The vastus lateralis (), also called the vastus externus, is the largest and most powerful part of the quadriceps femoris, a muscle in the

thigh In 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 bone tissu ...

. 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 A tendon or sinew is a tough band of dense fibrous connective tissue that connects muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tension. Tendons, like ligaments, are made of ...

attached to the

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

, and attaches to the outer border of the

patella The patella (: patellae or patellas), 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 m ...

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

quadriceps tendon In human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and micros ...

, which travels over the knee to connect to the

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

. The vastus lateralis is the recommended site for

intramuscular injection Intramuscular injection, often abbreviated IM, is the medical injection, injection of a substance into a muscle. In medicine, it is one of several methods for parenteral, parenteral administration of medications. Intramuscular injection may be ...

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 is a line upon the anterior aspect of the proximal end of the femur, extending between the lesser trochanter and the greater trochanter. It is a rough, variable ridge. Structure The intertrochanteric line marks the bound ...

; the lower, anterior borders of the greater trochanter, to the outer border of the gluteal tuberosity, and the upper half of the outer border of the

linea aspera The linea aspera () 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 is a prominent ...

. These form an

aponeurosis An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable ...

, 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 The gluteus maximus is the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in ...

muscle, and from the

septum In biology, a septum (Latin language, Latin for ''something that encloses''; septa) is a wall, dividing a Body cavity, cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Hum ...

between the vastus lateralis and short head of the

biceps femoris The biceps femoris () is a muscle of the thigh located to the posterior, or back. As its name implies, it consists of two heads; the long head is considered part of the hamstring muscle group, while the short head is sometimes excluded from this ...

. 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 hu ...

Innervation

The vastus lateralis muscle is innervated by the muscular branches of the

femoral nerve The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. It is the largest branch of the lumbar plexus. Structure The femoral nerve is the major nerve supplying the ant ...

(L2, L3, and L4).

Additional images

File:Slide8www.JPG, Vastus lateralis muscle File:Im-vastus-lateralis.png, Site for

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