T1 through T12
T1 through T12 refers to the twelve vertebrae (bones that
form an opening in which the spinal cord passes) that are
behind an area of the body known as the thorax, which is
another name for chest. The thorax (chest) is a cage of
bones and cartilage (a type of tissue) that extends from the
bottom of the neck to a muscle known as the diaphragm,
which separates it from the belly. The letter "T" stands for
"thoracic," which is Greek for "chest." T1 refers to the 1st
thoracic bone, T2 to the 2nd thoracic bone, T3 to the 3rd
thoracic bone, and so on, until T12, which is the last thoracic
bone. T1 is at the top and T12 is at the bottom, with the
numbers in between going down the body in numerical order.
For example, T3 is below T2, T4 is below T3, and so on.
FEATURED BOOK: The Cervical and Thoracic Spine: Diagnosis and Therapy

These numeric levels are often mentioned on imaging studies of the spine such as
computerzed axial tomography (CT) scans or magnetic resonance imaging (MRI). CT
scanning is an advanced imaging technique that uses x-rays and computer technology to
produces clear and detailed picture of the body area being examined. MRI scans produce
extremely detailed pictures of the inside of the body by using very powerful magnets and
computer technology. Other designations for other levels of the vertebrae include a) C1
through C7, where C stands for the cervical (neck) area; b) L1 through L5, where L
stands for the lumbar (lower back) area, and c) S1 through S5, where S stands for the
sacral (sacrum) area. The thoracic vertebrae are located above the lumbar vertebrae and
below the cervical vertebrae.

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