There are 11 pairs of external intercostal muscles. Their fibers run anteriorly and inferiorly in the intercostal spaces from the rib above to the rib below.

These muscles fill the intercostal spaces from the tubercles of ribs posteriorly to the costochondral junctions anteriorly; they are replaced anteriorly by external intercostal membranes. Internal intercostal muscles: there are 11 pairs of internal intercostal muscles. Their fibers run posteriorly and inferiorly in the intercostal spaces deep to the external layer.

These muscles fill the intercostal spaces anteriorly from the sternum to the angles of the ribs posteriorly; they are replaced posteriorly by internal intercostal membranes.

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

These muscles are separated from the internal intercostal muscles by intercostal nerves and vessels.

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

Fibers may cross more than one intercostal space, Transversus tho-racis portion: Fibers attach posteriorly to the sternum. Fibers cross more than one intercostal space.

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.

There are no anterior intercostal arteries in the last two spaces; these spaces are supplied by branches of the pos terior intercostal arteries.

Posterior intercostal arteries: the first two pairs arise from the superior intercostal artery, a branch of the costocervical 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

below – под

sternum – грудина

clavicle – ключица

xiphisternal – грудинный

true – правдивый

false – фальшивый

groove – углубление

above – над

anteriorly – раньше

intercostal – межреберный

subcostal – подкостный

portion – часть

transversus – поперечный

musculophrenic – мышечный грудобрюшной

paraaortic – парааортальный

mediastinum – средостение

Запомните следующее застывшее словосочетание.