What reflexes are there on the leg?
Four reflexes are also normally tested on the leg.
- Patellar tendon reflex: the examiner taps on the tendon, which can be reached slightly below the patella, when the legs are slightly elevated. This stretches the leg in the knee joint.
- Adductor reflex: is triggered by tapping the leg on the inside just above the knee.
This causes the legs to close.
- Tibialis- Posterior Reflex: to trigger the reflex, a tendon is tapped just above the inner ankle, causing the foot to rotate inward.
- Achilles tendon reflex: here the foot is stretched slightly and struck on the Achilles tendon at the rear lower end of the lower leg or on the ball of the foot. This causes the foot to fold down.
The patellar tendon reflex, which is also abbreviated PSR, is a monosynaptic muscle reflex. This means that the reflex arc runs over only one synapse, which connects the two nerve cells, also called neurons.
It is triggered by a blow to the tendon of the quadriceps femoris muscle, the quadriceps extensor of the thigh muscles, and thus leads to a contraction of the quadriceps femoris muscle and therefore to an extension in the knee joint. Receptor and effector organ of the patellar tendon reflex are therefore identical. The patellar tendon reflex is mediated via the femoral nerve.
The sensitive neurons (afferences) transmit the stimulus to the spinal cord segment L2-L4.There the excitation is switched to the motor nerve fibers (efferences) and runs back to the muscle fiber in the femoral nerve, where a contraction is triggered. The reflex can be triggered and examined by the doctor with a reflex hammer as part of a neurological examination. If the desired reflex response does not occur, this may indicate damage to the spinal cord segment L2-4, for example in the form of a herniated disc or injury to the femoral nerve, and should be further investigated.
