Intercostal nerves

The anterior branches of the thoracic spinal nerves (ThI-ThxII) retain the metameric (segmental) structure. Eleven upper pairs of anterior branches are called intercostal nerves, the 12th intercostal branch is the subcostal nerve. Intercostal nerves innervate all the muscles and skin of the lateral and anterior sections of the thoracic and abdominal walls, the parietal pleura and peritoneum, and the mammary gland.

Intercostal nerves (nn. Intercostales) are directed laterally and forward in the intercostal spaces, the subcostal nerve - under the XII rib. Each intercostal nerve passes at the lower edge of the corresponding rib under the same artery and vein. From the place of origin to the angle of the rib, the nerves are covered with the intrasternal fascia and the rib part of the pleura. Further to the front, each of the nerves goes between the outer and inner intercostal muscles. Six pairs of lower intercostal nerves pass through the rib side of the diaphragm. Then they go obliquely forward and down between the inner oblique and the transverse abdominal muscles, giving them branches. The subcostal nerve passes on the outside of the square muscle of the waist.

Muscular branches (rr. Musculares) of the intercostal nerves innervate the external and internal intercostal muscles, the subcostal muscles; muscles that lift ribs; the transverse muscle of the chest, the posterior upper cog, the outer, inner oblique, transverse and straight mice of the stomach.

Cutaneous branches of the intercostal nerves are the anterior and lateral cutaneous branches (r. Cutaneus lateralis et cutaneus anterior). Depending on the location, the front and lateral cutaneous branches of the chest and abdomen are distinguished. Lateral cutaneous branches on their way to the subcutaneous tissue pass between the teeth of the anterior dentate muscle (in the chest region), below the external oblique muscle of the abdomen. Lateral cutaneous branches of IV-VI intercostal nerves are involved in the innervation of the mammary gland (lateral branches of the mammary gland, r. Mammarii laterales). In the composition of these branches, secretory vegetative (sympathetic) fibers also fit the gland. The lateral cutaneous branches of the second and third intercostal nerves are connected to the medial cutaneous nerve of the shoulder. These compounds are called the intercostal-brachial nerves (nn., Intercostobrachiales).

The anterior (ventral) cutaneous branches of the upper six intercostal nerves extend to the skin near the edge of the sternum, perforating the large pectoralis muscle. In the abdomen, the anterior branches of the seventh-twelfth intercostal nerves perforate the rectus abdominis muscle and the front sheet of its vagina and branch out into the skin above this muscle.

The anterior cutaneous branch of the subcostal nerve leaves subcutaneously just below the line drawn between the navel and the pubis. The anterior branches of II-IV intercostal nerves in women are called the medial branches of the mammary gland (r. Mammarii mediales), they give branches to the mammary gland.

The branches of the intercostal nerves innervate the rib and diaphragm parts of the pleura, the parietal peritoneum of the anterolateral wall of the abdominal cavity and the diaphragm.

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