Replacement results from one or more muscles trying to compensate for a lack of strength in another muscle or group of muscles. Replacement is a good indication that the muscle being tested is weak, which is adequate fixation has not been applied, or that the subject has not received adequate instructions on how to perform proof. The muscles that normally work together in the movements can act as replacements. These include fixation muscles, agonists and antagonists. The replacement with the fixing muscles occurs specifically in relation to the movements of the shoulder and hip joint. The muscles that move the shoulder blade may produce secondary arm movement; The muscles that move the pelvis can produce a secondary movement of the thigh. These replacement movements look similar to shoulder or hip joint movements, but they are not. The close relationship of the muscles determines their replacement, assistance and stabilization action during individual muscle testing. True abduction of the hip joint is achieved by the hip abductors with normal fixation of the lateral trunk muscles. When the hip abductors are weak, apparent abduction from the replacement action of the lateral trunk muscles may occur. The pelvis is raised to the side, the leg is lifted off the table, but there is no real abduction of the hip joint. happens. The antagonists can produce movements similar to those of the test. If the finger flexors are weak, the action of the Wrist extensors can cause passive flexion of the fingers from stress applied to the flexor tendons. The substitution with other agonists determines a movement of the part in the direction of the stronger agonist or a displacement of the body in order to favor the attraction of that agonist. For example, during the gluteus medius test in lateral decubitus, the thigh will tend to flex if the fascia lata tensor tries to replace the gluteus medius, or the trunk may rotate backwards so that the fascia lata tensor can maintain a position which appears to be the desired test position. For accurate muscle exams, no substitutions should be allowed. The position or movement described as test must be performed without moving the body or rotating the piece. These secondary movements allow other muscles to replace the weak or paralyzed muscle. An experienced examiner, aware of the ease with which normal muscles perform the tests, will easily detect replacements. When using the rehearsal position in place of the rehearsal movement, even an inexperienced examiner can detect the sudden change in the body or part that results from straining to compensate for muscle weakness.

Weakness, shortening and contracture

Included with the descriptions of the muscles in this text is a discussion of the loss of movement or position. deformity resulting from muscle weakness or muscle shortening. Weakness is used as a general term that covers a range of strength from zero to fair in the non-weight-bearing muscles, but also includes fair in the weight-bearing muscles. Weakness will result in loss of motion if the muscle cannot contract enough to move the part through the full or partial range of motion. A contracture or shortening will cause loss of motion if the muscle cannot be stretched throughout its range of motion. Contracture refers to a degree of shortening that results in a marked loss of range of motion. Brevity refers to a degree of brevity that results in a mild to moderate loss of range of motion. There is usually no fixed deformity due to weakness, unless contractures develop in stronger opponents. In the wrist, for example, a fixed deformity will not develop due to wrist extensor weakness unless the opposing flexors maintain the wrist flexion position. There is a state of muscle imbalance when a muscle is weak and its antagonist is strong. The stronger of the two opponents tends to shorten and the weaker of the two tends to stretch. Both weakness and shortening can cause misalignment. Weakness allows for a deformity position, but brevity creates a deformity position. In some parts of the body, positions of deformityit can develop due to weakness even if the opposing muscles do not contract. Gravity body weight exerts opposite forces. An upper back kyphotic position may be due to weakness in the upper back muscles, regardless of whether the anterior torso muscles are contracting. A pronation position of The foot can exist if the inverters are weak because the weight of the body when standing distorts bone alignment. If the opposing peroneal muscles contract, a fixed deformity will result. The word narrow has two meanings. It can be used interchangeably with the short term, or it can be used to mean tight, in which case it can be applied to a short or stretched muscle. The short, tight hamstrings will feel tense on palpation. The hamstrings that are tense and tense will also feel tense. From the point of view of the treatment prescription, it is very important to recognize the difference between stretched and shortened muscles. Additionally, some muscles are short and remain in what appears to be a semi-contracted state. On palpation, they feel firm or even stiff without being tense. For example, the muscles in the back of the neck and upper trapezius are often strained in people with poor posture in the upper back, head, and shoulders.

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