Anatomy in detail:

4. RECTUS FEMORIS

The rectus femoris muscles lie over the anterior (front) of the femur, extending from pelvis to tibia, spanning the hip and knee joints.

rectus ≅ straight

femoris ≅ femur

When fully engaged, the rectus femoris muscles correctly position the legs to the torso.

rectus femoris keeping it simple

Skeleton front off-center view. The left leg shows the rectus femoris muscle from hip to shin. The right leg shows the other 3 muscles of the quadriceps femoris - the vastus medialis, vastus intermedius and vastus lateralis with attach to the top of the femur. The hip joint can be seen on the right leg. The distal tendons of the four muscles merge to form the common tendon of the quadriceps which attaches to and contains the patella. The connective tissue continues as the patellar ligament to the tibial tuberosity. The rectus abdominis muscles are also shown, up the front of the abdomen from pubic symphysis to chest.

The rectus femoris and the quadriceps femoris.

The rectus femoris is part of the quadriceps femoris muscle group, along with the 3 "vasti" muscles: the vastus lateralis, vastus intermedius and vastus medialis.

The rectus femoris is the only muscle of the quadriceps that attaches to the pelvis. The three vasti attach to the top of the femur.

Distally, the four muscles of the quadriceps femoris merge into the common tendon of the quadriceps.

The rectus femoris can be thought of as the lead muscle of the quadriceps, crossing both hip and knee thus aligning these joints.

Image showing pelvic bones, femur, tibia and fibula and the rectus femoris muscles. The rectus femoris are pole-likes muscle down the front of the thigh from the ilium of the pelvis (front ridge of the hip bone) to the tibial tuberosity of the tibia (bony lump near the top), attaching via the patellar ligament. The patella/kneecap sits within the ligamentous attachment. The rectus femoris crosses both hip and knee joints so when fully active it positions the leg in the correct position in relation to the rest of the body. Feel for your kneecaps lifting.

Distal attachment of the rectus femoris.

The common tendon of the quadriceps attaches to the patella, the largest sesamoid bone (a bone embedded in connective tissue) in the human body.

From the patella, the connective tissue continues as the patellar ligament.

The patellar ligament attaches to the tibial tuberosity located on the proximal, anterior aspect of the tibia. The tibial tuberosity is the distal attachment of the rectus femoris.

Proximal attachments of the rectus femoris.

The proximal attachments of the rectus femoris to the pelvis are commonly described as "to the ilium of the pelvis via two heads - the straight head and the reflected head". But it is not that simple. Variations in the pelvic attachments have been observed.

Image showing the possible attachments of the rectus femoris muscles to the pelvis and surrounding tissues. There is some variation between individuals in number and location of the attachments.

The tendon of the straight head attaches to the anterior inferior iliac spine.
The rectus femoris may also arise from the anterior superior iliac spine.
The tendon of the reflected head attaches in a groove above the superior rim of the acetabulum and the fibrous capsule of the hip joint. The reflected head may be absent.
A 3rd head may be present, attaching to the ilio-femoral ligament deeply, and superficially to the gluteus minimus tendon as it attaches to femur.

Skeleton seen from the side showing the rectus femoris at the front of the femur from hip to shin, with the patella lying within the ligament/tendon of the muscle. An enlarged schematic picture of the rectus femoris when seen from the side shows the layers of connective tissue known as aponeuroses that sandwich the muscle fibres. A layer of connective tissue from the hip that extends down the front third of the muscle. Another layer at the bottom third at the back of the muscle extending to the patella.

The rectus femoris: Muscle tissue between aponeuroses.

The heads of the rectus femoris merge into an aponeurosis which continues distally on the anterior surface of the muscle.

The lower two-thirds of the posterior surface of the rectus femoris consists of a thick, broad aponeurosis that becomes the superficial, central part of the common quadriceps tendon.

4. RECTUS FEMORIS

The rectus femoris and the quadriceps femoris.

Distal attachment of the rectus femoris.

Proximal attachments of the rectus femoris.

The rectus femoris: Muscle tissue between aponeuroses.

OPTIMISING THE USE OF YOUR MUSCLES = BETTER HEALTH.