Final answer:
The term 'CR knee' in the context of a reflex arc refers to the knee's role in initiating a reflexive action that is part of a simple spinal reflex used to assess neurological function.
Step-by-step explanation:
The term 'CR knee' refers to the knee's involvement in a reflex arc, which is a neural pathway that mediates a reflex action. In a reflex arc involving the knee, such as when a doctor uses a reflex hammer to tap the patellar tendon, a nerve impulse is generated. This stimulus travels from the knee to the spinal cord. Once it reaches the spinal cord, a message is sent back to the muscles of the leg, causing a kicking motion. This process occurs without the need for conscious thought and is an example of a simple spinal reflex that doctors use to assess the nervous system function.