soon as the desired muscle length has been reached, the commands from the brain stem cease, and the spindles hold their new resting length. When the alpha fibers catch up to this new resting length (a matter of a fraction of a second), the anulospiral element is quieted, and contraction ceases.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“These direct internuncial circuits in the spinal cord and this brainstem-directed gamma motor system create an astonishing condition in the numerous and elaborate sensory feedback loops of the spindles and the Golgis: We are consciously aware of almost none of their constant activities. Signals transmitted to the central nervous system from these two receptors operate entirely at a subconsious level, causing no sensory perception at all. Instead, they transmit tremendous amounts of information from the muscles and the tendons to 1) the motor control systems in the spinal cord [and the brain stem], and 2) the motor control systems of the cerebellum.”
― 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

“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

“But the action of the tendon organ’s synapse onto its corresponding motor neuron is not the same as that of the spindle; it is its complimentary opposite, The action of the anulospiral receptor upon its motor nerve is excitatory: When the spindle is suddenly stretched beyond a pre-determined “normal” resting length—as in the knee jerk reflex test—it excites the alpha motor nerve so that a contraction immediately follows which quickly re-establishes the desired “normal” resting length. 7-14: A Golgi reflex arc. In the spinal cord, its effect upon the alpha motor neurons is the opposite of that of the spindles: The Golgi afferent impulse inhibits the muscle fibers associated with it, and excites antagonists. The two kinds of arcs form complementary reflex devices. The tendon organ, on the other hand, has an inhibitory effect upon its alpha motor nerve: When the tension developed upon a tendon exceeds a pre-set “normal” limit, the Golgi inhibits the motor nerve, reducing its level of stimulatory firing and thus relaxing the tension back down to its “normal” resting value. The simplest and most basic function of this inhibitory reflex arc is to prevent the contractile power of the muscles from damaging the tendons and the bones. Many of our muscles are capable of generating enough pull to rip themselves loose from their own moorings, and even the smaller ones which do not have such brute power are in danger of being torn by the uncontrolled pulling of the larger muscles around them. When the Golgi organ senses, due to the increasing tensional distortion of the tendon’s fibers, that a strain or a tear is imminent, its signal becomes powerful enough to inhibit the alpha motor neurons that are stimulating the contraction. Tension is reduced instantly, and the damage is avoided.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“As a team, then, the Golgis and the spindles produce a sensory impression that is very different in kind than the impressions of color, texture, odor, or sound produced by our more conscious sense. Instead of measuring any of these surface qualities, the muscle and tendon organs assess the pure mass of an object. Now mass is an invisible thing. We have only to contemplate the surprises offered by a tennis ball filled with lead, or a large “rock” made of styrofoam in a movie studio, to remind ourselves how easily deceived our other sense organs can be with regard to mass. Mass has nothing to do with surface qualities; it is the measure of an object’s resistance to movement, and I can have no idea of its value until I am actively engaged in moving the object. Nor are the sensory cues relating to mass at all constant with regard to the object. They vary continually, as a function of inertia, according to the speed with which I move the object, or the relative suddenness with which I attempt to change the direction of movement or stop the object. A five pound bucket “feels” much heavier if I swing it rapidly in a circle over my head—that is, I have to brace myself much more forcefully in order to resist its pull. It is the precise value of this resistance which is measured by the Golgi tendon organs, and when their information is correlated with the spindles’ measurement of the exact speed and distance of movement, I can arrive at an accurate estimate of mass, that invisible yet crucial property of all matter.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“There are many variable factors which help to determine just how much work a muscle is doing as it is contracting, and information coming only from the muscle spindles can be as confusing as it is helpful with regard to measuring this real work. For instance, a muscle cell is “weaker” when it is stretched out to its full length, because the myosin and actin chains do not overlap very much and therefore have fewer cross-bridges to ratchet; hence contractions at this end of the muscles range do not have as much force behind them as they do when the muscle shortens by about half and the myosin and actin filaments are overlapping deeply and creating many cross-bridges. Or, increasing fatigue can make a muscle feel as though it is working harder and harder, in spite of the fact that it is actually contracting with less and less force. Even changes in my mood can significantly alter my sense of ease or effort during any given contraction. So the Golgis add an indispensable quantum of information to the spindles’ measure of changing muscle lengths: The Golgis assess the exact amount of resistance which is overcome in order to contract a given distance in a given time.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“As a sensory device, the tendon organ is a close partner to the muscle spindle in the assessment of the specific activity of every one of my alpha motor units. The anulospiral element of the spindle measures the length of a muscle’s fibers, and the speed with which that length is changing. Adding to this information, the Golgi tendon organs measure the tensions that are developed as a result of these changing lengths. The degree of distortion in the parallel zig-zag collagen bundles is a precise gauge of the force with which a muscle is actually pulling on the bone to which it is attached. Such a gauge is really necessary in order to fully and accurately assess the net amount of work force actually being delivered by a muscle, as opposed to merely knowing now much and how fast it is lengthening or shortening. I can shorten my bicep exactly the same distance at exactly the same speed, whether there is a book in my hand or not, and my spindles will register identical information in either case. It is only the differing stress placed upon the tendon organ during the gesture which announces and evaluates the added weight of the book.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“And as with the sensory elements of the motor spindles, the pathways carrying the sensory information from the Golgis are culminated in the ganglia of the brain stem, with very few direct connections to the conscious cortical areas. We normally receive no more conscious sensation from the Golgis than we do from the muscle spindles; their information is processed and responded to primarily in the brain stem and the spinal cord, beneath our level of conscious awareness.”
― Deane Juhan, Job's Body: A Handbook for Bodywork

“The Golgi organs themselves are multi-branched type endings of sensory axons, which are woven among the collagen fibers near the muscle cells, and which are stimulated by the straightening and recoiling of the tendon. As is the case with the muscle spindles, the stimulation of a single tendon organ is highly specific: Each particular organ is most directly affected by the lengthening and contracting of the few alpha muscle fibers which attach to the collagen bundles containing that tendon organ, so that each Golgi is responsive to the activities of only ten to fifteen alpha motor units.”
― 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