17. Thoracic wall

17. Thoracic wall

There are 12 thoracic vertebrae. Each rib articulates with the body of the numerically corresponding vertebra and the one below it. Sternum: the manubrium articulates with the clavicle and the first rib. It meets the body of the sternum at the sternal angel an important clinical landmark.

The body articulates directly with ribs 2–7; it articulates interiorly with the xiphoid process.

Ribs and costal cartilages: there are 12 pairs of ribs, which are attached posteriorly to thoracic vertebrae.

Ribs 1–7 attach directly to the sternum by costal cartilages.

Ribs 8 – 10 attach to the costal cartilage of the rib above. Ribs 11 and 12 have no anterior attachments. The costal groove is located along the inferior border of each rib and provides protection for the intercostal nerve artery, and vein.

There are 11 pairs of external intercostal muscles.

These muscles fill the intercostal spaces from the tubercles of ribs posteriorly to the costochondral junctions anteriorly. There are 11 pairs of internal intercostal muscles.

These muscles fill the intercostal spaces anteriorly from the sternum to the angles of the ribs posteriorly.

Innermost intercostal muscles: the deep layers of the internal intercostal muscles are the innermost intercostal muscles.

Subcostalis portion: Fibers extend from the inner surface of the angle of one rib to the rib that is inferior to it.

Internal thoracic vessels, branches of the subclavian arteries, run anterior to these fibers. Intercostal structures

Intercostal nerves: there are 12 pairs of thoracic nerves, 11 intercostal pairs, and 1 subcostal pair.

Intercostal nerves are the ventral primary rami of thoracic spinal nerves. These nerves supply the skin and musculature of the thoracic and abdominal walls.

Intercostal arteries: there are 12 pairs of posterior and anterior arteries, 11 intercostal pairs, and 1 subcostal pair.

Anterior intercostal arteries.

Pairs 1–6 are derived from the internal thoracic arteries.

Pairs 7–9 are derived from the musculophrenic arteries.

Posterior intercostal arteries: the first two pairs arise from the superior intercostal artery, a branch of the costo-cervical trunk of the subcla vian artery.

Nine pairs of intercostal and one pair of subcostal arter ies arise from the thoracic aorta.

Intercostal veins: Anterior branches of the intercostal veins drain to the internal thoracic and musculophrenic veins.

Posterior branches drain to the azygos system of veins.

Lymphatic drainage of intercostal spaces: anterior drainage is to the internal thoracic (parasternal) nodes.

Posterior drainage is to the paraaortic nodes of the poste rior mediastinum.

New words

thoracic – грудной

wall – стенка

clavicle – ключица

xiphisternal – грудинный

groove – углубление

intercostal – межреберный

subcostal – подкостный

transversus – поперечный

musculophrenic – мышечный грудобрюшной

paraaortic – парааортальный

mediastinum – средостение