You hear them referred to as your "gams," "poles" or "limbs." But, whatever you call them, your legs are composed of bones, muscles, tendons and ligaments. This soft tissue works together -- with your bones -- to help your legs stretch, bend, flex and perform other general movements.
Your leg has several primary groups of muscle as well as several tendons. Tendons connect your muscles to your bones and act as cables, allowing your bones to move your muscles.
Your quadricep muscles, also known as quads, consist of four muscles that compose the front of your leg; hence the name quads --meaning four. This is the group of muscles that you often see body builders flexing, which protrude just above the knee and take up most of the upper leg. They consist of the rectus femoris, vastus intermedius, vastus lateralis and the vastus medialis. These four muscles overlap each other and work together to straighten the knee and help you perform exercises such as squats, lunges and leg extensions.
Your hamstrings are the muscles that compose the back of your legs and consist of a group of three muscles. The three muscles include the biceps femoris, semimembranosus and semitendinosus. Unlike your quads, these muscles help you bend your knee and extend, or straighten, your hip and perform exercises such as raising your knees to your chest or making your heels touch your buttocks.
Quad and Patellar Tendons
Your quad and patellar tendons are located within a close proximity because each of them help control your quadricep and knee muscles. Your knee cap is also called the patellar bone, and the patellar tendon connects part of your quad muscles to your knee cap so when your brain tells your muscle to straighten your leg, it can do so by the force of your knee cap moving.
Your hamstring muscles connect to the back of your knee via the hamstring tendon. This tendon helps your leg bend when you raise your knee. Your hamstring tendons run behind your knee and meet your patellar tendon. All of these tendons protect and house the four ligaments inside of your knee, including your medial collateral ligament, lateral collateral ligament, anterior cruciate ligament and posterior cruciate ligament. These ligaments are often referred to as your MCL, LCL, ACL and PCL; all of them connect your femur to your tibia but in different positions.
Calves and Achilles Tendon
Two muscles make up the calves of the lower leg. The gastrocnemius is the bulging muscle that's most visible. It allows your foot to flex as you walk or run. It's also instrumental in bending the knee.
The soleus muscle lies underneath the gastrocnemius. It's flat and thick, rising from the bones of the tibia and fibula, and works to extends to the heel. It also assists in plantar flexion of the foot.
The soleus attaches at the Achilles tendon, a thick band of connective tissue at the back of your ankle and heel. It connects your calf to your heel and works as you push off to take a step. This tendon is often irritated by overuse or too quick of training progression.