Issue link: https://www.massageandbodyworkdigital.com/i/72121
The vastus intermedius is located just beneath the rectus femoris, and between the vastus lateralis and vastus medialis. This muscle cannot be seen without removing the rectus femoris. It is partly attached to the vastus medialis, and the two work in unison during extension of the knee. The vastus medialis lies deep to the rectus femoris on the medial side of the thigh, and it originates on the body of the femur, attaching distally to the medial aspect of the patellar tendon. The primary function of this muscle is to straighten the knee during the final five degrees of extension. Atrophy of this muscle usually occurs when the person has experienced an injury that causes pain upon full- knee extension. For example, a torn meniscus in the knee often makes it impossible to fully straighten the knee; therefore, this muscle usually atrophies after a few months from lack of use. The fourth quadriceps section, the vastus lateralis, is on the lateral side of the vastus intermedius and covers most of the lateral thigh. The lateralis is the largest and strongest part of the quadriceps group. It has multiple attachments to the greater trochanter, gluteal tuberosity, linea aspera, gluteus maximus, and biceps femoris, among others, which makes it structurally strong and less vulnerable to injury. All four quadriceps muscles work in concert to extend the knee, and they are prime movers in walking, running, jumping, and squatting. WHY DOES INJURY OCCUR? Any quadriceps injury is a real nemesis for athletes, dancers, or hikers. Injury frequently occurs when the thigh muscles begin to fatigue and the stress on the thigh increases. This often happens near the end of a run, intense athletic match, race, or walk, or when leaning backward while kneeling on both knees (as might occur in yoga or dance class). The site of injury can be anywhere from the top of the thigh where the rectus femoris tendon attaches to the AIIS, or anywhere along the muscle belly. If the pain is present at the front of the hip, it could be the hip joint, or the sartorius tendon, that is injured. If pain is lower down in the anterior thigh, injury could be in the muscles themselves, or it could be a referred pain from the low back. The muscle-tendon unit that is most commonly injured is the rectus femoris. This muscle is the longest and weakest muscle of the four that comprise the quadriceps—it is the one that helps you lift the thigh to flex at the hip, as well as extend the knee. The other three quadriceps muscles primarily help you straighten the knee. If you see someone limping because of pain, it is usually because of an injury to the rectus femoris tendon or an inflammation in the hip joint. Damage to the rectus femoris tendon is one of the injuries that results from incorrect stretching of the front thighs. When we stretch, we want to elongate the muscle fibers. We do not want to stretch the tendons, which weakens the fibers and makes them more vulnerable to injuries. Because Rectus femoris Vastus lateralis Vastus medialis Sobotta: Atlas der Anatomie des Menschen @ Elsevier GmbH, Urban & Fischer Verlag Munich. Celebrate ABMP's 25th anniversary and you may win a refund on your membership. ABMP.com. 107