aortic sinuses

Examples of aortic sinuses in the following topics:

• 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.
  • The two anterior sinuses give rise to the coronary arteries, while the third posterior sinus does not usually give rise to any vessels and so is known as the non-coronary sinus.
  • The sinotubular junction is the point in the ascending aorta where the aortic sinuses end and the aorta becomes a tubular structure.

• Short-Term Neural Control

  • Vascular baroreceptors are found primarily in sinuses (small cavities) within the aorta and carotid arteries.
  • The aortic sinuses are found in the walls of the ascending aorta just superior to the aortic valve, whereas the carotid sinuses are located in the base of the internal carotid arteries.

• 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.
  • It breaks off into the aortic sinuses, some of which form the coronary arteries.

• Venous Blood Pressure

  • Fainting can occur, but usually baroreceptors within the aortic sinuses initiate a baroreflex, triggering angiotensin II and norepinephrine release and consequent vasoconstriction and heart rate increases to augment blood flow return.

• Veins of the Head and Neck

  • In the head and neck, blood circulates from the upper systemic loop, which originates at the aortic arch.
  • The deep-lying internal jugular vein receives blood from the dural venous sinuses in the brain as well as the cerebral and cerebellar veins.
  • Dural sinuses are composed of dural mater lined with endothelium, making them distinct from arteries, veins, and capillaries.
  • The dural sinuses receive blood from the veins that drain the brain and skull.

• Paranasal Sinuses

  • Paranasal sinuses are a group of four, paired, air-filled spaces that surround the nasal cavity (maxillary sinuses), above the eyes (frontal sinuses), between the eyes (ethmoid sinuses), and behind the eyes (sphenoid sinuses).
  • The sinuses are named for the facial bones that they are located behind.
  • The maxillary sinuses (also called the maxillary antrechea, the largest of the paranasal sinuses) are located under the orbits in the maxillary bones.
  • The frontal sinuses are superior to the orbits and are in the frontal bone.
  • This image shows the position of the sinuses in the human skull.

• Sinusitis

  • Sinusitis, the inflammation of the paranasal sinuses, is a very common condition in the US with potentially dangerous complications.
  • Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues.
  • Viral sinusitis typically lasts for 7 to 10 days, whereas bacterial sinusitis is more persistent.
  • Acute episodes of sinusitis can also result from fungal invasion.
  • Chronic sinusitis lasts longer than three months and can be caused by many different diseases that share chronic inflammation of the sinuses as a common symptom.

• Nose and Paranasal Sinuses

  • The nose and paranasal sinuses form much of the upper respiratory tract, along with the pharynx.
  • The paranasal sinuses are a group of four, paired, air-filled spaces, lined with respiratory epithelium (ciliated columnar epithelium).
  • These are named according to the bones within which the sinuses lie: surrounding the nasal cavity (maxillary sinuses), above the eyes (frontal sinuses), between the eyes (ethmoid sinuses), and behind the ethmoid bone (sphenoid sinuses).
  • The functions of the sinuses are not fully understood, but there are many possible functions.
  • The most important function is the sinuses' role in draining mucus from the nasal cavity to the nasopharynx, which helps regulate pressure inside the nasal cavity.

• 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

• 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.