Types of Quads
The Rectus femoris muscle is one of the four quadriceps muscles. It is located in the middle of the front of the thigh. It is responsible for knee extension and hip and thigh flexion.
The quadriceps femoris (/ ˈ k w ɒ d r ɪ s ɛ p s ˈ f ɛ m ər ɪ s /, also called the quadriceps extensor, quadriceps or quads), ... the tensor vastus intermedius.
The vastus lateralis (/ ˈ v æ s t ə s ˌ l æ t ə ˈ r eɪ l ɪ s, ˈ r æ-/), also called the ''vastus externus'' [citation needed] is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh.
The vastus medialis is a muscle present in the anterior compartment of thigh, and is one of the four muscles that make up the quadriceps muscle. The others are the vastus lateralis, vastus intermedius and rectus femoris.