Changes

<p>The smaller vessels generally travel with blood vessels and nerves. Valves in the vessels prevent back flow and keep the flow of lymph unidirectional. As there is no central pump the movement of lymph is largely dependant on skeletal muscular activity.</p>

<p>The smaller vessels generally travel with blood vessels and nerves. Valves in the vessels prevent back flow and keep the flow of lymph unidirectional. As there is no central pump the movement of lymph is largely dependant on skeletal muscular activity.</p>

===Tracheal duct===

===Tracheal duct===

<p>The tracheal ducts are paired and originate from the retropharyngeal nodes (except horse) of the head. They run along the trachea before emptying into the thoracic and right lymphatic ducts or may empty directly into the jugular veins.</p>

<p>The tracheal ducts are paired and originate from the retropharyngeal nodes (except horse) of the head. They run along the trachea before emptying into the thoracic and right lymphatic ducts or may empty directly into the jugular veins.</p>

===Thoracic duct===  

===Thoracic duct===  

<p>Originating from the cistern chyli it passes through the aortic hiatus, travelling cranially through the mediastinum and along the left side of the trachea until it empties into the cranial vena cava or commonly the left jugular vein.</p>

<p>Originating from the cistern chyli it passes through the aortic hiatus, travelling cranially through the mediastinum and along the left side of the trachea until it empties into the cranial vena cava or commonly the left jugular vein.</p>