Segments of the spinal column
In humans, the sensitive neurons (afferences) move to the lumbar segments (lumbar vertebrae) L2-L4, in smaller animals to L3-L6. There the excitation is switched to the motor neurons (efferences) via one synapse each. These neurons pass through the plexus lumbalis and back to the muscle in the femoral nerve, where a contraction of the quadriceps femoris is triggered.
Failure of the patellar tendon reflex
By testing the patient’s own reflexes as well as sensory and motor functions, injuries in the spinal column can be localized more precisely. This is also the case with the patellar visual reflex. If the patellar tendon reflex weakens or even fails, it can be assumed that there is a nerve injury in the area of L3/L4 or at the level of LWK 2/3 and LWK 3/4.
A very common example of this is the herniated disc of the lumbar spine. Less frequent causes, however, are malignant tumors or a narrowing of the spinal canal (spinal stenosis of the lumbar spine), as well as a cystic mass.
