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Anatomy of the Thoracic Back (Upper Back)
The thoracic spine refers to the upper- and middle-back.
It joins the cervical spine at the bottom of the back of the
neck and extends down about five inches past the bottom of
the shoulder blades, where it connects with the lumbar
spine.
The thoracic spine is made up of twelve vertebrae,
labeled T1-T12. While the cervical spine is built for
flexibility (e.g. turning the head) and the lumbar spine is
built for power and flexibility (e.g. lifting heavy objects,
touching the toes), the thoracic spine is built for
stability. This stability plays an important role in holding
the body upright and providing protection for the vital
organs in the chest.
There are several features of the thoracic spine that
distinguish it from the lumbar and cervical spine:
- Limited flexibility. The rib cage
is connected to each level of the thoracic spine. One
rib is connected firmly on each side of each thoracic
vertebra, with one pair extending from either side of
T1, another pair from T2, and so on. The ribs attached
to T1-T10 curve around to meet at the front of the body
and attach to the chest wall, or sternum. Combined, the
thoracic spine and rib cage anchoring each level of the
spine from T1 – T10 provide both stability and a
protected space for the heart, lungs, liver and other
vital organs.
The ribs connected to T11 and T12 at the bottom of the
thoracic spine do not attach the sternum in front, but
do provide protection for the kidneys in the back of the
body. Because these levels have slightly less stability,
they are slightly more prone to problems that can cause
pain.
- Thinner intervertebral discs.
Between each of the spine’s 24 unfused vertebrae are
intervertebral discs, spongy pads that act as shock
absorbers. In the thoracic spine, the intervertebral
discs are thinner than in the neck or lower spine. This
adds to the thoracic spine’s relative inflexibility.
Despite the thinner discs, it is still less common to
have disc problems in the thoracic spine due to the
limited flexibility.
- Narrower spinal canal. The cervical
and thoracic spine forms a protected, hollow core for
the spinal cord to pass through, called the spinal
canal. This canal is most narrow in the thoracic spine,
and therefore the spinal cord is at a risk for damage if
a thoracic vertebra is injured.
Upper Back Pain and the Thoracic Spine
The thoracic spine is an intricate construct of bones,
connective tissues, nerves, muscles, spinal segments, and
joints. While the thoracic spine has a solid construction
and is relatively stable, it can also be a source of pain.
- Muscular problems. Upper back pain
is most commonly caused by muscle irritation or tension,
also called myofascial pain. The cause may be poor
posture or any type of irritation of the large back and
shoulder muscles.
- Joint Dysfunction. Pain caused by
joint dysfunction, where the ribs attach to the spine at
each level of the thoracic spine, can cause pain.
- Herniated or degenerative discs.
While less common in the thoracic spine,
degenerative disc disease or a thoracic herniated
disc can be a source of pain.
- Arthritis. Swelling due to
arthritis in the spine can cause tenderness, pressure to
the nerve, and limited range of motion. Often due to
wear and tear of the aging process, the cartilage in the
facet joints can become thin or disappear or can produce
an overgrowth of bone spurs and an enlargement of the
joints. Facet joint disorders of the thoracic spine can
result from osteoarthritis.
- Vertebral fractures.
Compression fractures due to osteoporosis are a main
cause of thoracic spine pain in the elderly. While
compression fractures can occur anywhere in the spine,
they typically occur in the lower vertebrae of the
thoracic spine (T9 – T12).
- Kyphosis (hunchback). In addition
to vertebral fractures,
kyphosis can be caused by many factors, such as poor
posture or a deformity. , such as
ankylosing spondylitis or Scheuermann’s kyphosis.
While kyphosis is primarily a deformity, it can also be
a source of pain.
- Scoliosis. Scoliosis is a condition
in which the spine abnormally curves sideways and can
sometimes produce upper back pain.
Occasionally, pain felt in the thoracic spine can be a
symptom of a more serious underlying disease or problem.
Both musculoskeletal diseases and non-orthopedic conditions
(such as a cancerous tumor exerting pressure on the spine)
can cause upper back pain, as well as certain diseases of
the heart, lungs, abdominal organs, or kidneys.
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