The so-called quadriceps femoris muscle is located on the ventral side (front or ventral side) of the thigh and consists of four different muscle heads. Therefore, it is more colloquially known as the four-headed thigh extensor, the four-headed thigh muscle, or the quadriceps.
What is the quadriceps femoris muscle?
The quadriceps femoris muscle is the anterior skeletal muscle of the thigh. Because it consists of four different parts (called muscle heads), it is often called somewhat more colloquially four-headed thigh muscle, four-headed thigh extensor or else quadriceps. It is on average more than 150 cm² wide and is therefore one of the strongest muscles of the human body. Due to its width, it significantly shapes the lateral contours and the front of the thigh and gives them their form. If the quadriceps is affected in its function, this can have a significant impact on the overall movement function when running and standing.
Anatomy and structure
The quadriceps is made up of four distinct parts, called muscle heads in medical terminology. These four individual muscle parts are titled the straight thigh muscle (also called the rectus femoris muscle), the mid broad muscle (vastus medialis muscle), the mid broad muscle (also called the vastus intermedius muscle), and the outer broad muscle (vastus lateralis muscle). Each individual muscle head has its own tasks and functions that ultimately affect the overall function of the quadriceps femoris muscle. The rectus femoris muscle originates both at the anterior bony prominence of the pelvis (spina iliaca anterior inferior) and at the superior border of the pelvic socket (medically called the acetabulum). The fibers terminate in the common attachment tendon, the quadriceps tendon. The vastus medialis muscle divides into two parts. One part spirals from the longitudinal bony ridge of the femur (linea aspera), across the anterior bony side (linea intertrochanterica) of the femur bone, and around the bony shaft until it finally merges with the quadriceps tendon. The second part bypasses the patella toward the body and attaches to the medial articular process (condyle medialis) of the tibia via the retaining ligament of the patella (retinaculum patellae mediale). The vastus lateralis muscle originates at the linea aspera, winds around the bony shaft of the femur, and largely merges with the quadriceps tendon. The vastus intermedius muscle, on the other hand, begins at the front of the femur and ends in the attachment tendon.
Function and Tasks
The quadriceps is also called the four-headed thigh extensor because it is the only extensor muscle of the knee joint. For this reason, it plays a crucial role in almost all movements that require the legs. Extension of the knee is necessary when walking or getting up from a sitting or lying position, but also when climbing stairs. In addition to this, the quadriceps femoris muscle prevents the knee joint from buckling when standing or walking. It also strengthens and supports the hip joint and has a significant effect on the rotation of the knee joint. This means that it also influences movements that take place in the lower part of the legs. Thus, if the quadriceps are injured or impaired, there will be severe disruptions to the range of motion. In a minor form, these can lead to difficulty walking or standing. However, in the case of a severe failure of the quadriceps femoris muscle, it can also happen that the leg completely buckles at the knee joint and the affected person is unable to load it successfully. In other cases, the quadriceps femoris muscle contracts uncontrollably, which also leads to disturbed movements. In addition to the functions required for movement, however, the quadriceps femoris muscle also has a protective function: When the knee is extended, the quadriceps prevents surrounding tendons, nerves and tissues from being pinched between the kneecap and the femur by targeting the right parts of the muscle.
Diseases and ailments
The four-headed thigh muscle can be disrupted in its function by both external influences and diseases of the body (such as the intervertebral discs).Typical injuries of the quadriceps are strains of the individual muscle heads, which can occur, for example, due to overloading during sports or accidents. These usually manifest themselves in pain that restricts mobility. Depending on the severity and type of injury, the discomfort and restrictions can last several days to weeks. However, the quadriceps is also disturbed in its function by herniated discs or by strokes in which the L3 and L4 nerve roots or the patellar tendon reflex (PSR) have been impaired or cancelled. In this case, there is less pain than numbness and paralysis. As a result, the quadriceps slackens or contracts only uncontrollably, so that the execution of the movements controlled by it is no longer possible or only with great difficulty. The rectus femoris muscle is one of the shortest muscles in the body. For this reason, it is the most prone of all human muscles to injury – which ultimately affects the entire four-headed thigh muscle. This is because when the rectus femoris muscle shortens over time, it affects the entire length of the quadriceps as well. Progressive shortening of the quadriceps femoris muscle can be counteracted by regular stretching exercises that involve slowly and gently pulling the foot toward the buttocks over and over again.
