Air embolism and veins is greater than atmospheric pressure, an air embolus does not often happen when a blood vessel is injured. In the veins above the heart, such as in the head and neck, the venous pressure may be less than atmospheric and an injury may let air in. This is one reason why surgeons must be particularly careful when operating on the brain, and why the head of the bed is tilted down when inserting or removing a central venous catheter from the jugular or subclavian veins. When air enters the veins, it travels to the right side of the
Anterior spinal veins the intramedullary and extramedullary systems which are sets of highly reliable veins. This is because they are vastly redundant in what they do and so only fail under exceedingly unfavorable conditions. Their dependability can be compromised, however, by the bridge that connects them. This fragile link across the dura mater of the spine is known as the radiculomedullary veins. Although these veins connect the trustworthy intramedullary and extramedullary veins, they have no support network to protect them and are seen in much fewer numbers by comparison. This may lead to complications such as thrombosis. For example patients that have spinal