Leg Muscles: Types, Location, Characteristics And Functions
The musculoskeletal system is made up of the osteoarticular system (bones and joints) and the skeletal muscles of the body, that is, those that respond to voluntary actions To give you an idea of the work of art of biomechanics that we have in our body, just say that we have 206 bones, 360 joints (86 of them in the skull) and more than 600 skeletal muscles, all of them with a common task: that we can maintain our shape and move.
Voluntary musculature (skeletal or striated) makes up approximately 40% of an adult man’s weight, so its functionality counts for itself. If we look at the legs, the third lower pelvic segment between the knee and the ankle, it is estimated that a human being walks about 3.5 billion kilometers throughout their entire life. For this reason, the leg muscles must be prepared for light but continuous exercise throughout our existence.
For all these reasons, it is also common to see how overweight and obese people have serious problems moving around the lower body. An added body kilogram is equivalent to 7 more in the knee portion, so increasing 10 kilos of mass, theoretically, is associated with 70 more kilograms of pressure in this joint.
With all this data in hand, it is more than clear to us that the leg is an essential anatomical section of the human being, both for locomotion and for supporting our weight in a three-dimensional environment. In honor of these structures, today We present all the muscles of the legs and their particularities
As we have said, the term “leg” refers to the lower extremity of the human body, which runs from the trunk to the foot In some contexts it is considered to also include the foot, and in others the thigh is excluded. In any case, we are going to perceive the structure as a “whole” at an anatomical level, spanning from the base to the tip of the fingers. We start by naming the muscles in the anterior compartment of the leg.
Here we find 4 well-differentiated muscle groups: tibialis anterior, extensor digitorum longus muscle, the extensor hallucis longus muscle (extensor hallucis) and the third peroneal muscle. We tell you its particularities.
1.1 Tibialis anterior
The tibialis anterior, as its name indicates, accompanies the tibia on its lateral surface The contraction of the tibialis anterior stabilizes the ankle, especially at the moment when the sole of the foot makes contact with the surface of the ground during the action of walking.
In general, its function is to keep the leg stable during walking, regardless of the condition of the terrain or its inclination.
1.2. Extensor digitorum longus muscle (EDL)
We are dealing with a penniform muscle (shape similar to that of a feather) innervated by the deep peroneus. It is an important dorsiflexor and, therefore, has the function of producing simultaneous extension of almost all the toes of the foot except the fat one.
It originates from the lateral condyle of the tibia and the medial surface of the fibula. The fibers of this muscle converge into a tendon, which travels along the dorsal surface of the foot, to split into 4 units that are inserted into each toe.
1.3. extensor hallucis muscle
As you can imagine, this is the muscle responsible for the extension of the big toe, but also for the dorsiflexion of the sole of the foot (along with the extensor digitorum longus). It originates on the medial surface of the shaft of the fibula and inserts into the phalanx of the big toe
1.4. Third peroneal muscle
This is a small muscular belly, located between the anterior and external portion of the leg. It originates with the EDL on the medial surface of the fibula, and travels with it for a certain stretch, until it reaches the dorsal surface of the foot. Here, the third peroneal muscle is divided and anchored to the fifth metatarsal. Along with other muscles, it is responsible for flexion and eversion of the foot
We continue our tour, this time on the side of the leg, paying attention to the following muscle groups: the peroneus longus and the peroneus brevis. We go with them.
2.1. Long peroneus
This muscle is located on the lateral and external surface of the leg. It originates on the external surface of the fibula and the tibial condyle, fusing along its course into a tendon that inserts into the medial cuneiform and the base of metatarsal I. Its main function is to extend the foot over the leg, take it outwards and allow it to perform a rotation movement
2.2. Short peroneus
Located on the outside of the leg and below the knee, this muscle is responsible for allowing the eversion of the foot. It is inserted into the anterolateral surface of the fibula shaft and is anchored on a tubercle associated with metatarsal V
3. Muscles in the posterior compartment of the leg
We speed up the process, because in this last section, a total of 7 muscles await us that must be described, at least briefly, which in turn are organized into two faces (superficial and deep, divided by a fascia). Let’s go there.
3.1. Gastrocnemius
We are entering familiar territory, since this muscle divided into two halves is what we know popularly as “the calves.” First of all, it should be noted that it has two “heads”, one medial and one lateral, which converge in the ventral section. It is located on the soleus muscle and occupies a large part of the back of the leg, from the knee to the ankle It is the main engine of the beginning of physical walking.
3.2. Plant
The plantaris muscle is in a deeper plane than the gastrocnemius and is much smaller in size, with a thin diameter. It is absent in 10% of the world population and its function is very weak so we are not going to dwell on it any longer.
3.3. Soleus
As we have already said previously, it is located below and behind the gastrocnemius. Curiously, It is called soleus because of its flattened and circular shape which makes it look like a sole.
The muscles that we have mentioned so far (gastrocnemius, plantar and soleus) form the external face of the posterior compartment of the leg. From now on, the following muscle groups are located in the deep section of it.
The popliteus is located at the top of the leg, “above the knee.” It is located in front of the gastrocnemius and is short, flattened and triangular in shape. Its function is to laterally rotate the femur on the tibia, thus allowing flexion of the knee joint.
3.5. Posterior tibial
Elongated in shape, This muscle is located between the flexor digitorum longus and the flexor hallucis, old acquaintances that we have already addressed. Its function is to allow adduction of the foot, stabilize the plantar vault and allow plantar flexion of the foot.
3.6. flexor digitorum longus muscle
This muscle originates from the middle part of the posterior aspect of the tibia. While the extensor digitorum longus muscle (EDL) was responsible for the extension of the 4 fingers this is what allows its bending.
3.7. flexor hallucis longus muscle
The same premise as the previous case, but with the big toe. It’s that simple.
Summary
As you may have seen, we have counted a total of 13 muscles: 4 in the anterior compartment, 2 in the lateral and 7 in the posterior. Without a doubt, the posterior side is the one that most resonates with all of us, since here are the calves, the soleus or the popliteus, muscle groups that many of us have had to learn during a biology lesson.
Except for the plantaris, all of these muscles play an essential role in the functioning of the leg and feet alike. Thanks to them, we are able to move effectively at different speeds and on different terrain.
