The vastus lateralis (), also called the vastus externus, is the largest and most powerful part of the

quadriceps femoris The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

, a muscle in the

thigh In human anatomy, the thigh is the area between the hip ( pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of ...

. Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward. It arises from a series of flat, broad tendons attached to the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

, and attaches to the outer border of the

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...

. It ultimately joins with the other muscles that make up the quadriceps in the

quadriceps tendon In human anatomy, the quadriceps tendon works with the quadriceps muscle to extend the leg. All four parts of the quadriceps muscle attach to the shin via the patella (knee cap), where the quadriceps tendon becomes the patellar ligament. It att ...

, which travels over the knee to connect to the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

. The vastus lateralis is the recommended site for intramuscular injection in infants less than 7 months old and those unable to walk, with loss of muscular tone.Mann, E. (2016). ''Injection (Intramuscular): Clinician Information.'' The Johanna Briggs Institute.

Structure

The vastus lateralis muscle arises from several areas of the

, including the upper part of the

intertrochanteric line The intertrochanteric line (or ''spiral line of the femur''White (2005), p 256 ) is a line located on the anterior side of the proximal end of the femur. Structure The rough, variable ridge stretches between the lesser trochanter and the greater ...

; the lower, anterior borders of the

greater trochanter The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Stan ...

, to the outer border of the

gluteal tuberosity The gluteal tuberosity is the lateral one of the three upward prolongations of the linea aspera of the femur, extending to the base of the greater trochanter. It serves as the principal insertion site for the gluteus maximus muscle. Structure T ...

, and the upper half of the outer border of the

linea aspera The linea aspera ( la, rough line) is a ridge of roughened surface on the posterior surface of the shaft of the femur. It is the site of attachments of muscles and the intermuscular septum. Its margins diverge above and below. The linea aspera ...

. These form an aponeurosis, a broad flat tendon that covers the upper three-quarters of the muscle. From the inner surface of the aponeurosis, many muscle fibers originate. Some additional fibers arise from the tendon of the gluteus maximus muscle, and from the septum between the vastus lateralis and short head of the biceps femoris. The fibers form a large fleshy mass, attached to a second strong aponeurosis, placed on the deep surface of the lower part of the muscle. This lower aponeurosis becomes contracted and thickened into a flat tendon that attaches to the outer border of the

, and subsequently joins with the quadriceps femoris tendon, expanding the capsule of the

knee-joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the h ...

Innervation

The vastus lateralis muscle is innervated by the muscular branches of the femoral nerve (L2, L3, and L4).

Additional images

File:Slide8www.JPG, Vastus lateralis muscle File:Im-vastus-lateralis.png, Site for intramuscular injection into the vastus lateralis

References

External links

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PTCentral
{{Authority control Knee extensors Muscles of the quadriceps Anterior compartment of thigh Muscles of the lower limb