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Muscles of the chest
Last reviewed: 23.04.2024
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The muscles of the chest are arranged in several layers. More superficially lie those muscles that develop in connection with the laying of the upper limb. They connect the upper limb with the thorax. These include the large thoracic and anterior cog muscles. Each muscle has its own fascia. Ahead of the superficial muscles is a superficial (subcutaneous) fascia of the breast.
Deep layers of the musculature of the breast are represented by their own, autochthonous muscles, developing from the ventral divisions of the myotomes. These muscles begin and attach within the chest wall. These include the external and internal intercostal muscles, the subcostal muscles, the transverse muscle of the chest, the muscles that lift the ribs.
Together with the muscles of the breast, an anatomically and functionally well-known obstruction is described - the diaphragm - the main respiratory muscle, which develops from the ventral parts of the cervical myotomes.
Superficial muscles of the breast
The large pectoral muscle (m. Pectoralis major) is massive, fan-shaped, occupying a considerable part of the anterior wall of the thoracic cavity. Accordingly, the place of its origin in the muscles distinguish the clavicular part (pars clavicularis), which begins on the medial half of the clavicle; the sternocostalis (pars sternocostalis) - it originates on the front surface of the sternum and the cartilages of the upper six ribs, and the abdominal part (pars abdominalis), which begins on the anterior wall of the vagina of the rectus abdominis.
The small pectoral muscle (m. Pectoralis minor) is flat, triangular in shape, located directly behind the large pectoral muscle. The muscle begins on the II-V ribs, near their anterior ends. Heading upwards and laterally, it is attached by a short tendon to the coracoid process of the scapula.
The subclavian muscle (m. Subclavius) is of small size, occupying a slit-shaped gap between the first rib and the clavicle. It begins on the cartilage of the 1st rib, passes laterally and is attached to the lower surface of the acromial end of the clavicle.
The anterior serrate muscle (m. Serratus anterior) is broad, quadrangular in shape, is attached to the thorax from the side, forms the medial wall of the axillary cavity. It begins with large teeth on the upper eight or nine ribs and is attached to the medial margin and the lower corner of the scapula. The upper and middle muscle bundles lie horizontally, the lower fascicles are obliquely located and run from front to back and from below upwards.
Deep chest muscles
The outer intercostal muscles (mm., Intercostales externi) in number 11 on each side begin at the lower edge of the overlying rib, outside of its furrow, and, going down and forwards, attach to the upper edge of the underlying rib. The muscles occupy the intercostal spaces from the ribs of the ribs to the costal cartilages in the front, where their extension to the edge of the sternum is the outer intercostal membrane (membrane - membrana intercostalis externa).
Internal intercostal muscles (mm. Intercostales interni) are located inward from the external intercostal muscles. They occupy the intercostal spaces, starting from the edge of the sternum (at the true ribs) and the anterior ends of the cartilages of the false ribs and to the corners of the ribs from the rear, where the inner intercostal membrane (membrane intercostalis interna) serves as a continuation .
Subcostal muscles (mm. Subcostales) are formed by muscle and tendon bundles in the lower part of the posterior part of the inner surface of the chest wall. Begin on the X-XII ribs near their corners, are directed upward and laterally, they are thrown over one or two ribs and attached to the inner surface of the overlying ribs.
The transverse muscle of the breast (m. Transversus thoracis) is located on the posterior (inner) surface of the anterior thoracic wall. This muscle begins on the xiphoid process, the lower half of the sternum.
The transverse muscle of the breast
