The rectus femoris muscle is one of the four
quadriceps muscles of the
human body
The human body is the entire structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently Organ (biology), organs and then Organ system, org ...
. The others are the
vastus medialis
The vastus medialis (vastus internus or teardrop muscle) is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group.
Structure
The vastus medialis is a muscle presen ...
, the
vastus intermedius (deep to the rectus femoris), and the
vastus lateralis. All four parts of the quadriceps muscle attach to the
patella (knee cap) by the
quadriceps tendon.
The rectus femoris is situated in the middle of the front of 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 ...
; it is
fusiform
Fusiform (from Latin ''fusus'' ‘spindle’) means having a spindle (textiles), spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon (geometry), lemon-shape, but often implies a focal broadening of a ...
in shape, and its superficial fibers are arranged in a
bipenniform manner, the deep fibers running straight () down to the deep
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 ...
. Its functions are to
flex the thigh at the
hip joint and to
extend the
leg
A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...
at the
knee
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 ...
joint.
Structure
It arises by two tendons: one, the anterior or straight, from the
anterior inferior iliac spine; the other, the posterior or reflected, from a groove above the rim of the
acetabulum
The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint.
Structure
The ...
.
The two unite at an acute angle and spread into an aponeurosis that is prolonged downward on the anterior surface of the muscle, and from this the muscular fibers arise.
The muscle ends in a broad and thick aponeurosis that occupies the lower two-thirds of its posterior surface, and, gradually becoming narrowed into a flattened tendon, is inserted into the base of the
patella.
Nerve supply
The neurons for voluntary thigh contraction originate near the summit of the medial side of the precentral gyrus (the primary motor area of the brain). These neurons send a nerve signal that is carried by the corticospinal tract down the brainstem and spinal cord. The signal starts with the upper motor neurons carrying the signal from the precentral gyrus down through the internal capsule, through the cerebral peduncle, and into the medulla. In the medullary pyramid, the corticospinal tract decussates and becomes the lateral corticospinal tract. The nerve signal will continue down the lateral corticospinal tract until it reaches spinal nerve L4. At this point, the nerve signal will synapse from the upper motor neurons to the lower motor neurons. The signal will travel through the anterior root of L4 and into the anterior rami of the L4 nerve, leaving the spinal cord through the lumbar plexus. The posterior division of the L4 root is the femoral nerve. The femoral nerve innervates the quadriceps femoris, a fourth of which is the rectus femoris. When the rectus femoris receives the signal that has traveled all the way from the medial side of the precentral gyrus, it contracts, extending the knee and flexing the thigh at the hip.
Function
The rectus femoris,
sartorius, and
iliopsoas are the flexors of the thigh at the hip.
The rectus femoris is a weaker hip flexor when the knee is extended because it is already shortened and thus suffers from
active insufficiency; the action will recruit more
iliacus,
psoas major
The psoas major ( or ; from ) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In other animals, this muscle is e ...
,
tensor fasciae latae, and the remaining
hip flexors than it will the rectus femoris.
Similarly, the rectus femoris is not dominant in knee extension when the hip is flexed since it is already shortened and thus suffers from active insufficiency. In essence: the action of extending the knee from a seated position is primarily driven by the
vastus lateralis,
vastus medialis
The vastus medialis (vastus internus or teardrop muscle) is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group.
Structure
The vastus medialis is a muscle presen ...
, and
vastus intermedius, and less by the rectus femoris.
In the other extreme, the muscle's ability to flex the hip and extend the knee can be compromised in a position of full hip extension and knee flexion, due to
passive insufficiency.
The rectus femoris is a direct
antagonist
An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain.[hamstring
A hamstring () is any one of the three posterior thigh muscles in human anatomy between the hip and the knee: from medial to lateral, the semimembranosus, semitendinosus and biceps femoris.
Etymology
The word " ham" is derived from the Old ...](_b ...<br></span></div> to the <div class=)
s, at the hip and at the knee.
Clinical significance
Strain
Rectus femoris strain, referred to as hip flexor strain, is an injury commonly at the tendon that attaches to the patella or in the muscle itself. The injury is usually a partial tear, but could be a full tear. The injury is caused by a forceful movement related to sprinting, jumping, or kicking and is common in sports like football or soccer. The rectus femoris is prone to injury, since it crosses both the knee and the hip. Symptoms include a sudden sharp pain at the front of the hip or in the groin, swelling and bruising, and an inability to contract the rectus femoris with a full tear.
Avulsion fracture
The rectus femoris tendon can cause a fragment of
anterior inferior iliac spine of the hip to avulse in what is known as an
avulsion fracture. This is due to forceful contraction of the muscle that generates a force greater than that which holds the bone together. This is a well recognized, but unusual
sports injury
Sports injuries occur during participation in sports or exercise in general. Globally, around 40% of individuals engage in some form of regular exercise or organized sports, with upwards of 60% of US high school students participating in one or ...
that can affect young athletes.
References
External links
PTCentral
{{Authority control
Hip flexors
Knee extensors
Muscles of the quadriceps
Anterior compartment of thigh
Muscles of the lower limb