PRINCIPLES OF MANUAL MEDICINE THIRD EDITION BY PHILIP E. GREENMAN

neural system is more to the lateral aspect of the Chapter 7 9 Lower Extremity Technique 489 knee. system. Lower extremity joint function is essential for 4. Operator increases the tension by adducting and in­ symmetric gait. The sole of the foot is a sense organ ternally rotating the extended leg (Fig. 19.88). for sensory motor balance. Evaluation and restoration of function to the foot and lower extremity are essen­ 5. Operator can use dorsiflexion of the foot on the tial components of the treatment of patients with mus­ ankle for additional neural and dural tension culoskeletal problems. (Fig. 19.89). SUGGESTED READINGS 6. When using these maneuvers for dural and neural mobilizations, it is imperative to use an on and off of Butler DS. Mobilization ofthe nervous system. Melbourne: the tension at the restrictive barrier. Do not use a Churchill Livingstone, 1 99 1 . sustained application of force. Kaltenborn FM. Manuelle Therapie d er Extremitatenge­ CONCLUSION lenke. Oslo: Norlis Bokhandel, 1 976. The foot of the lower extremity is the bottom block of Mennen ] McM. Foot pain. Boston: Little, Brown and the postural structural model. Intrinsic dysfunction Company, 1 964. within the foot or dysfunction secondary to other dys­ functions within the lower extremity can influence the Mennen ] McM. Joint pain. Boston: Little, Brown and biomechanical function of the total musculoskeletal Company, 1 9 64. Mennen ] McM. The musculoskeletal system: difef rential diagnosis from symptoms and physical signs. Gaithers­ burg, MD: Aspen Publishers, 1 992. Figure 19.88. Figure 19.89.

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Section CLINICAL INTEGRATION AND CORRELATION

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EXERCISE PRINCIPLES AND PRESCRIPTIONS Exercise has a long history in the healing arts. Exer­ designed for the maintenance of aerobic capacity and cise has been used for the maintenance of general restoration of fitness after bouts of injury or disease. health and for the prevention of disease by both East­ ern and Western cultures. The ancient Greeks origi­ Despite all of the activities described, it has been nated the Olympic movement to honor those with ex­ this author's observation that many health profession­ ceptional athletic skills. Modern Olympians continue als, in a variety of disciplines, have limited knowledge that tradition, spending enormous time and energy and understanding of how to prescribe exercises that enhancing their level of expertise and maximizing are appropriate for their patients. While there are a their performance potential. number of programs that have generic value, each pa­ tient is an individual and requires an exercise pro­ Today there is an ever-increasing interest in ex­ gram specific for his or her problem. The practitioner ercise and sporting activities. There continues to be needs the skill to identify problems of the patient's an increase in the numbers of health spas, athletic neuromusculoskeletal system and to prescribe appro­ centers, and clubs dedicated to the principle that ex­ priate exercises just as they prescribe appropriate ercise is a fundamental good that is not only essential medication, manual medicine, or surgical interven­ for one's health but is also an enjoyable leisure past tion. The following principles and procedures are time. those that this author has found effective and are the results of the contributions of numerous authors and Health professionals of many disciplines, particu­ colleagues. larly physical therapists, have increasingly used exer­ cise. William's flexion exercises and Mackenzie's ex­ PRINCIPLES OF MUSCLE IMBALANCE tension program have been widely used for lower back pain. There is more to William's program than flexion As stated in Chapter 1, the goal of manipulation is to and more to Mackenzie's program than extension, but these systems, and many similar programs, are de­ restore maximal, pain-free movement of the muscu­ signed to enhance the strength and flexibility in the loskeletal system in postural balance. When the ma­ patient who suffers from lower back pain from a vari­ nipulative intervention has achieved maximum mobil­ ety of causes. In the management of lower back pain, ity, the question remains, how is it maintained? The a great emphasis has been placed on the principle of obvious answer is an appropriate exercise program core stability. Recent work from Australia has demon­ the patient can perform that maintains the functional strated the significant role of the transversus abdomi­ capacity of the musculoskeletal system within the con­ nus muscle contraction in core stability. straints of the available anatomy. The manual medi­ cine practitioner is limited by the available anatomy, There are many texts on procedures for manual which may be altered by genetic development, single muscle testing, stretching, and strengthening. More or repetitive trauma, and surgical intervention. De­ recently, video series on the topic have been devel­ spite the altered anatomy and pathology present, it is oped, for health professionals and laypersons, to assist surprising and satisfying to both the practitioner and in the maintenance of health and as part of therapeu­ the patient to see the amount of functional capacity tic treatment plan. that can be restored and maintained by an appropri­ ate exercise program. Numerous diagnostic and therapeutic exercise equipment systems have been developed and are cur­ pAn appropriate exercise prescription rovides the rently on the market. This equipment objectively measures range of motion and muscle strength in var­ patient with the ability, and responsibility, to maintain ious physical activities. Some machines have been de­ a high level of neuromusculoskeletal health. It is im­ veloped to exercise specific areas of the body and re­ portant that the patient understands and commits to lated muscle groups, whereas other equipment IS perform the necessary exercise program. While being as comprehensive as necessary, it should be simple 493

494 Principles of Manual Medicine sition of joints and the rate of change in relationship. This articular information, combining impulses from and be performed without depending on specialized muscle spindles and Golgi tendon organs, reporting equipment or facilities. Obviously, if appropriate on muscle length and tension, is transmitted to the equipment is available, its use can be beneficial. Of ut­ spinal cord for central processing. Afferent fibers most importance is that patients understand that fol­ from nociceptors and mechanoreceptors enter the lowing a disabling musculoskeletal condition, it is im­ dorsal horn where numerous neuronal reflexes are perative to continue an active exercise program for initiated and mediated. the rest of their lives. Neurons PRINCIPLES OF MOTOR CONTROL There are numerous combinations of neuronal con­ Muscle Pathology nections acting on the motor neuron of the final com­ mon pathway. Divergence describes the process of a Functional pathology of muscle results from a per­ single neuron synapsing with several target end or­ turbation of a highly complex neurologic control sys­ gans, either directly or through interneurons. Conver­ tem. A disturbance of musculoskeletal function initi­ gence describes the process where a motor neuron re­ ates a series of events beginning with stimulation to ceives and summates inputs from a variety of fibers, mechanoreceptors and nociceptors resulting in affer­ including afferents, interneurons, and descending ent neural activity initiating a variety of reflexes at the fibers from other spinal and supraspinal regions. Gat­ cord, brainstem, and cortical levels. The final com­ ing is the process of altering the output from the mo­ mon pathway is the alpha motor neuron that stimu­ tor neuron via inhibitory interneurons or inhibiting lates the muscle fiber to contract, and through the neurons from descending control signals. Occasion­ gamma system, the muscle spindle to adapt, resulting ally, the gate can be initiated by presynaptic inhibi­ in alteration in muscle tone. Chronic articular or a tion, an example is the descending inhibitory control muscle dysfunction feeds the afferent loop with more signals acting on the presynaptic terminals of afferent nociception and abnormal mechanoreceptor infor­ fibers. mation, perpetuating ongoing aberrant muscle tone. Interruption and reprogramming of this vicious cycle Four Components of the Motor System contribute to improvement of overall muscle tone and maintenance of balance. There are four hierarchically organized components of the motor system. From above downward they in­ Morphology clude the premotor cortical regions, the motor cor­ tex, the brainstem, and the spinal cord. It is through The work of Wyke and colleagues has led to an in­ the spinal cord that many activities of the motor sys­ creased appreciation of the morphology and func­ tem are initiated and maintained. The cord is pro­ tional characteristics of articular receptor systems. grammed to respond to peripheral and central stim­ ulations. The spinal cord has the capacity to learn. Receptors Preprogrammed normal behavior can be replaced by abnormal response if the cord has repetitive aber­ There are four different types of receptors (Table. rant stimulation. This process can be viewed as both good and bad, because the cord that learns to per­ 20.1). These receptors are found injoint capsules, lig­ petuate abnormal mechanical behavior through per­ sistence of structural and functional pathology can aments, and articular fat pads. They have different be reprogrammed to activity that is more normal sizes, shapes, clusters, and nerve fibers that range through appropriate manual medicine and exercise from small unmyelinated fibers to very small, small, procedures. medium, and large myelinated fibers. Their different behaviors include responses to static and dynamic All four components of the motor system are func­ change, with low or high thresholds, and range from tionally interrelated. A stimulus from the periphery rapidly adapting to slow adapting to nonadapting. In initiates afferent input to segmental spinal reflexes simplistic terms, this system provides the central nerv­ and carries information centrally to the brainstem and ous system information on the three-dimensional po- cortical areas. The cord level information proceeds through efferent spinal pathways to muscle groups re­ Table 20.1. sulting in force generation to displace a load. Re­ Four Types of Articular Receptors sponse to this activity returns by afferent loops,joining with the original afferent stimulation, to continue in­ Shape Nerve Characteristic formation processing at the cord level. The initial af­ I. Globular Small myelinated Static and dynamic mechanoreceptors ferent input stimulates cortical and brainstem levels 2. Conical Large myelinated 3. Fusiform Medium myelinated Dynamic mechanoreceptor 4. Plexus Unmyelinated Mechanoreceptor Nociceptor

Chapter 20 Exercise Principles and Prescriptions 495 thus initiating descending pathways from the brain­ rapid stimulation to the spindle to shorten in response stem and the motor cortex. These complex descend­ to the shortening of the extrafusal fibers. The spindle ing pathways are modulated through the basal gan­ has both nuclear bag and nuclear chain fibers, each glion and cerebellar systems thereby changing having their own afef rent control. The spindle re­ brainstem activity, which descends through the cord, sponds to change in static length as well as dynamically modulates cord reflexes, and ultimately influences in the rate of change of length. Control of muscle ten­ muscle activity. sion is primarily mediated through the Golgi tendon apparatus. While the muscle spindles are parallel to the spinal Corel. The spinal cord has intricate neu­ extrafusal fibers, the Golgi tendon organs are in series. The Golgi tendon organ responds to muscle stretch ronal interconnections through long and short pro­ and contraction. It discharges most actively during priospinal pathways that influence motor neuron muscle contraction and initiates an inhibitory reflex pools to the muscles of the axial skeleton and the ex­ arc preventing overload of the muscle and the muscu­ tremities.· The neuronal pools for the axial muscles lotendinous junction. are oriented medially, those for the extremities more laterally, with the proximal limb being central and the The alpha motor neuron is controlled by central distal limb more lateral. These neuronal pathways are demand and through feedback loops. The central con­ both ipsilateral and contralateral and course up and trol of the gamma motor neuron establishes the length down through several levels of the spinal cord. of the muscle spindle and sets the anticipated activity of the positive stimulation to the alpha motor neuron. Brainstem Pathways. There are two groups of de­ Mter the alpha motor neuron is stimulated, changes in scending brainstem pathways. The first is the ventral muscle length and tension occur. The spindle com­ medial group, which includes the reticulospinal, the pares the response to the anticipated activity. Feedback vestibulospinal, and the tectospinal tracts. The dorso­ loops to the spinal cord modulate the continued cen­ lateral pathways are primarily those related to the red tral control of the alpha motor neuron. Differences be­ nucleus. The rubrospinal tract crosses centrally and tween anticipated and actual change result in appro­ descends in the contralateral dorsolateral funiculus of priate muscle length and tension through the activity. the cord. These descending pathways provide much of Feedback loops from the spindle report difference in the information for central control of cord and spinal length, while the Golgi tendon organ reports differ­ column activity. ence in force. Feedback loops can be either excitatory or inhibitory to the alpha motor neuron so that the fi­ Cortical Pathways. The descending cortical path­ nal action of muscle is appropriate. ways include the crossed and uncrossed systems. The lateral cortical spinal tract crosses in the pyramidal Another Reflex Pathway desiccation and terminates in the lateral aspect of the cord. This system has considerable input to the Another basic reflex pathway governs reciprocal in­ rubrospinal tracts of the brainstem. The ventral corti­ nervation and inhibition. Stimulation to both limb cal spinal tract is uncrossed and terminates more cen­ flexor and extensor muscles is called cocontraction trally in the ventral portion of the cord. Influence and stabilizes a joint and restricts its movement. Dur­ from this tract occurs through the ventral medial ing joint flexion, the flexor contracts, and by recip­ brainstem pathways. Most cortical influence on cord rocal inhibition, the extensor muscle group relaxes, activity occurs through the brainstem pathways rather allowing controlled flexion activity. The reverse is than directly at cord level. The information descend­ true for extension: The extensor contracts and the ing from the cortex and brainstern is designed to ini­ flexor is inhibited and relaxes. This reciprocal inhi­ tiate muscle action and modulate the action on the ba­ bition occurs contralaterally and ipsilaterally. When sis of response. Much of the descending information the ipsilateral flexor contracts, there is reflex inhibi­ is inhibitory to the programmed cord response so that tion of the contralateral flexor. The harder a muscle the resultant action is controlled, smooth, and appro­ contracts, the more it inhibits its antagonist. This priate for the desired result. phenomenon occurs ipsilaterally and contralaterally. Through this reflex pathway, facilitated muscle con­ Alpha Motor Neuron. Stimulation to the alpha mo­ tracts and is maintained in a shortened position, re­ sulting in inhibition of its antagonist, which becomes tor neuron, the final common pathway, results in mus­ weakened. cle activity. The resultant action is reported through a complex feedback system to determine both muscle Muscle Fiber Type length and muscle tension. Control of muscle length is primarily determined by the response of the muscle Fiber type, either slow or fast twitch, characterizes spindle. When the muscle is stretched, increasing dis­ muscles. Slow-twitch muscle uses oxidative metabo­ charge from the spindle reports to the cord that the lism and has a high capillary density giving it its char- muscle is lengthening. When the muscle contracts with shortening of the extrafusal fibers, there is initial mo­ mentary electrical silence from the spindle, followed by