The thorax, known colloquially as breast, has inside a bone structure that forms and supports it, this structure is known as rib cage or chest bone.
The main elements of the rib cage are:
- The thoracic vertebrae dorsally.
- The side ribs.
- The sternum and rib cartilage to ensure the ribs to the sternum above.
The rib cage has a shape that resembles a cone briefly grows inferiorly as wide and form a hedge whose main functions are:
- Protect the vital organs of the chest cavity as the heart, lungs and major blood vessels.
- Supports the shoulder girdle and upper extremities.
- Provides the anchors of many muscles of the neck, back, chest and shoulders.
- Finally the intercostals space (between ribs) is occupied by the intercostals muscles that lift and depress the chest during breathing.
Structure rib cage
Let’s use some characteristics of the main components of the rib cage.
Lies in the anterior mid line of the chest with a shape that vaguely resembles a dagger.It is a flat bone about 15 cm long and has been the result of the fusion of three bones:
- The handlebars: which is the upper portion recalls the knot of a tie and articulates with the clavicles by means of clavicular notches. It also articulates with the top two first ribs.
- The body: is the middle portion and forms most of the mass of the sternum. Their lateral zones have notches where articulated ribs from the second to the seventh.
- xiphoid process: it is the lower end of the sternum, is small, varying in shape, and consists of hyaline cartilage during childhood and youth, but usually ossified in adults. This processes only articulates with the body of the sternum and serves as an anchor of some abs +.
The sternum has three points of anatomical interest:
1.-The jugular notch: also known as sternal notch is a central slit in the top of the handle. It is easily palpated and is generally aligned with the inter vertebral disk between the second and third thoracic vertebrae and the point where the left common carotid artery leaving the aorta.
- The external angle: you can feel as a horizontal ridge crossing the sternum in the area where the handle meets the body and is a cartilaginous union that functions as a hinge allowing the body to “pivot” about the handlebars when it was inspired during breathing. The Outer Edge is located in line with the inter vertebral disc that lies between the fourth and fifth thoracic vertebra and at the level of the second pair of ribs and is a good benchmark to detect this pair when the ribs are counted.
- The joint xiphisternal: is the point where the xiphoid process of the sternum and body melt and lies opposite the ninth thoracic vertebra.
Forming the sides of the rib cage are 12 pairs, all anchored to bodies and the transverse processes of the thoracic vertebrae, and are bent downwardly toward the front body surface. The first 7 pairs are anchored directly above the sternum through independent costal cartilages (hyaline cartilage rods giving a secure but flexible link) and therefore are called true ribs (Figure 1). The remaining 5 pairs (8-12) are not anchored directly to the sternum, or do so indirectly (8-10) or have no connection to the sternum (11 and 12) and thus are called together ribs false. Among the false ribs, the last 2 pairs (11 and 12) do not have any previous attachment to the sternum and this makes floating ribs. Note that pairs of 8 to 10 are integral with the sternum through the costal cartilage junction with the next higher rib. In the floating ribs their costal cartilages lie embedded in the muscles of the body side walls.
The length of the ribs increases the pair 1 to pair 7 and thereafter the length of the pairs decreases from 8 to 12.
The typical true rib
It is a bent flat bone and its main portion is called the body, the upper edge of the body is smooth, but its lower edge is sharp and thin and has on its inner face a rib groove, which is the cause through which flow nerves and intercostals vessels. The forward end of the body is anchored to the rib cartilage securing it to the sternum.
In the general structure of the rib can differentiate certain significant parts are:
- Head: is the rear end of the rib and has two facet joints, one articulates with the body of thoracic vertebra of the same number and the other with the body of the vertebra immediately above.
- Neck: a constrained rib which is just below the head area.
- Tuber: lies laterally on the neck and articulates with the transverse process of the thoracic vertebra of the same number.
- Angle: is the area of the body below the rib neck that curves sharply forward.
Particularidas certain ribs
- Primer pair: is remarkably atypical, ribs of this pair are flattened in the upper-lower direction and are also wide enough to form a horizontal table supporting subclavian blood vessels serving the upper extremities.
- Pairs 10 to 12: show the distinctive feature of which articulate only the body of a vertebra.
- Pairs 11 and 12: they differ in that they do not articulate with the vertebral transverse process.