The intercostal spaces

There are slight variations between the different intercostal spaces, but typically each space contains three muscles, comparable to those of the abdominal wall, and an associated neurovascular bundle (Fig. 8). The muscles are:

Subcostal Neurovascular Bundle

Intercostal

.Vein

-Artery

.Nerve

Intercostal

Fig. 8 The relationship of an intercostal space. (Note that a needle passed into the chest immediately above a rib will avoid the neurovascular bundle.)

1 the external intercostal, the fibres of which pass downwards and forwards from the rib above to the rib below and reach from the vertebrae behind to the costochondral junction in front, where muscle is replaced by the anterior intercostal membrane;

2 the internal intercostal, which runs downwards and backwards from the sternum to the angles of the ribs where it becomes the posterior intercostal membrane;

3 the innermost intercostal, which is only incompletely separated from the internal intercostal muscle by the neurovascular bundle.

The fibres of this sheet cross more than one intercostal space and it may be incomplete. Anteriorly it has a more distinct portion which is fan-like in shape, termed the transversus thoracis (or sternocostalis), which spreads upwards from the posterior aspect of the lower sternum to insert onto the inner surfaces of the second to the sixth costal cartilages.

Just as in the abdomen, the nerves and vessels of the thoracic wall lie between the middle and innermost layers of muscles. This neurovascular bundle consists, from above downwards, of vein, artery and nerve, the vein lying in a groove on the undersurface of the corresponding rib (remember— v,a,n).

The vessels comprise the posterior and anterior intercostals.

The posterior intercostal arteries of the lower nine spaces are branches of the thoracic aorta, while the first two are derived from the superior intercostal branch of the costocervical trunk, the only branch of the second part of the subclavian artery. Each runs forward in the subcostal groove to anastomose with the anterior intercostal artery. Each has a number of branches to adjacent muscles, to the skin and to the spinal cord. The corresponding veins are mostly tributaries of the azygos and hemiazygos veins. The first posterior intercostal vein drains into the brachiocephalic or vertebral vein.

Posterior primary ramus

Lateral cutaneous branch

Anterior cutaneous branch

Intercostal Nerve Diagram

Sites at which pus from a tuberculous vertebra tends to point

Fig. 9 Diagram of a typical spinal nerve and its body-wall relationships. On the left side the sites of eruption of a tuberculous cold abscess tracking forwards from a diseased vertebra are shown—these occur at the points of emergence of the cutaneous branches.

Anterior primary ramus

Lateral cutaneous branch

Sites at which pus from a tuberculous vertebra tends to point

Anterior cutaneous branch

Fig. 9 Diagram of a typical spinal nerve and its body-wall relationships. On the left side the sites of eruption of a tuberculous cold abscess tracking forwards from a diseased vertebra are shown—these occur at the points of emergence of the cutaneous branches.

On the left, the 2nd and 3rd veins often join to form a superior intercostal vein, which crosses the aortic arch to drain into the left brachiocephalic vein.

The anterior intercostal arteries are branches of the internal thoracic artery (1st-6th space) or of its musculophrenic branch (7th-9th spaces). The lowest two spaces have only posterior arteries. Perforating branches pierce the upper five or six intercostal spaces; those of the 2nd-4th spaces are large in the female and supply the breast.

The intercostal nerves are the anterior primary rami of the thoracic nerves, each of which gives off a collateral muscular branch and lateral and anterior cutaneous branches for the innervation of the thoracic and abdominal walls (Fig. 9).

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Responses

  • walter murphy
    Where is the neurovascular bundle located on rib?
    8 years ago
  • marisol chandler
    Is intercostal space above or below rib?
    7 years ago
  • nea
    Where does the neurovascular bundle in ribs lie?
    6 years ago
  • linda
    Are intercostal spaces above or below the rib?
    6 years ago
  • Medhanit
    Is the 4th intracoastal space above or below the 4th rib?
    6 years ago
  • lexi
    Where is the intercostal nerve, artery, and vein (neurovascular bundle) located?
    5 years ago
  • selam
    Do intercostal nerves run in a neurovascular bundle?
    5 years ago
  • Yerusalem
    Is intercostal space measured below rib?
    5 years ago
  • zahra
    Is intercostal space named for the rib above or below?
    4 years ago
  • gisella
    What are the cure for intercostal space definition?
    3 years ago
  • sara
    Is the 1st intrcoastal space located above or below the first rib?
    2 years ago
  • zofia
    Where is the neurovascular bundle located in ribs?
    6 months ago

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