The intercostal space (ICS) is the

anatomic space {{set index article In anatomy, a spatium or anatomic space is a space (cavity or gap). Anatomic spaces are often landmarks to find other important structures. When they fill with gases (such as air) or liquids (such as blood) in pathological ways, ...

between two

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi- ...

(Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.

Structures in intercostal space

* several kinds of

intercostal muscle Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size of ...

* intercostal arteries and intercostal veins * intercostal lymph nodes * intercostal nerves

Order of components

Muscles

There are 3 muscular layers in each intercostal space, consisting of the

external intercostal muscle The external intercostal muscles, or external intercostals (Intercostales externi) are eleven in number on both sides. Structure The muscles extend from the tubercles of the ribs behind, to the cartilages of the ribs in front, where they end ...

, the

internal intercostal muscle The internal intercostal muscles (intercostales interni) are a group of skeletal muscles located between the ribs. They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilage ...

, and the thinner innermost intercostal muscle. These muscles help to move the ribs during breathing.

Neurovascular bundles

Neurovascular bundles are located between the internal intercostal muscle and the innermost intercostal muscle. The neurovascular bundle has a strict order of

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenat ...

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

- nerve (VAN), from top to bottom. This neurovascular bundle runs high in the intercostal space, and the smaller collateral neurovascular bundle runs just superior to the lower rib of the space (in the order NAV from superior to inferior). Invasive procedures such as

thoracentesis Thoracentesis , also known as thoracocentesis (from Greek ''thōrax'' 'chest, thorax'—GEN ''thōrakos''—and ''kentēsis'' 'pricking, puncture'), pleural tap, needle thoracostomy, or needle decompression (often used term), is an invasive med ...

are performed with oblique entry of the instrument, directly above the upper margin of the relevant rib, to avoid damaging the neurovascular bundles.

Nerves

In reference to the muscles of the

thoracic wall The thoracic wall or chest wall is the boundary of the thoracic cavity. Structure The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely (from sup ...

, the intercostal nerves and vessels run just behind the internal intercostal muscles: therefore, they are generally covered on the inside by the parietal

pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips b ...

, except when they are covered by the innermost intercostal muscles, innermost intercostal membrane,

subcostal muscles Subcostal may refer to: * Subcostal nerve * Subcostal arteries The subcostal arteries, so named because they lie below the last ribs, constitute the lowest pair of branches derived from the thoracic aorta, and are in series with the intercostal a ...

or the

transversus thoracis muscle The transversus thoracis muscle (), also known as triangularis sterni, lies internal to the thoracic cage, anteriorly. It is usually a thin plane of muscular and tendinous fibers, however on athletic individuals it can be a thick 'slab of meat', ...

References

External links

* - "Structural organization within an intercostal space." * - "Thoracic Wall: The Anterior Thoracic Wall" Thorax (human anatomy) {{anatomy-stub