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The jugular vein is a well-recognized structure in both the lay and the medical community. Various phrases used by individuals relating to the jugular veins include such statements as "go for the jugular," "cut to the quick," "cut to the jugular," and "did it get the jugular?" The jugular venous system is the major drainage system for the head and cerebral structures. Table 16-1 demonstrates several considerations regarding the jugular veins. From the time one enters medical school, the physician is made aware of the jugular system. This first comes during direct anatomic dissection in the animal and cadaver laboratories where the structures and characteristics of the internal jugular vein (IJV) and external jugular vein (EJV) are well visualized along with their relationships to their accompanying muscular, neural, vascular, and pharyngeal structures. In physical diagnosis, the anatomic jugular system and many clinical relationships are pointed out to students. The venous system is usually larger and thin walled compared with accompanying arteries and thus acts as capacitance structures. Disease considerations are related to these veins by the instructors and how to recognize such implications of collapsed or dilated veins when the patient is lying down or in the upright or standing position. Correlation of these findings with cardiac and pericardial processes and the methods of examination are also discussed. The jugular system forms a vital connection between the structures of the head and chest.
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Veins are found in both the superficial and the deeper tissue levels divided by fascia and are connected transfascially by venous collaterals. Valves help direct the venous blood in the appropriate direction as it returns to the heart. The larger veins such as the jugular and the vena cava have fewer or no valves, but most other veins have one or more valves separated by a few centimeters. Histologic examination of the veins shows 1) the intima, which consists of the endothelium, the subendothelial connective tissue, and in the larger veins, an internal elastic membrane; 2) a media formed by smooth muscle cells usually arranged in bundles intermixed with fibrous networks that may be active and contractile, tributary veins with weaker and thinner walls, and collagen and elastic fibers in various amounts depending on the vein size and location, and 3) an adventitial layer around these vessels that carries the vasa vasorum (through the loose connective tissue), nerve fibers, and the lymphatic system. The veins may have a venous sheath surrounded by thin fibers. Superficial veins are located in the epifascial plane and held in place by a laminar system that protects them from stretching and tearing. As a bradytrophic system, the veins are also able to receive nutrition from their endoluminal side as oxygen-laden and nutritious blood passes through the ...