Azygous (also written as azygos) means for
something to occur as single or unpaired. For
example, the spine is an azygous structure
because it does not occur in pairs. The eyes,
ears, legs, and arms are examples of
structures that are not azygous because they
occur in sets of two. There is a vein in the
human body (and dogs and cats) known as the
azygos vein which traverses the right side of
the thoracic verterbral column.
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Veins are types of blood vessels that carry blood to the heart. The vertebral column is a
set of bones that surround the spine. Those bones in the thoracic area of the vertebral
column are behind an area of the body known as the thorax, which is another name for

There are also some muscles that are azygous. A common example is the azygous
muscle of the uvula (soft palate). The uvula is the small oval shaped area of tissue and
muscle fibers hanging from the back of the throat which helps articulate certain sounds in
human speech. Azygous comes from the Greek word "a" meaning "to do without," and the
Greek word "zygon" meaning "yoke." Put the two words together and you have "to do
without yoke." Yoke means to join together.
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