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
Triangles of the neck the neck, from the sternum and clavicle below, to the mastoid process and occipital bone above. The triangular space in front of this muscle is called the anterior triangle of the neck; and that behind it, the posterior triangle of the neck. The anterior triangle is further divided into muscular, carotid, submandibular and submental and the posterior into occipital and subclavian triangles. The use of the divisions described as the triangles of the neck permit the effective communication of the location of palpable masses located in the neck between healthcare professionals. The common anterior midline of the swellings are: Triangles