Your body has three types of muscle, but skeletal muscle is what allows you to move. It makes up the majority of your body's muscle mass and about 40 percent of your body's entire mass. Skeletal muscle is controlled both consciously and subconsciously, meaning you can control it if you wish to perform actions such as flexing. Skeletal muscle also is the only type of muscle that you can control and choose to move. The muscles in your legs are the main muscles your body uses to move.
Types of Muscle
Your body contains three types of muscle: skeletal, smooth and cardiac. Skeletal muscle makes up between 36 percent and 42 percent of your body mass. Ligaments and tendons connect and anchor skeletal muscle to bones. Skeletal muscle is what allows you to move and is controlled both consciously and subconsciously. Smooth muscle is located on the walls of organs and is controlled subconsciously. Cardiac muscle is located only in the heart and is controlled subconsciously.
Quadriceps
The quadriceps are the strongest muscles in the body relative to size and are responsible for straightening the knee. There are three heads, or separate muscles, that comprise the quadriceps. They are located on the front side of your thigh and go from the top of your knee to your hips. The rectus femoris is the largest of the three heads and extends from the top of the knee to just below the hip joint. The vastus lateralis is located on the outer portion of the thigh and is half the width of the rectus femoris, about four inches. Lastly, the vastus medialis is located above the knee on the inner portion of the thigh.
Hamstrings
The hamstrings contain three separate heads and are located on the back of the thigh. Biceps femoris is the largest of the heads and is located toward the outer portion of the thigh. The semitendinosus head is toward the outside of your thigh and along with the biceps femoris extends from the gluteus maximus to the back of the knee. The third head, semimembranosus, connects to the back of the knee. The hamstrings work together to bend the knee.
Calves
The gastrocnemius, commonly called the calf, is a small but strong muscle on the back of your lower legs. It is divided into a medial and lateral head; the medial head is larger. The calves assist in plantar flexing the foot, pointing it downward, as well as pushing off the ground during activities such as running and jumping.
References
- "Human Anatomy & Physiology (7th ed.)"; Pearson Benjamin Cummings; 2007
- Exercise Prescription: Quadriceps
Member Comments