aortic arches

Examples of aortic arches in the following topics:

• Arch of the Aorta

  • The arch of the aorta follows the ascending aorta and begins at the level of the second sternocostal articulation of the right side.
  • The arch of the aorta, or the transverse aortic arch, is continuous with the upper border of the ascending aorta and begins at the level of the upper border of the second sternocostal articulation of the right side.
  • Three vessels come out of the aortic arch: the brachiocephalic artery, the left common carotid artery, and the left subclavian artery.
  • In approximately 20% of individuals, the left common carotid artery arises from the brachiocephalic artery rather than the aortic arch, and in approximately 7% of individuals the left subclavian artery also arises here.
  • This diagram shows the arch of the aorta and its branches.

• Development of the Heart

  • While the arterial system develops mainly from the aortic arches, the venous system arises from three bilateral veins during weeks four through eight of human development.
  • The human arterial system originates from the aortic arches and from the dorsal aortae starting from week four of human development.
  • Aortic arch 1 almost completely regresses except to form the maxillary arteries.
  • Aortic arch 2 also completely regresses except to form the stapedial arteries.
  • The definitive formation of the arterial system arise from aortic arches 3, 4 and 6, while aortic arch 5 completely regresses.

• Development of the Cardiovascular System

  • The human arterial system originates from the aortic arches and from the dorsal aortae starting from week 4 of embryonic life.
  • The aortic arches—or pharyngeal arch arteries—are a series of six, paired, embryological vascular structures that give rise to several major arteries .
  • The third aortic arch constitutes the commencement of the internal carotid artery, and is named the carotid arch.
  • Clinical Example: Most defects of the great arteries arise as a result of the persistence of aortic arches that normally should regress or due to the regression of arches that normally should not.
  • A double aortic arch occurs with the development of an abnormal right aortic arch, in addition to the left aortic arch, forming a vascular ring around the trachea and esophagus, which usually causes difficulty breathing and swallowing.

• Veins of the Head and Neck

  • In the head and neck, blood circulates from the upper systemic loop, which originates at the aortic arch.

• Thoracic Aorta

  • The thoracic aorta forms part of the descending aorta and is continuous with the aortic arch at its origin before becoming the abdominal aorta.
  • Contained within the posterior mediastinal cavity, it begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra at the aortic hiatus in the diaphragm.

• Ascending Aorta

  • The ascending aorta is the first portion of the aorta; it includes the aortic sinuses, the bulb of the aorta, and the sinotubular junction.
  • The aortic root is the portion of the ascending aorta beginning at the aortic annulus, the fibrous attachment between the heart and the aorta, and extending to the sinotubular junction.
  • Just above the aortic valve are three small dilations called the aortic sinuses.
  • At the junction of the ascending aorta with the aortic arch, the caliber of the vessel increases with a bulging of its right wall.
  • The aorta has three parts: the ascending, the arch and the descending.

• Great Vessels of the Heart

  • Blood is pumped from the left ventricle through the aortic valve into the aorta.
  • When the left ventricle contracts to force blood through the aortic valve into the aorta, the aorta expands.
  • The aortic arch contains peripheral baroreceptors (pressure sensors) and chemoreceptors (chemical sensors) that relay information concerning blood pressure, blood pH, and carbon dioxide levels to the medulla oblongata of the brain.
  • The ascending aorta lies between the heart and the arch of aorta.
  • It breaks off into the aortic sinuses, some of which form the coronary arteries.

• Systemic and Pulmonary Circulation

  • From the left ventricle, the blood is pumped through the aortic valve into the aorta to travel through systemic circulation, delivering oxygenated blood to the body before returning again to the pulmonary circulation.
  • From the left ventricle, blood is pumped through the aortic valve and into the aorta, the body's largest artery.
  • The aorta arches and branches into major arteries to the upper body before passing through the diaphragm, where it branches further into arteries which supply the lower parts of the body.

• Autonomic Plexuses

  • The autonomic plexuses include the cardiac plexus, the pulmonary plexus, the esophageal plexus, and abdominal aortic plexus, and the superior and inferior hypogastric plexuses.
  • The superficial part of the cardiac plexus lies beneath the arch of the aorta, in front of the right pulmonary artery.
  • The abdominal aortic plexus is formed by branches derived, on either side, from the celiac plexus and ganglia, and receives filaments from some of the lumbar ganglia.

• Operation of Semilunar Valves

  • The aortic valve separates the left ventricle from the aorta and has three cusps .
  • When the pressure in the left ventricle exceeds the pressure in the aorta, the aortic valve opens, and blood flows from the left ventricle into the aorta.
  • When ventricular systole ends, pressure in the left ventricle drops rapidly, and the aortic pressure forces the aortic valve to close.
  • This anterior view of the heart indicates the semilunar valves, the aortic and pulmonary valves.
  • Describe the operation of the semilunar valves, the aortic and pulmonary valves