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 bone ...
. 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, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
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 with ...
, 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 m ...
. 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
Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have ...
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
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 with ...
, 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 t ...
; 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 asper ...
. These form an
aponeurosis
An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join musc ...
, 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. 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 the human ...
muscle, and from the
septum
In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate.
Examples
Human anatomy
* Interatri ...
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 has two parts, one of which (the long head) forms part of the hamstrings muscle group.
Structure
It has two heads of origin:
*the ''long h ...
.
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
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 m ...
, 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 (L2, L3, and L4).
Additional images
File:Slide8www.JPG, Vastus lateralis muscle
File:Im-vastus-lateralis.png, Site for intramuscular injection
Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have ...
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