Expansion
A third pharyngeal pouch derivative lying in the anterior and superior mediastinum
Expansion
- Origin - the ventral wing of the third pharyngeal pouch, descending into the thorax
- Position - anterior and superior mediastinum, behind the manubrium and in front of the great vessels
- Blood supply - internal thoracic and inferior thyroid arteries
- Fate - largest at puberty, then progressively replaced by fat
In children a normal thymus produces the sail sign on a chest radiograph and should not be mistaken for a mass. In adults, thymic enlargement is abnormal and raises the possibility of thymoma, which carries a well-known association with myasthenia gravis and with red cell aplasia.