Localization of the most frequent herniated discs of the lumbar spine
L3 and L4 describes the height of the prolapse and is a very common location for a prolapse of the intervertebral disc. The herniated disc is located at the level of the lumbar spine, in fact at the same level as the uppermost point of the iliac crests. Due to natural signs of wear and tear, the area between the fourth and fifth lumbar vertebrae (“L4 and L5”) is the most common location for a herniated disc.
The reason for this is that this area of the lumbar spine is subjected to the most strain during physical exertion or sports. The herniated disc L4/5 presses on the nerve that leaves the spinal cord in this area. This causes severe pain in the outer front thigh and the inner front of the lower leg.
The pain is often triggered by unusual movements or when lifting heavy loads and can be intensified by sneezing or coughing. In addition, there may also be sensory disturbances in the described areas of the leg, for example tingling, numbness or a furry feeling, similar to a leg that has fallen asleep. The so-called identifying muscle for a slipped disc L4/L5 is the muscle quadriceps femoris, the four-headed thigh extensor on the front of the thigh.
If the herniated disc presses on the motor nerve fibres to this muscle, the knee joint can no longer be stretched. On the basis of the identification muscle, often only the examination of the knee extensors can already provide a reasonable suspicion for the diagnosis of a herniated disc in the area L4/5. Even lifting the toes is only possible to a limited extent, which is why it is difficult or impossible for the affected person to walk on the heels while the toes are stretched in the air (heel gait).
A herniated disc L5/S1 lies between the fifth lumbar vertebra and the first coccyx vertebra. Often a herniated disc in this area is simply called “sciatica“, because the sciatic nerve causes severe pain when it is constricted by the herniated disc. Checking the so-called Lasègue’s sign is a simple method to make a suspected diagnosis of a narrowing of the sciatic nerve.
The affected person lies on his back and the painful leg is lifted while the knee joint is stretched. This stretches the nerve and causes pain in case of a constriction. The pain from a herniated disc in the area of L5/S1 can radiate to the heel and little toe.
In these areas, the leg may experience sensory disturbances, such as tingling, numbness or a furry feeling. The so-called identifying muscle for a herniated disc L5/S1 is the muscle triceps surae, the three-headed calf muscle on the back of the lower leg. If the herniated disc presses on the motor nerve fibres to this muscle, the foot can no longer be bent (angled downwards). On the basis of the characteristic muscle, it is often only by examining the active and powerful foot flexion that the justified suspicion of a herniated disc in the area L5/S1 can already be diagnosed, since the affected person can no longer walk on the toes or can only walk with difficulty.
