The quadriceps, often known as ‘quads,’ consist of four muscles located in front of the thighs. These muscles act together to extend the knee, taking the leg from a bent position to a straight position. The muscles originate from different points on the pelvis and femur, allowing them to work together effectively to produce movements such as walking, running, squatting, and jumping. Each muscle of the quadriceps has its own distinct insertion point, but for brevity, we’ll focus on the main actions of the quads.

Functions:

Knee extension: One of the main functions of the quadriceps  is to extend (straighten) the knee joint. This range of motion is important for activities such as standing from a sitting position, walking, running, and jumping.

Stability: The quadriceps help stabilize the knee joint during heavy work by providing support and preventing excessive movement or rotation of the knee. 

Slowing down: During activities such as running or jumping, the quadriceps muscles help slow the forward movement of the leg, maintain momentum, and prevent hyperextension of the knee.

Hip flexors: One of the quadriceps muscles, the rectus femoris, also acts as a hip flexor and helps lift the hips toward the body. 

Postural support: The quadriceps muscles help maintain proper posture by stabilizing the lower body and supporting the spine and pelvis when standing or performing various movements.

Overall, the quadriceps play an important role in lower body movement, stability, and overall functional ability, making them essential for daily activities and athletic performance.