Batman certainly uses his anterior thigh muscles when rollerskating. I mean, look at that definition! When I saw this photo awhile back, it went right into my "Must Diagram" folder. Because it provides a wonderful, clear example of the anterior thigh landscape in a weight bearing leg.
The human thigh is divided into three muscle compartments. Within these compartments are specific muscle groups. The difference between a muscle compartment and a muscle group is this: A muscle compartment is based on location (such as anterior compartment, posterior compartment, etc.) and a muscle group is based on function (such as flexor group, adductor group, etc.)
The human thigh has three muscle compartments, and each of these compartments has its own muscle group:
• The anterior compartment (on the anterior side of the thigh) houses the leg extensor group (the muscles that extend, or straighten, the leg at the knee joint.)
• The posterior compartment (on the posterior side of the thigh) houses the leg flexor group (the muscles that flex, or band, the leg at the knee joint.)
• The medial compartment (on the medial side of the thigh) houses the leg adductor group (the muscles that adduct the thigh, or pull it inward toward the midline. More about the midline here.)
There is no lateral compartment on the thigh, although there is one structure on the lateral side of the thigh that does not belong to any specific compartment-- the iliotibial band. We can see the iliotibial band when drawing the figure and we discussed it briefly in a previous post, The Lateral Knee: A Change of Scenery. In the photo shown here, we can also see tensor fasciae latae, the muscle responsible for tensing the iliotibial band, on the lateral side of the thigh. (Tensor fasciae latae means tensor of the wide band.)
OK, let's diagram this thing out:
Here we see three muscles of the thigh's anterior compartment, plus a few other structures. (As a side note, there are actually four muscles in the anterior compartment, but one is not superficial so we can't see it.) The three anterior compartment muscles that we can see here are rectus femoris (a bipennate muscle that runs down the middle of the anterior thigh, directly above the patella,) vastus medialis, and vastus lateralis. The fourth anterior compartment muscle, which we cannot see on the surface, is called vastus intermedius.
Because there are four muscles in the anterior compartment that all insert into the same tendon, they are often collectively referred to as the quadriceps, which means four-headed muscle. And the tendon into which they insert is called the quadriceps tendon. You might sometimes see this referred to as the patellar tendon, as it attaches superiorly to the patella.
There will be more detailed thigh posts later, in which we'll explore each compartment much more thoroughly. But next time, we'll be returning to the elbow joint. See you then!