The flat T-shaped bone in the midline of the front of the chest to which the upper seven pairs of ribs attach
Sternum — the breastbone.
Anatomy · Bones
Sternum
The breastbone
Thorax · anterior chest
The sternum, or breastbone, is a flat, T-shaped bone in the midline of the front of the chest. It has three parts: the manubrium at the top, the long body and the small xiphoid process at the bottom. Seven pairs of ribs attach to it through their costal cartilages, and it helps protect the heart, lungs and oesophagus.
How to spot them
- ▸A flat, dagger- or tie-shaped bone in the midline of the front of the chest
- ▸Three parts: broad manubrium above, long body, and a small, often cartilaginous xiphoid process below
- ▸A U-shaped dip at the top, the jugular (suprasternal) notch, easily felt at the base of the neck
- ▸A transverse ridge where manubrium meets body, the angle of Louis, marking the second rib
What to know
A palpable transverse ridge where its upper two parts join marks the level of the second costal cartilage, and is used to count ribs
Sternum — the sternal angle, or angle of Louis, at the manubriosternal joint.
A shallow U-shaped notch at its upper border can be felt at the base of the neck; either side of it the clavicles articulate
Sternum — the jugular (suprasternal) notch and the clavicular notches.
Surgeons cut through this bone to reach the heart in open cardiac surgery
Sternum — median sternotomy.
Its top part is named for the Latin word for a handle, and its lowest tip from the Greek for a sword, as if the whole were a blade
Sternum — manubrium (Latin, handle) and xiphoid process (from Greek xiphos, sword).
Its lowest, smallest part is largely cartilage until around age 40, and its tip lies at the level of the tenth thoracic vertebra
Sternum — the xiphoid process.
In obese patients, it is used instead of the iliac crest as the site for bone marrow biopsy
Sternum — a source of red marrow.
Key ideas
- In children the three parts are joined by cartilage, which ossifies during adulthood.
- The sternum also helps to protect the heart and lungs; fractures need a violent blow and are associated with injuries to the heart and lungs.
Quick-fire facts
- •Three parts: manubrium, body and xiphoid process
- •Ribs 1 to 7 attach independently to the sternum, ribs 3 to 6 to the body and rib 1 to the manubrium
- •The manubrium articulates with the clavicles at the sternoclavicular joints
- •The manubriosternal joint (sternal angle, angle of Louis) marks the level of the second costal cartilage
- •The xiphisternal joint joins the body to the xiphoid process
- •Sternal fractures are uncommon; the commonest site is the manubriosternal joint
- •Pectus excavatum, or funnel chest, is a sunken sternum and adjoining ribs
- •The sternum is used for bone marrow biopsy where iliac crest access is limited
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Sources
- TeachMeAnatomy — The Sternum
- Kenhub — Sternum: Anatomy, parts, pain and diagram
- OpenStax — Anatomy and Physiology 2e, 7.4 The Thoracic Cage