Editing Vascular system (section)

== '''Thoracic aorta''' ==

* Surface markings
** Arch begins at second right      costal cartilage and ends at second left costal cartilage, and reaches up      as far as mid-manubrium
** Descending aorta starts at      second left costal cartilage, and ends in midline at about xiphisternum
* Ascending aorta
** Emerges pericardium, ends at      the level of manubriosternal joint where it becomes the arch
* Aortic arch
** Upper convexity reaches as      high as the midpoint of the manubrium
** Branches
*** Brachiocephalic trunk
**** Arises from arch about 2cm        below sternal notch
**** Divides behind right SCJ        into right subclavian and right common carotid
**** Can sometimes have the        thyroid ima as a branch
*** Left common carotid
*** Subclavian
* Descending thoracic aorta
** Commences at the lower      border of T4. At first just to left of midline, but slants medially to so      that the diaphragmatic hiatus is in the midline.
** Branches:
*** 9 posterior intercostal       arteries
*** Bronchial arteries
*** Some small oesophageal       vessels
*** Be aware of arteria       radicularis magna - a larger intercostal or lumbar artery supplying cord       segments, which can lead to paraplegia if clamped excessively
* Variants
** Brachiocephalic artery and      left CCA can arise as a single trunk
** Double aortic arch - early      obstructive symptoms
** Aberrant right subclavian      artery - arteria lusoria - 1%
*** Passes posterior to       oesophagus and can cause compressive symptoms