The sternum (plural: sterna or sternums) completes the anterior chest wall as the ventral breastplate.

The sternum is composed of a manubrium, a body and the inferior xiphisternum (a.k.a. xiphoid process). They articulate via secondary cartilaginous joints via hyaline cartilage with a fibrocartilaginous intervening disc: 

  • the manubrium is flat and four-sided, wider superiorly
  • the body is a flat rectangular bone that has grooves (facets) on its lateral border for articulation with the ribs:
    • approximately 20 cm long
    • 3-4 cm wide
    • 1 cm thick
  • the xiphoid process is a thin bony projection inferiorly
  • superiorly the manubrium attaches to the neck where the two deep layers of cervical investing fascia insert
  • the manubrium articulates with the first rib (primary cartilaginous), clavicle (atypical synovial), and body of the sternum (secondary or primary cartilaginous joint) 6
  • the body articulates with the second rib at the sternomanubrial angle (of Louis , which is in the transthoracic plane of Ludwig) as well as the 3rd to 7th rib and costal cartilages
    • the articulations of 2nd and 7th ribs are shared as demifacets between each of the manubrium and the body, and the body and the xiphoid respectively 
  • inferiorly articulates with xiphisternal joint, a secondary cartilaginous joint 6 (symphysis)
  • nerve supply is via intercostal nerves which arise from the anterior rami of thoracic spinal nerves
Anatomy: Thoracic

Anatomy: Thoracic

Article information

rID: 46816
Section: Anatomy
Synonyms or Alternate Spellings:
  • Sternums
  • Sterna
  • Sternum (anatomy)
  • Breastbone

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Cases and figures

  • Figure 1a: sternum (Gray's illustration)
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  • Figure 1b: sternum (Gray's illustration)
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  • Figure 2a: thoracic cage (Gray's illustrations)
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  • Figure 4: sternal and costal cartilage muscular attachments (Gray's illustration)
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  • Figure 2b: thoracic cage (Gray's illustrations)
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  • Figure 3: costochondral joints (Gray's illustration)
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  • Case 1: tilted sternum
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