QS Study

Arch of aorta is the continuation of ascending aorta which begins at the manubriostemal joint (body of all vertebra) behind the upper border of the 2nd right sternchondral joint. It also ends at this level. The aorta distributes blood from the left ventricle of the heart to the rest of the body. It receives the cardiac output from the left ventricle and supplies the body with oxygenated blood via the systemic circulation.

Situation

It is situated in the superior mediastinum behind the lower half of manubrium stemi. Its location is in the superior mediastinum. Near the left side of T4 vertebra, at the very beginning, the arch is anteriorly located while at the termination it is posteriorly located.

Immediate relation

(A) Anteriorly & to the left:

(i) Nerves – from before backward:

  1. Left phrenic nerve.
  2. Lower cervical cardiac branch of left vagus.
  3. Upper cervical cardiac branch of the sympathetic chain.
  4. Left vagus nerve.

(ii) Left superior intercostal vein.

(iii) Left pleura & lung.

(iv) Remains of the thymus.

Fig: Arch of Aorta

(B) Posteriorly & to the right:

  • Trachea, deep cardiac plexus & tracheobronchial lymph nodes.
  • Oesophagus.
  • Left recurrent laryngeal nerve.
  • Thoracic duct.
  • Vertebral column.

(C) Superiorly: Branches of the aorta –

  • Brachiocephalic artery.
  • Left common carotid artery.
  • Left subclavian artery.

(D) Inferiorly:

  • Bifurcation of the pulmonary trunk.
  • Left principal bronchus.
  • Ligamentum arteriosum.
  • Left recurrent laryngeal nerve.

Branches

  • Brachiocephalic artery.
  • Left common carotid artery.
  • Left subclavian artery.

Occasionally

  • Arteria thyroid ima.
  • Left vertebral artery.
  • Inferior thyroid artery.
  • Internal thoracic artery.
  • Left bronchial artery.

Development

From –

1) Ventral part of an aortic sac.

2) Left horn of aortic sac.

3) Left 4th arch artery.

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