The sternum is one elongated, planarization bone. Shaped prefer a funding T, the sternum creates the middle section of the anterior wall of the thorax, which help to defend the lungs, heart and major blood vessels from physical trauma. The upper finish of the sternum supports the clavicles.

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The superior 7 costal cartilages articulate with the sternum, creating the costal margin anteriorly. The right and also left clavicular notches articulate through the right and also left clavicles, respectively. The costal cartilage that the 2nd rib articulates with the sternum at the sternal angle, make it basic to locate.\

Figure 1. Thoracic cage, showing ar of sternum and also ribs

Muscle and ligament attachments

The transversus thoracis muscle is innervated through the intercostal nerve and also superiorly attaches at the posterior surface of the reduced sternum. Its worse attachment is the internal surface the costal cartilages two with six and also works to boring the ribs.

The upper end of the sternum connects come the sternocleidomastoid muscle.

Surface anatomy

 The sternum consists of 3 parts, provided superior to inferior:

Manubrium, the wide superior part of the sternum. The suprasternal (jugular) notch is medially located at the superior finish of the manubrium. Located superiorly and also laterally are the right and also left clavicular notches.Xiphoid process, situated at the inferior finish of the sternum. Improperly perform chest compressions during cardiopulmonary resuscitation can cause the xiphoid procedure to snap off, driving it right into the liver, i beg your pardon can cause a deadly hemorrhage.

Figure 1. Posterior surface of the sternum

In its natural position, the inclination that the sternum is oblique native above, downward and forward. The sternum is slightly convex in front and concave behind. It is broad above, coming to be narrowed in ~ the suggest where the manubrium join the body, ~ which the again widens a little to listed below the center of the body, and also then narrows to its reduced extremity. The average length of the sternum in one adult is around 17 cm; the is much longer in the male than in the female.

In early life, the body of the sternum is separated in 3 segments, dubbed sternebrœ.

The sternum is created of very vascular tissue, extended by a slim layer of compact bone i beg your pardon is thickest in the manubrium between the articular facets because that the clavicles.


Physical examination



A somewhat rare congenital problem of the sternum is a sternal foramen, a single round hole in the sternum the is current from birth and also usually is off-centered to the appropriate or left, commonly forming in the 2nd, 3rd, and fourth segments the the sternum body. Sternal foramens can frequently be mistake for bullet holes.

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Fractures that the sternum are rather uncommon. Castle may result from trauma, together as once a driver"s chest is compelled into the steering obelisk of a vehicle in a vehicle accident or from repeated punches or consistent beatings come the sternum area. Sternum fractures are frequently associated with basic injuries such as pulmonary contusions.

A fracture that the sternum is typically a comminuted fracture. The most common site of sternal fractures is in ~ the sternal angle.