In Plain English
The quads are the large muscles covering the front of your thigh, extending from the pelvis and upper thigh to the shin through the kneecap. Made up of four individual muscles, they straighten the knee, help control bending under load, and, in the case of the rectus femoris, also help lift the thigh at the hip.
Technical Definition
The quads refer to the quadriceps femoris, a four-headed muscle group consisting of the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. Together, they insert via the quadriceps tendon into the patella before continuing through the patellar tendon to the tibial tuberosity. The primary function of all four heads is knee extension, while the rectus femoris also contributes to hip flexion due to its origin on the anterior inferior iliac spine. Collectively, the quadriceps generate force during locomotion while controlling and producing knee extension under load.



















