vena cava

Examples of vena cava in the following topics:

• Great Vessels of the Heart

  • The superior vena cava and inferior vena cava are collectively called the venae cavae.
  • The venae cavae are not separated from the right atrium by valves.
  • The venae cavae, along with the aorta, are the great vessels involved in systemic circulation.
  • The superior vena cava begins above the heart.
  • The left and right common iliac veins converge to form the inferior vena cava at its lowest point.

• Veins of the Thorax

  • Two venae cavae return deoxygenated blood from the systemic circulation to the right atrium of the heart.
  • The superior vena cava returns deoxgenated blood from the upper half of the body and is formed from the left and right brachiocephalic veins of the upper carrying blood from the upper limbs and also blood from the head and neck via the thyroid and jugular veins.
  • The inferior vena cava returns blood from the abdomen and lower limbs to the right atrium of the heart.
  • The renal veins from the kidney and hepatic veins of the liver drain directly into the inferior vena cava.
  • Additionally, the superior and inferior phrenic veins drain the diaphragm and usually open into the internal mammary vein and inferior vena cava, respectively.

• Principal Veins

  • The venae cavae are the largest diameter veins in the body.
  • Both enter the right atrium of the heart with the superior vena cava carrying blood from the arms, head and thoracic cavity and the inderior vena cava carrying blood from the legs and abdomen.
  • The inferior vena cava runs parallel to the abdominal aorta.
  • The superior vena cava is formed from the brachiocephalic veins which are in turn formed from the subclavian and internal jugular veins which serve the arm and head respectively.
  • The inferior vena cava is formed from the common  iliac veins which serve the legs and abdomen, the renal and heaptic veins from the kidneys and liver respectively also feed into the inferior vena cava.

• Supply of Blood and Nerves to the Kidneys

  • Due to the position of the aorta, the inferior vena cava, and the kidneys in the body, the right renal artery is normally longer than the left renal artery.
  • Renal blood supply starts with the branching of the aorta into the renal arteries (which are each named based on the region of the kidney they pass through) and ends with the exiting of the renal veins to join the inferior vena cava.
  • The renal veins are the veins that drain the kidneys and connect them to the inferior vena cava.

• Veins of the Abdomen and Pelvis

  • The left and right common iliac veins come together in the abdomen at the level of the fifth lumbar vertebra, forming the abdominal vena cava.
  • The deep circumflex iliac vein is formed by the union of the venae comitantes of the deep iliac circumflex artery, and joins the external iliac vein about 2 cm above the inguinal ligament.
  • The veins of the abdomen and lower limb include the inferior vena cava, the common iliac veins, the external iliac veins, and their tributaries.

• Blood Supply to the Lungs

  • At the end of systemic circulation, the veins take blood back to the heart through the vena cava.
  • The vena cava fills the right atrium with blood, which then ejects blood into the right ventricle by passing through the tricuspid valve.

• Systemic and Pulmonary Circulation

  • Oxygen-depleted blood from the body leaves the systemic circulation when it enters the right atrium through the superior and inferior venae cavae.
  • The deoxygenated blood continues through the capillaries which merge into venules, then veins, and finally the venae cavae, which drain into the right atrium of the heart.

• Short-Term Neural Control

  • There are also low-pressure baroreceptors located in the walls of the venae cavae and right atrium.
  • The baroreceptors in the venae cavae and right atrium monitor blood pressure as the blood returns to the heart from the systemic circulation.

• Abdominal Aorta

  • The abdominal aorta runs parallel to the inferior vena cava, which is located just to the right of the abdominal aorta.

• Blood Flow Through the Body

  • After the blood has passed through the capillary beds, it enters the venules, veins, and finally the two main venae cavae (singular, vena cava) that take blood back to the heart.
  • Blood leaves the heart through the pulmonary artery and aorta, while blood enters the heart through the two venae cavae and pulmonary veins.