Episternal ossicles
Episternal (or suprasternal) ossicles are accessory bones and a normal variant of the sternum. They result from supernumerary ossification centers and are seen in ~4% (range 1-7%) of the population.
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Gross anatomy
Episternal ossicles are usually located posterior or superior to the superior border of the manubrium and may be unilateral or bilateral. They range in diameter from 2-15 mm and are located in a retro- or supra-manubrial location.
In three dimensions, they are quadrilateral pyramids whose bases articulate with the manubrium. The apices point medially, but rounding of the corners may mask this appearance.
Radiographic features
Their visualization using radiographs can be difficult but with the use of computed tomography are clearly identifiable, revealing unilateral or bilateral triangular ossicles in a retro- or supra-manubrial location.
Differential diagnosis
- parasternal ossicles: within the 1st costal cartilage
It is also important to differentiate them from:
- calcified lymph nodes
- fracture fragments
- vascular calcifications
- foreign bodies
- osteophytes
Related Radiopaedia articles
Anatomy: Thoracic
- thoracic skeleton
- thoracic cage
- thoracic spine
- articulations
- muscles of the thorax
- diaphragm
- intercostal space
- intercostal muscles
- variant anatomy
- spaces of the thorax
- thoracic viscera
- tracheobronchial tree
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lungs
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
- left lung
- right lung
- variant anatomy
- lung parenchyma
- hilum
- pleura
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
-
heart
- cardiac chambers
- heart valves
- pectinate muscles
- cardiac fibrous skeleton
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coronary arteries
- coronary arterial dominance
- myocardial segments
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left main coronary artery (LMCA)
- ramus intermedius artery (RI)
-
circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
- Kugel's artery
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left anterior descending artery (LAD)
- diagonal branches (D1, D2, etc)
- septal perforators (S1, S2, etc)
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right coronary artery (RCA)
- conus artery
- sinoatrial nodal artery
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- inferior interventricular artery (PDA)
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- congenital anomalies
- innervation of the heart
- fetal circulation
- atrial septum
- endocardium
- myocardium
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pericardium
- epicardium
- epicardial fat pad
- pericardial space
- oblique pericardial sinus
- transverse pericardial sinus
-
pericardial recesses
- aortic recesses
- pulmonic recesses
- postcaval recess
- pulmonary venous recesses
- pericardial ligaments
- esophagus
- thymus
- breast
- blood supply of the thorax
- arteries
- veins
- superior vena cava (SVC)
- inferior vena cava (IVC)
-
coronary veins
- cardiac veins which drain into the coronary sinus
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior vein of the left ventricle
- vein of Marshall (oblique vein of the left atrium)
- anterior cardiac veins
- venae cordis minimae (smallest cardiac veins or thebesian veins)
- cardiac veins which drain into the coronary sinus
- pulmonary veins
- thoracoepigastric vein
- lymphatics
- innervation of the thorax
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