Jugular vein
From Wikipedia, the free encyclopedia
| Vein: Jugular vein | ||
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| The veins of the neck, viewed from in front. | ||
| Gray's | subject #168 | |
| MeSH | A07.231.908.498 | |
The external and internal jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava. The internal jugular vein is formed by the anastomosis of blood from the sigmoid sinus of the dura mater and the common facial vein. The internal jugular runs with the common carotid artery and vagus nerve inside the carotid sheath. It provides venous drainage for the contents of the skull. The external jugular runs superficially to sternocleidomastoid. Both connect to the subclavian vein, the external jugular joining more laterally than the internal. The subclavian veins from both side then join to form the superior vena cava[1]. In popular culture, the jugular is stereotypically what dogs and other animals are thought to go after with the intent of killing another animal.
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[edit] Clinical Relevance
The jugular veins are relatively superficial and not protected by tissues such as bone or cartilage. This makes it susceptible to damage. Due to the large volumes of blood that flow though the jugular veins, damage to the jugulars can quickly cause significant blood loss which can lead to hypovolaemic shock and then death if not treated.
As there are no valves between the right atrium of the heart and the internal jugular, blood can flow back into the internal jugular when the pressure in the atrium is sufficiently high. This can be seen from the outside, and allows one to estimate the pressure in the atrium. The pulsation seen is called the jugular venous pressure, or JVP. This is normally viewed with the patient at 45 degrees turning their head slightly away from the observer. The JVP can be raised in a number of conditions, such as right ventricular failure (heart failure), tricuspid stenosis, tricuspid regurgitation and cardiac tamponade[2]. The JVP can also be artificially raised by applying pressure to the liver (the hepatojugular reflux). This method is used to locate the JVP and distiguish it from the carotid pulse. Unlike the carotid pulse, the JVP is impalpable.
As the internal jugular is large, central and relatively superficial, it is often used to place venous lines. Such a line may be inserted for several reasons, such as to accurately measure the central venous pressure or to administer fluids when a line in a peripheral vein would be unsuitable (such as during resuscitation when peripheral veins are hard to locate). Because the internal jugular rarely varies in its location, it is easier to find than other veins. However sometimes when a line is inserted the jugular is missed and other structures such as the carotid artery or the vagus nerve (CN X) are punctured, causing damage to those structures.
[edit] Branches
[edit] Additional images
 Human embryo of about fourteen days, with yolk-sac. |
 Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries. |
