The thoracic duct typically arises from the cisterna chyli, and it carries lymph superiorly and drains it to the junction of the left internal jugular and subclavian veins (Figs. 51.1 and 51.2). While the thoracic duct is typically 45 cm in length (Smith et al. 2013). Van Pernis (1949) and Celis and Porter (1952) observed more variation, ranging from 36 to 45 cm. Jacobsson (1972) found that the diameter is usually greatest in the cervical region and smallest in the lower thoracic region. The external diameter fluctuated between 1.5 and 8 mm. Akcali et al. (2006) also measured the diameter of the thoracic duct. They found that at the levels of T5, T9, and T12, mean diameters were respectively 2.3, 2.6, and 3.3 mm. In addition, it seems to show an elastic property, being able to dilate to several times the normal width, depending on the amount of lymph flow (Smith et al. 2013).