When a physician elicits the knee-jerk reflex by tapping deep tendons in the knee, the normal response is for the lower leg to swing forward. When this happens:
Correct answer: A. Muscles in the front of the thigh are contracting and muscles in the back of the thigh are relaxing
- A. Muscles in the front of the thigh are contracting and muscles in the back of the thigh are relaxing
- B. Muscles in the front of the lower leg are contracting and muscles in the back of the lower leg are relaxing
- C. Muscles in the back of the thigh are contracting and muscles in the front of the thigh are relaxing
- D. Muscles in the back of the lower leg are contracting and muscles in the front of the lower leg are relaxing
- E. None of the above
Explanation
In the Knee-Jerk reflex, the leg moves in forward direction (as shown below). For this leg movement, the muscles in front of the thigh contract, and muscles at the back of the thigh relax.
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About Support and Movement
Support and movement covers the axial and appendicular skeleton, bone structure, joints and the arrangement of skeletal muscles. Muscle contraction is explained through actin, myosin, sliding filaments, calcium ions and ATP, while arthritis is distinguished as a disorder of joints rather than a normal part of movement.
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