thoracic duct

Examples of thoracic duct in the following topics:

• Lymph Trunks and Ducts

  • Two lymph ducts receive lymph from the lymph trunks.
  • The thoracic lymph duct, the largest lymph vessel in the body, takes lymph from the lower and left halves of the body.
  • Because the thoracic lymph duct drains the intestinal lymph trunks, it carries a mixture of lymph and emulsified fatty acids called chyle back to the bloodstream.
  • The thoracic duct drains into to the left subclavian vein while the right duct drains into the right subclavian vein, both at the junction between the respective vein and the jugular vein.
  • The lymph ducts each have internal valves at their junction with the subclavian vein.

• Thoracic Aorta

  • The thoracic aorta is the section of the aorta that travels through the thoracic cavity to carry blood to the head, neck, thorax and arms.
  • 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.
  • The thoracic aorta's relation, from above downward, is as follows: anteriorly with the root of the left lung, the pericardium, the esophagus and the diaphragm; posteriorly with the vertebral column; on the right side with the hemiazygos veins and thoracic duct; and on the left side with the left pleura and lung.
  • The posterior intercostal arteries are branches that originate throughout the length of the posterior aspect of the thoracic aorta.
  • The aorta, highlighted in red, includes the thoracic aorta, the section of the aorta which runs from the lower border of the fourth thoracic vertebra to the diaphragm.

• 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.

• Distribution of Lymphatic Vessels

  • The efferent lymph vessels in the left and lower side of the body drain into the left subclavian vein through the thoracic duct, while the efferent lymph vessels of the right side of the body drain into the right subclavian vein through the right lymphatic duct.
  • Lymph nodes found closer to the heart filter lymph fluid before it is returned to venous circulation through one of the two lymph ducts.

• Lymph Transport

  • Lymph transport refers to the transport of lymph fluid from the interstitial space inside the tissues of the body, through the lymph nodes, and into lymph ducts that return the fluid to venous circulation.
  • The sinuses converge at the hilum of the node, where lymph then leaves the node via an efferent lymphatic vessel toward either a more central lymph node or a lymph duct for drainage into one of the subclavian veins.
  • The lymph trunks then converge into the two lymph ducts, the right lymph duct and the thoracic duct.
  • These ducts take the lymph into the right and left subclavian veins, which flow into the vena cava.

• Great Vessels of the Heart

  • The subclavian veins are significant because the thoracic lymphatic duct drains lymph fluid into the subclavian veins, making the superior vena cava a site of lymph fluid recirculation into the plasma.
  • It is subdivided into the thoracic and abdominal aorta.
  • The thoracic aorta is  the part of the descending aorta above the diaphragm.
  • The right pulmonary veins pass behind the right atrium and superior vena cava while the left pass in front of the descending thoracic aorta.

• Lymphoid Tissue

  • This process begins with he lymph nodes closest to the thoracic and right lymph ducts, which arises from immature subclavian-jugular vein junction.

• Mammalian Systems and Protective Mechanisms

  • The muscular diaphragm, which facilitates breathing, is inferior to the lungs, marking the end of the thoracic cavity.
  • The terminal bronchioles then subdivide into respiratory bronchioles which subdivide into alveolar ducts.
  • Numerous alveoli (sing. alveolus) and alveolar sacs surround the alveolar ducts .
  • The alveolar ducts are attached to the end of each bronchiole; each duct ends in approximately 100 alveolar sacs.
  • Terminal bronchioles are connected by respiratory bronchioles to alveolar ducts and alveolar sacs.

• Thoracic Cage: Ribs

  • The ribs are long, curved bones that protect the lungs, heart, and other organs of the thoracic cavity.
  • The thoracic cage can expand and contract to facilitate breathing in association with the diaphragm; it also protects the lungs, heart, and other organs of the thoracic cavity.
  • Finally, the shaft forms the majority of the length of the rib as it curves around the thoracic cavity forming the rib cage.
  • The first thoracic vertebra has a rib attached to it that curves across to the sternum.

• Functional Anatomy of the Respiratory System

  • When the diaphragm contracts, the rib cage expands and the contents of the abdomen are moved downward, resulting in a larger thoracic volume and negative pressure (with respect to atmospheric pressure) inside the thorax.
  • During forced exhalation, as when blowing out a candle, the expiratory muscles, including the abdominal muscles and internal intercostal muscles, generate abdominal and thoracic pressure that force air out of the lungs.
  • The pulmonary alveoli are the terminal ends of the respiratory tree, outcropping from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood.