Posterior Mediastinum - LO 4

4. What is the thoracic duct? Describe the course of the thoracic duct.

The thoracic duct is the major lymphatic vessel and duct of the body, receiving and conducting lymph from all but the right head & neck, right upper limb, and right half of the thorax. The thoracic duct receives lymph from the following sources:

• • Left jugular trunk,

  • Left subclavian trunk,

  • Left bronchomediastinal trunk

  • Cisterna chyli (a variable, dilated confluence of the lumbar and visceral lymphatic trunks of the abdominopelvic region).

The pattern of lymphatic trunk drainage is inconstant, thus it is not unusual for trunks to independently enter the vicinity of the venous angles without first joining a duct.

The thoracic duct enters the thoracic cavity through the aortic hiatus (near T12), ascends lateral (right) to the esophagus, transitions from right-to-left between the esophagus and vertebral column (near T5), ascends lateral (left) to the esophagus, and wraps posteriorly behind the subclavian a. (root of neck) to enter the venous system in the vicinity of the left venous angle.