What Is A Muscle?
Muscles are contractile tissues that allow the performance of different gestures and in particular to animate certain parts of the body. The shape of the muscles can be elongated, flat, or circular depending on their position in their body and their function. The whole body muscles represent 30 to 40% of the total body weight. They are mainly made up of water (80%), but also contain proteins (17%), glycogen (1%), lipids (1%) and mineral salts (1%).
List Of Main Muscles
The muscles are distributed in the form of muscle groups according to their anatomical location and their common function:
- The muscles of the head allow to control the movements of the eyes and the face to show expressions but also to allow chewing for example. We mainly find the masseter, zygomatic, occipitofrontal, or orbital muscle of the lips or the corrugator (around the eyes).
- The neck muscles allow you to orient your head in all directions and lift your shoulders. We mainly find the scalene muscles, the Sterno-cleido-mastoid muscle, or the trapezius muscles.
- The core muscles are mainly involved in breathing and movement of the spine. The diaphragm muscle is one of the most important, but we also find the pectoralis major, the deltoids, the dorsal fin, the intercostal muscles, the lumbar muscle, or the erector muscles of the spine.
- The muscles of the upper limbs such as the biceps, the triceps, the flexors of the forearm, or the extensors of the forearm and the muscles of the fingers, which allow you to pick up objects, lift, throw or raise your arms.
- The muscles of the lower limbs such as the glutes, the abductors, the adductors, the hamstrings, the quadriceps, the twins, or the muscles of the feet which make it possible to walk, run, sit or jump.
Types Of Muscles
There are three types of muscles depending on their location and their function:
- Smooth muscles, such as those present in the stomach, which function without voluntary stimulus (i.e. without the will).
- The striated heart muscle (the myocardium) which is a muscle different from the others, in particular, because it is subjected to the influence of hormones, and contracts involuntarily.
- The skeletal striated muscles which are linked to the bones and allow them to move. They are controlled by the will.
Examples Of Muscle Diseases
Muscle can be the seat of various pathologies:
- Myoma, a benign tumor of muscle tissue, which can affect any smooth muscle tissue or, more rarely, striated muscle fibers such as the myocardium and skeletal muscles.
- Myopathies, muscle diseases responsible for muscle weakness or exercise intolerance with pain, cramps, and a feeling of exhaustion. They can go as far as episodes of muscle destruction (rhabdomyolysis) caused by exercise. They are most often genetic and currently difficult to treat.
- Neuromuscular diseases that affect the nerve cells that control the muscles. They often cause muscle wasting, that is, a loss of volume and function. This is the case for example of spinal muscular atrophies, amyotrophic lateral sclerosis, peripheral neuropathies, or myasthenia gravis.
- Trauma (especially in athletes), which can appear suddenly or chronically. They generally cause pain during or after exercise with functional impotence. They range from simple contracture or stiffness to elongation and even tearing (breakdown).
To prevent any muscle problems during physical activity, do not forget to warm-up well before the practice, to drink during the effort and to stretch afterward. In case of pain or discomfort, it is advisable to stop all activity and consult your doctor.
The Role Of Muscles In The Human Body
Muscles are active organs, always acting in groups of two opposing or opposite muscles. They cause massive displacement of the bones on which they are firmly fixed by tendons. The muscles are also contractile and elastic organs: they shorten or lengthen. When they contract, it is always to respond to nervous messages.