Arch of aorta

Description of the arch of the aorta and its relations along with few genetic manformatins

1. ARCH OF AORTA

2. ARCH OF AORTA Continuation of the ascending aorta Situated in the superior mediastinum, behind manubrium sterni Arches over the root of left lung Continues as the descending aorta Begins and ends at the same level

3. COURSE Begins behind the upper border of 2 nd Right sternochondral joint Runs upwards, backwards and to the left across the left side of the bifurcation of trachea Passes downwards behind the left bronchus and on the left side of the body of 4 th thoracic vertebra Arches the root of the left lung Ends at the lower border of 4 th thoracic vertebra

4. RELATIONS Anteriorly and to the left Four nerves (from before backwards) Left phrenic Lower cervical cardiac branch of left vagus Superior cervical cardiac branch of sympathetic chain Left vagus Left superior intercostal vein, deep to phenic nerve and superficial to vagus Left lung and its pleura Remains of thymus

5. B. Posteriorly and to the right Trachea with the deep cardiac plexus and the tracheobronchial lymph nodes Oesophagus Left recurrent laryngeal nerve Thoracic duct Vertebral column

6. C. Superior Branches of arch of aorta Brachiocephalic trunk Left common carotid Left subclavian All these are crossed by the left brachiocephalic vein, close to their origin

7. D. Inferior Bifuraction of pulmonary trunk Left bronchus Ligamentum arteriosum with superficial cardiac plexus on it Left recurrent laryngeal nerve

8. BRANCHES MAIN BRANCHES Brachiocephalic trunk Left common caritid Left subclavian OCCASIONAL BRANCHES Left vertebral artery Arteria thyroidea ima Inferior thyroid artery Internal thoracic artery Left bronchial artery Right subclavian artery

9. DEVELOPMENT Three major sources of development Left limb of the aortic sac ( truncus arteriosus) Forms the part between the brachiocephalic trunk and the left common carotid artery Left fourth aortic arch Forms the part between left common carotid and left subclavian artery Left dorsal aortic arch Forms the rest of the arch of aorta up to the descending aorta

10. DEVELOPMENTAL ANOMALIES Right sided aortic arch Due to persistence of right dorsal aorta below the 7 th intersegmental artery Disappearance of left dorsal aorta Common in birds Double aortic arch Due to persistence of both the aortic arches

11. 3. Origin of Right subclavian artery from the junction of aortic arch and descending aorta Due to persistance of right dorsal aorta below 7 th intersegmental artery and Disappearance of fourth aortic arch Coarctation of aorta Due to stenosis or atresia of arch of aorta distal to the origin of left subclavian artery May be of Preductal – ductus arteriosus remains patent Postductal – ductus arteriosus is obliterated

12. Coarctation of aorta Double aortic arch Right subclavian artery