Leg Muscles

Introduction

Human anatomy shows that the lower limb or the leg has two parts- the upper leg and the lower leg. The upper leg consists of the thigh that lies between the hip and the knee. The lower leg consists of the calf region that lies between knee and ankle and foot. Legs are anatomically composed of bones (femur, patella, tibia, and fibula) and muscles. Females have shorter femur and tibial length than the males. Legs are used to stand, run, dance, etc. In this tutorial, we will discuss the leg muscles in detail.

What are Leg Muscles?

Like other body parts, the legs have various muscles in the upper and lower leg. The upper leg muscles are grouped into gluteal, quadriceps, adductor and the hamstring group, whereas the lower leg muscles are grouped into flexor, extensor and the peroneal group.

Anatomy

Leg and foot muscles - location, function, shape and size

• Gluteal muscles are the part of the torso and legs. This group contains the muscles that are attached to the outer portion of the pelvis, such as gluteus medius, gluteus minimus, gluteus maximus and tensor fasciae latae. They occupy the lateral and posterior portions of the upper leg. The gluteal muscles move the femur to the hip joint. The gluteus minimus hides beneath the gluteus medius but all the three muscles seem to be in a separate shape. The gluteus maximus and gluteus medius make a butterfly (in males) and pear (in female) like shape in the torsos with a major fatty tissue layer.

  The Gluteus maximus is the largest among all, and dominates the hip region occupying the bottom angle of the sacrum. Gluteus medius occupies the centre of pelvis bone between tensor fasciae latae and gluteus maximus as a bulge fan shaped muscle. Gluteus minimus is positioned behind the gluteus medius centrally on the pelvis. The tensor fasciae latae is teardrop shaped begins at the pelvis ASIS and flares after inserting fascia and iliotibial tract of femur greater trochanter.

• The quadriceps muscle that includes rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius, are the extensor group of upper leg bordered by sartorius muscles and tensor fasciae latae of upper leg with the iliotibial tract. They are merged with a tendon, located at the femur and pelvis, and insert in to the kneecap patella.

• The adductor muscles are the inner thigh muscles grouped into adductor magnus, adductor longus, adductor brevis, pectineus, and gracilis. They merge to contribute the upper leg cylindrical shape. These muscles are located at the lower pelvic ischium bone and pubic bone. They cover the backside of the femur while gracilis insert the knee joint to get attached with tibia.

• Sartorius includes the muscle group travelling diagonally on the thigh as an elongated strap between quadriceps to adductors and is the longest of all muscles.

• Hamstring muscles positioned at the posterior of the upper leg, grouped into biceps femoris, semitendinosus and semimembranosus.

• The flexors are the calf muscle located at the posterior of the lower leg. They are grouped into two headed gastrocnemius muscles, soleus muscle and plantaris. Gastrocnemius occupies the upper half, soleus located beneath this and plantaris is a tendon covered by gastrocnemius exposed at popliteal fossa, a small fat pad.

• The extensor muscles are found on the lower leg front region. They are grouped into tibialis anterior, extensor digitorum longus, extensor hallucis longus and peroneus tertius.

  Tibialis anterior travels leg obliquely in an elongated fusiform cordlike tendon, seems if the foot is lifted upward. The slender extensor digitorum longus is located next to tibialis. Extensor hallucis longus is a toe muscle located between tibialis and digitorum. Peroneus tertius is located between the front fibula to interosseous membrane inserts foot on fifth metatarsal.

• Peroneal muscles contain peroneal longus and peroneal brevis, positioned at the lateral region of the lower leg like an elongated bootstrap.

• The front part of the foot has tendons coming down from the muscle and enters into different toes. At the outer ankle bone there is a soft egg-like muscle named extensor digitorum brevis. At the side of the fifth little toe there is abductor digiti minimi which terminates at heel. The abductor hallucis located at the inner arch of the foot , allowing muscles to contract sideways of the large toe.

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Functions

• Gluteus maximus is a dominant extensor that helps bending the upper leg back from the hip joint and rotates it outwardly. Gluteus medius and gluteus minimus moves the upper leg in a sideway direction and to rotate inwardly. Tensor fasciae latae helps the upper leg move inwardly, forward and sideward and tense the iliotibial tract.

• The quadriceps muscle helps moving the upper leg at the hip joint and at the knee joint in lower legs and stabilizes the patella.

• The adductor muscle helps an outstretched sideway-positioned leg from back torso to a normal standing posture. It also helps bending the hip joint.

• Sartorius helps move the upper leg forward from hip joint, sideward from the mid bodyline, rotates outwardly and helps bending the lower leg from the knee joint.

• Hamstring muscles move the lower leg at the knee to bend, rotate outwardly being bent and straighten the upper leg at the joint of the hip.

• Gastrocnemius moves lower leg at knee joint in contraction, helps to lift the heel and tip-toeing. Soleus helps lifting heel when walking, stand tip-toeing and downward foot pointing actions. Plantaris lifts the heel up.

• Tibialis anterior moves the foot upward at the ankle joint and turns it inwardly. Extensor digitorum longus moves foot upward from ankle, raises the lesser toes upward. Extensor hallucis longus lifts toes and feet upwardly. Peroneus tertius lifts the foot upward at the ankle.

• Peroneal muscles help to move the foot outward at the ankle joint and stabilize the ankle.

• Extensor brevis straighten the lesser toe, abductor digiti minimi helps in sideward pulling and bending of the little toe.

Conclusion

Legs are one of the important organs of the human and contributes to half of the body. Parts of the leg include hip, thigh, knee, calf, ankle, foot, and toes. All of these parts have different muscles with specific functions. Muscle function affects our movements and postures. All the leg muscles and tendons are long and help us to stretch, walk, stand, bend, dance, carry our body weight, jump, flex and run and obviously contributes to shaping our leg precisely so that it can function properly without any discomfort.

FAQs

Q1. Name the large and small muscles of the leg.

Ans. The calves and the thigh muscles are the largest and the popliteus is the smallest muscle located behind the knee, attached with the tibia.

Q2. Why do the leg muscles contract?

Ans. The leg muscles are tender and get cramped whenever it is over exercised, dehydrated and strained. The accumulation of lactic acids on the muscles during heavy physical movements causes muscle contraction in legs.

Q3. What is the main reason for varicose vein disease?

Ans. If the leg veins fail to work properly in circulating the blood it would cause swelling and pain. Inflammation in the vein may damage valves of the leg veins that function poorly and make the distended vein visible beneath the skin. And further this leads to varicose vein disease.

Q4. Define charley horse cramp.

Ans. It's a cramp which often occurs due to forceful stretching or holding one position like flexing your legs upward to stretch calf muscle for a long time. It is an uncontrolled painful contraction.