Sternum

The sternum (pl.: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Shaped roughly like a necktie, it is one of the largest and longest flat bones of the body. Its three regions are the manubrium, the body, and the xiphoid process.^[1] The word sternum originates from Ancient Greek στέρνον (stérnon) 'chest'.

Sternum

sternum

Manubrium

Body (gladiolus)

Xiphoid process

Clinical significance[edit]

Bone marrow biopsy[edit]

Because the sternum contains bone marrow, it is sometimes used as a site for bone marrow biopsy. In particular, patients with a high BMI (obese or grossly overweight) may present with excess tissue that makes access to traditional marrow biopsy sites such as the pelvis difficult.

Sternal opening[edit]

A somewhat rare congenital disorder of the sternum sometimes referred to as an anatomical variation is a sternal foramen, a single round hole in the sternum that is present from birth and usually is off-centered to the right or left, commonly forming in the 2nd, 3rd, and 4th segments of the breastbone body. Congenital sternal foramina can often be mistaken for bullet holes.^[11] They are usually without symptoms but can be problematic if acupuncture in the area is intended.^[12]

Etymology[edit]

English sternum is a translation of Ancient Greek στέρνον, sternon.^[18] The Greek writer Homer used the term στέρνον to refer to the male chest,^[19]^[20] and the term στῆθος, stithos to refer to the chest of both sexes.^[19]^[20] The Greek physician Hippocrates used στέρνον to refer to the chest,^[19]^[20] and στῆθος to the breastbone.^[19]^[20] The Greek physician Galen was the first to use στέρνον in the present meaning of breastbone.^[19]^[20]

The sternum as the solid bony part of the chest^[21] can be related to Ancient Greek στερεός/στερρός, (stereόs/sterrόs),^[21] meaning firm or solid.^[20] The English term breastbone is actually more like the Latin os pectoris,^[22]^[23] derived from classical Latin os, bone^[24] and pectus, chest or breast.^[24] Confusingly, pectus is also used in classical Latin as breastbone.^[24]