Thoracic Cage
Functions
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Protects vital organs within the thorax
Supports thorax during respiration,
Supports shoulder girdles and upper limbs
Provides attachment points for back, chest
and shoulder muscles.
Parts
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Composed of thoracic vertebrae (dorsal)
Ribs (laterally)
Sternum with costal cartilages (anteriorly).
Ribs and costal cartilages
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There are 12 pairs of ribs.
All 12 attach posteriorly to vertebral
column.
Pairs 1 – 7 and true ribs (attach directly to
sternum by costal cartilages)
8 – 12 are false ribs (attach indirectly or
lack a sternal attachment completely).
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8 – 10 attach indirectly by a common
cartilage.
11 and 12 are floating ribs and do not
attach to sternum at all.
Rib Cage
Sternum
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Divided into three parts, manubrium, body
and xiphoid process.
A flat bone approximately 6 inches long.
Manubrium (superior) is shaped like a
knot in a necktie.
Articulates with clavicle at clavicular
notches.
Sternum
Body
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Forms the bulk of the sternum.
Sides are notched where it articulates with
cartilages of the second to seventh ribs.
Body
Xiphoid process
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Forms inferior end of sternum.
Is hyaline cartilage in youth, but ossifies in
adults.
Articulates only with sternal body and
serves as attachment point for diaphragm
and some abdominal muscles.
Sternal landmarks
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Jugular notch
Sternal angle
Xiphisternal joint
Jugular notch
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Visible as a central indentation in the upper
border of manubrium.
Is generally in line with the disc between T2 and T-3.
Is also in line with the point where the left
common carotid artery issues from the
aorta.
Sternal angle
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Found where the manubrium joins the
sternal body.
Sternum is slightly angled at this point.
Can be felt as a horizontal ridge across
across front of sternum.
Landmark position for 2nd rib and the disc
between T-4 and T-5.
Xiphisternal angle
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Where sternal body and xiphoid process
fuse.
Lies opposite ninth thoracic vertebrae.