Leg muscles

What are leg muscles?

The leg muscles are the muscles that help us move from one place to another and support our weight when we are standing. They are what allow us to move the foot in relation to the leg and the leg in relation to the thigh when we sit, walk, run and do many other physical activities during the day, every day.

The legs represent the lower limbs of the human body and the bones that make them up belong to the appendicular skeleton, which is the part of the skeleton that includes the bones of both the hands, forearms and arms, as well as the thighs, legs. And feet; and the shoulder girdles (where the shoulders are) and pelvic (where the hips are).

So the legs, with their bones and the muscles that help to move them, belong to the locomotor system. Each leg of our body is made up of about 32 bones, which are associated with a large number of muscles that are between them and the skin that covers them..

To understand a little more the anatomical relationships of the muscles in the lower limbs, it is convenient to quickly mention the bones that compose them. Thus, from top to bottom (from the pelvic girdle to the foot) the bones of the legs are:

• Ilium, ischium and pubis: the hip bones, which represent the pelvic girdle, which joins the legs with the trunk bones.
• Femur: It is the longest bone in the human body and is located in the thigh.
• Tibia and fibula: the bones of the leg, between the knee and the foot.
• Talas, calcaneus, cuboid, medial cuneiform, intermediate cuneiform, lateral cuneiform, and navicular: the bones of the back of the foot, better known as the "tarsal bones.".
• Metatarsals and phalanges: the bones of the foot; they are 5 and 14, respectively.

Leg muscles and their functions

Leg muscles, as part of the musculoskeletal system, are striated skeletal muscles, which means that they are made up of long cells that contain contractile proteins arranged in such a way that, when viewed under the microscope, they have a striated appearance..

They are mostly long muscles, capable of stretching a lot. The contraction and relaxation of these is what makes possible the movement of the bones that are part of the legs, which helps us, among other things, to move.

The legs also have short muscles that provide stability to the joints (the contact / junction sites between two or more bones), the ability to rotate and perform "fine" movements, etc..

Hip and thigh muscles

In the thigh are the strongest muscles in our entire body, since they are the ones that have the responsibility of extending the knee so that it has a straight position, thus allowing the daily movement of the legs, either to walk, climb or descend stairs lift weight, etc.

These muscles, then, are the ones that support most of our body weight, which makes them very important to us..

The muscles of the anterior region of the thigh participate in flexion and lateral rotation of the hip, while the muscles of the posterior part extend, abduct and rotate the hip moderately.

The hips are associated with different types of muscles as well, which are divided into two regions, an anterior (in the same plane as our face) and a posterior (in the plane corresponding to our back or our back).

Hip muscles

In the posterior region of the hips are the muscles known as glutes; These are arranged in three layers and are known as:

• Gluteus maximus muscle: born in the ileum and inserted into the femur; It is the largest of the three and helps us maintain an upright posture, abduct the thigh, and rotate the thigh outward..
• Gluteus medius muscle: it is under the gluteus maximus and helps to abduct the thigh, as well as to rotate it inwards.
• Gluteus minimus muscle: it is the smallest and internal of the three and they act in conjunction with the gluteus medius.

Thigh muscles

The anterior region of the thigh is provided with the most colorful and largest muscles in our body: the sartorius muscle and the quadriceps, which is actually made up of 4 individual muscles: three of them superficial and one hidden..

• Sartorius muscle: it is the longest in the body and the most superficial in the anterior region of the thigh; it passes through both the hip and knee joints, and participates in hip flexion and thigh abduction; crosses the thigh diagonally.
• Rectus femoris muscle: is the central muscle of the three superficial muscles of the quadriceps.
• Vastus lateralis muscle: is on the outside of the thigh; It ranges from the upper end of the femur to the kneecap (the flat bone called patella, covering the joint).
• Vastus medialis muscle: it is a teardrop-shaped muscle, it is located on the inner thigh, it is the last of the three superficial muscles of the quadriceps.
• Vastus intermedius muscle: it is "hidden" by the rectus femoris muscle, it is the fourth muscle of the quadriceps.

In the anterior region there are also the muscles of the adductor group, which facilitate the movements of the leg contrary to those of abduction, that is, they allow us to close the legs. These muscles are as follows, and are located between the femur and the pubic bone of the hip:

• Adductor brevis muscle.
• Long adductor muscle.
• Adductor magnus muscle.

There are three main muscles in the posterior thigh region, which are commonly known as hamstring muscles. These and other important muscles in this region are:

• Semimembranosus muscle: on the inner edge of the back of the thigh.
• Semitendinosus muscle: in the middle region of the back of the thigh.
• Biceps femora musclel: in the outermost region, that is, on the lateral border of the back of the thigh.
• Gracilis muscle or internal rectus muscle: it is in the posterior mid-thigh region; arises in the pubis and inserts in the upper area of ​​the tibia.

Leg muscles

Although we know the leg as everything that is included between our hips and our feet, the region properly known as the leg is the one that encompasses the space between the knee and the foot, that is, where we have the calf.

These are some of the most important muscles in the lower part of our legs, specifically those in the anterior region:

• Tibialis anterior muscle.
• Long fibular muscle.
• Extensor pollicis longus muscle or common flexor muscle of the toes.
• Short fibular muscle.
• Extensor muscle of the great toe.
• Third fibular muscle.
• Superior extensor retinaculum muscle.

The superficial muscles of the posterior region of the leg are:

• Gastrocnemius muscle, better known as "the twins" is a muscle that is divided into two halves and is the most superficial of the calf.
• Plantar muscle.
• Soleus muscle.
• Popliteal muscle.
• Posterior tibial muscle.
• Long flexor muscle of the toes.
• Flexor hallucis longus muscle.

Foot muscles

The muscles of the foot are classified as extrinsic (if they are derived from the muscles of the lower leg) or intrinsic (if they are located specifically in the region of the foot).

The extrinsic muscles of the foot function in general movements of the foot such as flexion, rotation, inversion, etc. The intrinsic muscles are responsible for the "fine" actions of the feet, such as the movement of individual toes, for example..

Dorsal region:

• Extensor digitorum brevis: arises from the calcaneus bone and inserts into the proximal phalanges of the big toe and the long extensor tendons of fingers 2, 3 and 4.
• Extensor brevis brevis muscle: arises in the calcaneus and inserts at the base of the proximal phalanx of the big toe.

Plantar region:

This region is made up of 10 muscles separated into 4 "layers". The muscles in this part of our feet are very important, as they help us control the movement of the toes and stabilize the arch region of the foot..

• Abductor muscle of the big toe.
• Flexor brevis muscle of the toes.
• Short toe abductor muscle.
• Square plantar muscle.
• Lumbrical muscle.
• Flexor brevis muscle of the big toe.
• Adductor hallucis muscle.
• Short toe flexor muscle.
• Plantar interosseous muscle.
• Dorsal interosseous muscle.

References

1. Feneis, H., & Dauber, W. (2000). Pocket Atlas of Human Anatomy. Thieme.
2. García-Porrero, J. A., Hurlé, J. M., Padilla, G. B. (2005). Human anatomy (pp. 138-144). McGraw-Hill / Interamericana from Spain.
3. Kahle, W., Leonhardt, H., Platzer, W., Palmer, E., & Werner. Platzer. (2004). Color atlas and textbook of human anatomy. Vol. 1, Locomotor system. Thieme.
4. Kent, M., & Rhees, R. W. (2001). Schaum's easy outlines Human anatomy and physiology. London: McGraw-Hill, 2001.
5. Netter, F. H. (2006). Atlas of human anatomy. Philadelphia, PA: Saunders. Elsevier.