Full Vastus Lateralis Muscle Description
[Continued from above] . . . From its origins, the muscle fibers of the vastus lateralis extend anteriorly and distally to merge with the other three muscles of the quadriceps, forming the quadriceps tendon. From this point, the quadriceps tendon continues distally to insert on the patella.
Contraction of the vastus lateralis draws the patella towards the anterior surface of the femur. The patellar ligament connects the patella to the tibial tuberosity on the anterior surface of the tibia, so that anterior movement of the patella also draws the tibia anteriorly. The net result of the contraction of the vastus lateralis is therefore extension of the leg at the knee.
Like all skeletal muscles, the vastus lateralis is made of many skeletal muscle fibers (cells) surrounded by connective tissue. A layer of fibrous connective tissue known as the endomysium wraps each muscle fiber. Another layer of connective tissue known as the perimysium further wraps groups of muscle fibers, known as fascicles. Blood vessels and nerves pass through the spaces between fascicles to provide nutrients, oxygen, and nerve signals to the muscle fibers. All of the fascicles, vascular tissue, and nervous tissue in the muscle are wrapped up in the epimysium, which forms the outer layer of the muscle. At the ends of the muscle, the endomysium, perimysium, and epimysium continue beyond the ends of the muscle fibers to form the tendons that bind the vastus lateralis to the femur and patella.
Prepared by Tim Taylor, Anatomy and Physiology Instructor