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Antagonist muscles are simply the muscles that produce an opposing joint torque to the agonist muscles. [9] This torque can aid in controlling a motion. The opposing torque can slow movement down - especially in the case of a ballistic movement. For example, during a very rapid (ballistic) discrete movement of the elbow, such as throwing a dart ...
Schematic representation of patellar tendon reflex (knee jerk) pathway. The patellar reflex, also called the knee reflex or knee-jerk, is a stretch reflex which tests the L2, L3, and L4 segments of the spinal cord. Many animals, most significantly humans, have been seen to have the patellar reflex, including dogs, cats, horses, and other ...
A muscle synergy is composed of agonist and synergistic muscles. An agonist muscle is a muscle that contracts individually, and it can cause a cascade of motion in neighboring muscles. Synergistic muscles aid the agonist muscles in motor control tasks, but they act against excess motion that the agonists may create.
The sensory input from the quadriceps also activates local interneurons that release the inhibitory neurotransmitter glycine onto motor neurons of antagonist muscles, blocking their stimulation (in this case the hamstring muscles). The relaxation of the opposing muscle facilitates (by not opposing) the extension of the lower leg.
Electrical activity is only present in the muscle when the muscle voluntarily contracts. [9] When the muscle is contracted, the EMG is able to display the force of the contraction or how the nerves can respond to stimulation. [10] An EMG of coactivation would display the agonist and antagonist muscle contracting simultaneously.
The vastus lateralis (/ ˈ v æ s t ə s ˌ l æ t ə ˈ r eɪ l ɪ s, ˈ r æ-/), also called the vastus externus, [1] is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh. Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward.
Knee pain is thought to be primarily associated with specific quadriceps muscle weakness or fatigue, especially in the vastus medialis obliquus (VMO).It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibers to the generation of an inadequate motor command in the motor cortex. [4]
At the same time, signals travel up the spinal cord and cause contraction of the contralateral muscles of the hip and abdomen to shift the body’s center of gravity over the extended leg. To a large extent, the coordination of all these muscles and maintenance of equilibrium is mediated by the cerebellum and cerebral cortex. [5]