Reflex of the Quadriceps Thigh Muscle

The quadriceps femoris reflex (r. musculi quadricipitis femoris) is one of the most frequently studied tendon reflexes. It allows you to evaluate the function of the motor neurons of the spinal cord and the nerve pathways innervating the quadriceps femoris muscle.

To study the reflex, the patient is in a sitting position with his leg hanging down. The doctor applies a gentle blow with a hammer to the quadriceps tendon just above the knee joint. This leads to stretching of the muscle and activation of proprioceptors. In response, a reflex contraction of the muscle occurs, causing extension of the lower leg in the knee joint.

The normal response is extension of the lower leg with slight movement of the foot. The absence or weakening of the reflex may indicate damage to the motor neurons of the spinal cord, roots or peripheral nerves. Hyperreflexia is observed with damage to the upper motor tracts. Thus, the study of the reflex from the quadriceps femoris muscle allows one to obtain important information about the state of the central and peripheral nervous system.

The quadriceps femoris reflex is the body's response to stretching or contracting this muscle. It is also called the “jumping reflex”.

This is one of the most important reflexes of the body: thanks to it, a person stands on his feet, he has the ability to crawl, stand up, and take steps. Essentially, these are basic human skills - crawling, walking, the ability to stand up without assistance. And although reflexes do not account for 95% of all problems, their condition has a direct impact on human health. Disruption of its functioning in 50% of cases can lead to chronic diseases.

What is a reflex? If we talk about muscles, then this is a movement that is carried out due to the contraction of muscle fibers. Simply put, muscles contract, reflexively transmitting information to the brain about their condition. Thanks to this circuit, the brain gives commands to the muscles to carry out movements or respond to stimuli. This is how reflex arcs work, located in all parts of the body where there are large ligaments or muscles: in the area of ​​​​the fingers and feet, in the shoulder region, along the spine, in the diaphragm. Jumping reflexes are very important for the development of the musculoskeletal system. The quadriceps fiber has an abdomen, and when it contracts, the hips also contract. This is necessary for crawling and rolling over in an upright position. If there is no response, this is a symptom of damage to the spinal cord or spinothalamic tract of the brain. In such cases, spasmodic muscles reflexively contract and prevent movement. To protect the child’s legs and speed up the time of adaptation to a vertical position, the function of the hips is organized by a reflex mechanism. Thus, neither until the moment the child walks, nor during the first steps, he does not depend on the brain and does not fall. Subsequently, it is important to develop the nervous regulation of the child’s leg muscles, which will form the basis for the formation of gait biomechanics.