The external jugular vein begins in the vicinity of the angle of the mandible, within or just inferior to the parotid gland. It runs just deep to the platysma muscle. Its course is approximated by a line connecting the mandibular angle and the middle of the clavicle. It crosses the sternocleidomastoid muscle and pierces the superficial lamina of the deep cervical fascia roofing the omoclavicular triangle. It continues its vertical course to end in either the subclavian or, about one-third of the time, the internal jugular vein. When it pierces the superficial lamina, its wall adheres to the fascia. This tends to hold a laceration of the vein open and predisposes the patient to air entrance if the vein is severed at this site. The vein can be occluded by pressure just superior to the middle of the clavicle, a point slightly posterior to the clavicular origin of the sternocleidomastoid muscle. The diameter of the external jugular vein is quite variable and appears to have an inverse relation to the diameter of the internal jugular veins. The right external jugular vein is typically larger in diameter than the left, partly because it is more closely aligned with the superior vena cava and thus the right atrium., Because the most common method is percutaneous internal jugular venous cannulation, several approaches (posterior, anterior, and ultrasound-guided) are discussed. This chapter also discusses placement of two types of implantable venous access devices: Ports and tunneled venous catheters., We found out the description of 30 different signs, symptoms, and blood biomarkers related to this condition, as well as 24 different reported causes of IJVthr..