Rectus femoris muscle

Rectus femoris muscle
Rectus femoris.png
Muscles of the iliac and anterior femoral regions. (Rectus femoris visible near center.)
Details
Origin anterior inferior iliac spine and the exterior surface of the bony ridge which forms the groove on the iliac portion of the acetabulum
Insertion inserts into the patellar tendon as one of the four quadriceps muscles
Artery descending branch of the lateral femoral circumflex artery
Nerve femoral nerve
Actions knee extension; hip flexion
Antagonist Hamstring
Identifiers
Latin Musculus rectus femoris
TA A04.7.02.018
FMA 22430
Anatomical terms of muscle

The rectus femoris muscle ( s/) is one of the four quadriceps muscles of the human body. The others are the vastus medialis, 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) via the quadriceps tendon.

The rectus femoris is situated in the middle of the front of the thigh; it is fusiform in shape, and its superficial fibers are arranged in a bipenniform manner, the deep fibers running straight (rectus) down to the deep aponeurosis. Its functions are to flex the thigh at the hip joint and to extend the leg at the knee joint. [1]

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 two unite at an acute angle, and spread into an aponeurosis which is prolonged downward on the anterior surface of the muscle, and from this the muscular fibres arise.

The muscle ends in a broad and thick aponeurosis which 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. [2]