So for this we have receptors called muscle and tendon spindles that specifically sense stretching.

，我们有称肌肉和腱梭的受体，它们专门感知拉。

When we tap your, let's say your patellar tendon that causes a stretch in a muscle spindle, this sends a signal back to the sensory neuron, which activates a motor neuron in the spinal cord to cause your knee to kick up.

我们敲击你的，比方说你的髌骨腱，它导致肌肉纺锤体的拉，向感觉神经元发送信号，激活脊髓中的运动神经元，使你的膝盖抬起。