Anatomy in detail.
The rectus femoris muscles run down the front of each thigh, from pelvis to tibia (hip bone to shin bone).
Part of the quadriceps femoris muscle group, along with the 3 "vasti" muscles: the vastus lateralis, vastus intermedius and vastus medialis (lateral, intermediate and medial). See illustration further down.
The rectus femoris is the 'guide' muscle for the rest of the quadriceps, attaching to the pelvis, whilst the 3 vasti muscles attach to the top of the femur (thigh bone). When fully engaged along their full length, the rectus femoris muscles correctly align the knee and hip joints, positioning each leg so that the other thigh muscles can work properly.
The distal (end furthest from the body) tendons of the quadriceps femoris muscles merge together to form the common quadriceps tendon which attaches to the patella (kneecap) and then continues as the patellar ligament to the tibial tuberosity of the tibia.
rectus ≅ straight
femoris ≅ femur
quadriceps ≅ 4 muscles in the femoris group
Working in conjunction with the gluteus maximus muscles, the rectus femoris muscles provide strength and stability for the legs to connect with the Base-Line muscles.
The 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 of the rectus femoris have been observed.
Anatomy - A Few More details.
The heads of the rectus femoris merge into an aponeurosis (thin sheet of strong connective tissue), from which the muscle fibres arise as the aponeurosis continues distally (away from the center of the body - in this case down the leg) on the anterior (front) surface of the muscle.
The lower two-thirds of the posterior (back) surface of the rectus femoris consists of a thick, broad aponeurosis that becomes narrowed into a flattened tendon attached to the patella. This forms the superficial, central part of the quadriceps tendon.
Without adequate engagement, areas of the other muscles in the leg 'take control', carrying the burden and repositioning the leg in relation to the pelvis. Rotations/twists/...
Movement should not be painful.
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