Our legs are responsible for propelling us through space when we walk, run or perform similar movements. They also support the rest of the body when standing and work to provide balance for the body while it is in motion and at rest. Most of these functions are performed by several important muscles in the hips, legs and ankles, as well as the major nerves which innervate these muscles. This article will discuss the anatomy and function of these important leg muscles and nerves.
What are the main leg muscles?
While the muscles of the hips and buttocks are not technically part of the legs, they are important for certain leg movements, support and balance, so we’ll begin from the hip, butt and pelvic region and work our way down.
The major muscles in the hip area are the gluteus maximus, gluteus medius, gluteus minimus, the adductor muscles, rotator muscles such as the piriformis and pectinius, and muscles which are located in the hip region but primarily affect other body parts, such as the rectus femoris and sartorius muscles. These muscles allow the leg to bend and rotate at the hip joint. Most of these muscles have the ability to cause more than one type of movement, and most movements require that several of these muscles engage simultaneously.
Muscles of the upper leg
The thigh muscles are composed primarily of the quadriceps group (anterior) and the hamstring group (posterior). The quadriceps group contains four muscles: the tensor fasciae latae, rectus femoris, vastus lateralis, and vastus medialis. The hamstrings group is composed of the biceps femoris, semitendinosus and semimembranosus muscles. The thigh also contains a group of adductor muscles, which are responsible for pulling the legs towards each other (the gluteus muscles work as abductors, working to draw the legs out away from each other). The sartorius muscle, which is the longest muscle in the human body, also runs through the thigh and helps support other muscles with flexion (bending), abduction and rotation in the hip as well as bending of the knee joint.
Muscles of the lower leg
The most important muscles of the lower legs are the calf muscles (posterior) and shin muscles (anterior). The calf muscles include the gastrocnemius and soleus, which pull the heel up when walking or standing on your toes. The main muscle of the shin is the tibalis anterior, along with other muscles like the peroneus longus, peroneus brevis and extensor digitorum longus. These muscles pull the toes up while walking or flexing your foot.
Nerves in the leg
The leg contains both sensory and motor nerves, but since movement and balance is their primary function, predominantly motor nerves are found in the hip, upper leg and lower leg. The nerves in the leg stem from spinal nerves in the lumbar and sacral areas of the lower back. Nerves originating in L1-L4 spinal nerves form a network known as the lumbar plexus, while the network of nerves coming from L4, L5 and S1-S4 is called the sacral plexus.
The most important nerves in the lumbar plexus are the femoral nerve, saphenous nerve, obturator nerve and the lateral femoral cutaneous nerve. The primary nerve in the sacral plexus network is the sciatic nerve, which splits to form the tibial and fibular nerves. All of these nerves branch off into many smaller nerves which either receive sensory information (temperature, pressure, equilibrium, pain, etc.) or send motor impulses, causing the muscles to move.
Proper communication between the important leg muscles and nerves is necessary for the coordinated movements and balance that allow us to carry out our daily activies.