Superior vena cava
The superior vena cava is truly superior, a large diameter, yet short, vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

 that carries deoxygenated blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 from the upper half of the body to the heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

's right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...

. It is located in the anterior right superior mediastinum.

It is formed by the left and right brachiocephalic vein
Brachiocephalic vein
The left and right brachiocephalic veins in the upper chest are formed by the union of each corresponding internal jugular vein and subclavian vein...

s, (also referred to as the innominate veins) which also receive blood from the upper limb
Upper limb
The upper limb or upper extremity is the region in an animal extending from the deltoid region to the hand, including the arm, axilla and shoulder.-Definition:...

s, head
In anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose and mouth . Some very simple animals may not have a head, but many bilaterally symmetric forms do....

 and neck
The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...

, behind the lower border of the first right costal cartilage. The azygos vein
Azygos vein
The azygos vein is a vein running up the right side of the thoracic vertebral column. It can also provide an alternate path for blood to the right atrium by allowing the blood to flow between the venae cavae when one vena cava is blocked.-Structure:...

 joins it just before it enters the right atrium, at the upper right front portion of the heart. It is also known as the cranial vena cava in animals.

No valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...

 separates the superior vena cava from the right atrium. As a result, the (right) atrial and (right) ventricular contractions are conducted up into the internal jugular vein
Internal jugular vein
The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

 and, through the sternocleidomastoid muscle
Sternocleidomastoid muscle
In human anatomy, the sternocleidomastoid muscle , also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the anterior portion of the neck...

, can be seen as the jugular venous pressure
Jugular venous pressure
The jugular venous pressure is the indirectly observed pressure over the venous system...

. In tricuspid valve
Tricuspid valve
The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle. The normal tricuspid valve usually has three leaflets and three papillary muscles. They are connected to the papillary muscles by the chordae...

Tricuspid insufficiency
Tricuspid insufficiency , a valvular heart disease also called tricuspid regurgitation , refers to the failure of the heart's tricuspid valve to close properly during systole. As a result, with each heart beat some blood passes from the right ventricle to the right atrium, the opposite of the...

, these pulsations are very strong.

See also

  • Persistent left superior vena cava
    Persistent left superior vena cava
    In anatomy, a persistent left superior vena cava is the most common variation of the thoracic venous system, is prevalent in 0.3% of the population, and an embryologic remnant that results from a failure to involute.-Presentation:...

  • Superior vena cava syndrome
    Superior vena cava syndrome
    Superior vena cava syndrome , or superior vena cava obstruction , is usually the result of the direct obstruction of the superior vena cava by malignancies such as compression of the vessel wall by right upper lobe tumors or thymoma and/or mediastinal lymphadenopathy. The most common malignancies...

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