Net internal torque accounts for the combined effect of which groups?

Net internal torque accounts for the combined effect of which groups?

• A. Only gravity and friction
• B. Only one isolated agonist
• C. Only passive ligaments
• D. Agonist and antagonist muscle groups

Answer: (D)

Net internal torque reflects the sum of the forces that muscles crossing the joint produce to rotate it. The muscles come in two primary roles: agonists, which generate the torque needed to move the joint in a chosen direction, and antagonists, which produce torque in the opposite direction to control, slow, or stabilize the movement. When you consider what's happening inside the joint, the overall rotational effect is the combination of both groups’ torques. External factors like gravity or friction act on the limb from outside the joint and aren’t part of the internal torque balance, so they’re not counted among internal torques. Co-contraction of agonists and antagonists is a common way the body stabilizes joints, further illustrating that the net internal torque arises from the combined action of these muscle groups.

Net internal torque reflects the sum of the forces that muscles crossing the joint produce to rotate it. The muscles come in two primary roles: agonists, which generate the torque needed to move the joint in a chosen direction, and antagonists, which produce torque in the opposite direction to control, slow, or stabilize the movement. When you consider what's happening inside the joint, the overall rotational effect is the combination of both groups’ torques. External factors like gravity or friction act on the limb from outside the joint and aren’t part of the internal torque balance, so they’re not counted among internal torques. Co-contraction of agonists and antagonists is a common way the body stabilizes joints, further illustrating that the net internal torque arises from the combined action of these muscle groups.