Lateral medullary syndrome is caused by thrombosis of-

* Dorsolateral pa of the medulla is suplied by posterior inferior cerebellar aery ,which usually a branch of veebral aery *thrombosis of posterior inferior cerebellar aery ,therfore effects a wedge shaped area on the dorsolateral aspects of medulla and the inferior surface of cerebellum produce lateral medullary syndrome of wallenberg. Ref Harrison20th edition pg 2435