What Is the Structure of Skeletal Muscles?

Skeletal muscle is a type of striated muscle that attaches to bones.

Chinese name: Skeletal muscle
Foreign name: skeletal muscle

Department: Anatomy
Belong to: Striated muscle
The human body has approximately: More than 600 skeletal muscles

Histological structure of skeletal muscle

Muscle cells are fibrous, unbranched, have obvious stripes, many nuclei, and are located below the cell membrane. Myocytes have many filamentous myofibrils arranged in parallel along the long axis of the cell. Each myofibril has a bright band (I band) and a dark band (A band) arranged alternately. Bright bands are lighter, while dark bands are darker. There is a brighter line in the middle of the dark band called the H-line. There is an M line in the middle of the H line. In the middle of the bright band, there is a darker line called the Z line. The section between the two Z-lines is called a sarcomere and is about 1.5 to 2.5 microns long. The adjacent muscle fibrils have bright bands on one plane and dark bands on one plane, which makes the muscle fibers appear light and dark horizontal stripes.

Skeletal muscles are made up of bundled muscle cells. Each cell has a different length, and the cells are closely arranged with complementary lengths. Each cell is covered with a slender reticular membrane called the endomysium; each muscle bundle is covered by a connective tissue membrane composed of glial and elastic fibers, called a myofibrium; There is a thick layer of connective tissue, called the epidural. The connective tissue of each membrane is continuous with each other, and the blood vessels and nerves distributed to the muscle enter along the connective tissue membrane. Skeletal muscle contraction is governed by consciousness, so it is also called "voluntary muscle". Contractions are characterized by fast and powerful but not long lasting.

Skeletal muscle movement

1 Skeletal muscle 1, classified or described by shape

Skeletal muscle shortens to produce movement, and the force of contraction is pulling force instead of pushing force. However, in some special cases, such as the bulging of the tympanic membrane in order to balance the air pressure on both sides of the tympanic membrane when the "popping sound acts on the ear", the phenomenon of muscular vein pumping is related to the effect of muscle abdominal expansion when the muscle contracts.

Most skeletal muscles move bones, but there are also muscles that move other parts of the body such as the eyes, lips, and scalp. The orbicularis oris muscles surround the mouth and play an important role in pronunciation and sucking. Although the tongue has no bones and joints, the hyoid bone only forms its basal part, but it can also move

2 Skeletal muscle 2, classified by motor unit

The main muscle that triggers specific movements of the body. Active contraction can produce intentional movement;

Antagonist muscles move against antigenic motor muscles. When the prime mover contracts, the antagonist muscles gradually relax to ensure the smooth movement process;

Synergistic muscles When the prime mover passes through more than one joint, contraction of the cooperative muscle can prevent one or more of the joints from interfering with the motion of the prime mover. In short, the synergistic muscles assist the movement of the prime mover;

When the movement occurs in the distal part of the limbs, the fixed muscle acts to stabilize the proximal parts of the limbs.

Skeletal muscle classification

Flat muscle : muscle fibers are parallel, often with aponeurosis, such as the external oblique muscle;

Pinnate muscles : the muscle bundles are arranged in a feather shape, and can be divided into half-pinions, pinions, or multipinions, such as the deltoid muscle;

Spindle muscle : spindle-shaped (muscle abdomen is thick and round, tapering at both ends), such as biceps;

Square muscle : square, with 4 approximately equal sides, for example: anterior spinalis;

Circular muscle or sphincter : distributed around openings or holes in the body. These openings are reduced when the muscles contract, for example, the orbicularis muscle can close the blepharoplasty.

Skeletal muscle exercise

Children and adolescents should pay attention to increase physical exercise appropriately, improve the toughness of skeletal muscles of the whole body, exercise appropriately, and do aerobic exercise as much as possible without harming the muscles, such as swimming and playing Tai Chi.