superior vena cava

Examples of superior vena cava in the following topics:

• Great Vessels of the Heart

  • The superior and inferior vena cava are collectively called the venae cavae.
  • The superior vena cava is a large, short vein that carries deoxygenated blood from the upper half of the body to the right atrium.
  • The right and left subclavian veins, jugular veins, and thyroid veins feed into the superior vena cava.
  • The superior vena cava begins above the heart.
  • The right pulmonary veins pass behind the right atrium and superior vena cava while the left pass in front of the descending thoracic aorta.

• 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, formed from the left and right brachiocephalic veins, returns deoxygenated blood from the upper half of the body and carries blood from the upper limbs, 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 veins with the largest diameter.
  • Both enter the right atrium of the heart with the superior vena cava carrying blood from the arms, head, and thoracic cavity and the inferior 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 that serve the arm and head respectively.
  • The inferior vena cava is formed from the common iliac veins that serve the legs and abdomen.

• Structures of the Heart

  • The right atrium receives deoxygenated blood from the superior vena cava, which drains blood from the veins of the upper organs and arms.
  • The right atrium also receives blood from the inferior vena cava, which drains blood from the veins of the lower organs and legs.

• Directional Terms

  • Superior and inferior (cranial and caudal) are used when referring to parts of the body which are toward an end of the body.
  • Superior structures are toward the head (cranial) while inferior (caudal) structures are toward the feet.
  • Examples include the superior and inferior vena cava, which carry deoxygenated blood away from the head (superior) and from the lower body (inferior) to the heart.
  • Anterior and posterior are sometimes used in place of superior and inferior, respectively.

• 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.

• 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.
  • It is formed by the superior cardiac branch of the left sympathetic trunk and the lower superior cervical cardiac branch of the left vagus nerve.
  • It is situated on the sides and front of the aorta, between the origins of the superior and inferior mesenteric arteries.
  • From this plexus arise parts of the spermatic, the inferior mesenteric, and the hypogastric plexuses; it also distributes filaments to the inferior vena cava.
  • The superior hypogastric plexus (in older texts, hypogastric plexus or presacral nerve) is a plexus of nerves situated on the vertebral bodies below the bifurcation of the abdominal aorta.

• 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 superior epigastric vein refers to a blood vessel that carries deoxygenated blood and drains into the internal thoracic vein.
  • The inferior epigastric vein refers to the vein that drains into the external iliac vein and arises from the superior epigastric vein.
  • 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.

• Short-Term Neural Control

  • 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.
  • 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.

• Lymphatic Tissue Development

  • Each jugular lymph sac retains at least one connection with its jugular vein, the left one developing into the superior portion of the thoracic duct.
  • It develops from the primitive vena cava and mesonephric veins.