A 55-year-old male presented with severe central chest pain after a rear-ended MVA at 60kph. He had a seat belt sign and sternal fracture. The document discusses the anatomy of the thoracic cage including the sternum, ribs, costal cartilage, vertebrae, and their articulations. Accessory ribs, sternal foramina, and rib fractures are also described. Images show normal anatomy and injuries like flail chest and splenic laceration from rib fractures. Resources for further information are provided.

1. OSTEOLOGY OF
THORACIC
CAGE
BY
DR. ABDUL WAHEED ANSARI
CHAIRPERSON & PROF. ANATOMY
RAK COMS.
3/26/2014 1

2. A 55 year old male is brought into your trauma bay c/o of severe central
chest pain that is reproducible on palpation and movement , post being
involved in a rear ended MVA at 60kph.
Seat belt sign with sternal fracture
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3. Sternum
• The sternum (breastbone) located in the
anterior midline of the body is a flat bone
approximately 15 cm long consisting of three
regions.
• The manubrium (the superior portion)
articulates with the clavicles laterally and
with the first two pairs of ribs.
• The body (which forms the bulk of the
sternum) bears notches that articulate with
the costal cartilages of the third to seventh
pairs of ribs.
• At the inferior end of the sternum is the
small, variably-shaped xiphoid process,
which although formed of hyaline cartilage in
youth, is usually ossified in adults.
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4. Sternal foramen
• A sternal foramen is a round or ovoid
congenital bony defect that results
from incomplete fusion of the
sternal ossification centres. The
estimated prevalence is 4.5%.
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5. Accessory ribs
• Cervical ribs at C7. Plain antero-
posterior radiographs
demonstrate C7 vertebra
bearing a pair of ribs, left larger
than right, which cannot be
considered thoracic because
they do not articulate with the
manubrium.
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6. Ribs fractures
Flail chest is the most common serious injury to the ribs. It
occurs when three or more ribs are broken in at least two
places, front and back.
The injured area of ribcage sinks in when the person inhales
instead of lifting outwards.( Paradoxical movement).3/26/2014 6

7. The ribcage consists of 24 curved ribs arranged in 12 pairs.
• The next three pairs of ribs aren’t
connected to the sternum. Instead,
costal cartilage attaches these
‘false ribs’ to the last pair of true
ribs.
• The remaining two pairs aren’t
attached at the front of the body at
all and are known as ‘floating ribs’.
• Each pair is attached to a
vertebra in the spine.
• At the front of the body, the first
seven pairs of ribs are attached
directly to the sternum
(breastbone) by cartilage known
as costal cartilage.
• These ribs are often called
‘true ribs’.
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8. 3/26/2014 8

9. 11th & 12th ribs (6, 5)
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10. 11th and 12th ribs are related to both
kidneys
Abdominal CT, spleen laceration
Common causes of splenic lacerations include MVA( Motor
vehicle accident) or other high speed deceleration injuries.
These produce lower rib fractures which can lacerate the
spleen or liver. The patient may present with LUQ pain and
referred pain to the shoulder secondary to phrenic nerve
irritation (Kehr’s sign).
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11. Splenic rupture due to rib fractures on left
side (9th+10th+11th ribs)
• A father brings his 15-year-old
son to the emergency
department because the son has
a large bruise over his lower left
ribs. This resulted from being
struck by a car accident. In
addition to complaining of pain
in the upper portion of his left
abdomen, the patient also has
pain in his left shoulder, which
seems to be aggravated with
movement.
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12. Thoracic vertebrae
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13. Costal facets on transverse process and demi-
facets on upper and lower borders of the
body/centrum
• Unique thoracic features:
Demi facets for articulation with rib
head, seen from side (except for 11th
and 12th.),
• Articular facets on transverse
processes (for rib tubercle) and
• long delicate spinous processes
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14. Cervical vertebrae
Unique cervical features:
• Transverse foramina in the
transverse processes
• Bifurcated spinous process
• Typical are 3-6th
• Atypical are 1st , 2nd and 7th.
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15. Lumbar vertebra features
• Heavy centrum
• Broad heavy spinous process
• Transverse process lacks facets
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16. Sacrum
• Unique features are
• 5 pieces are conjoint together
• Triangular piece at the tail end
of vertebral column.
• Below it is the degenerating
part of back bone, the coccyx.
• It consists of three to five
vertebrae. It is roughly
triangular, with the tip of the
triangle pointing down.
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17. Rib & vertebra articulation
• 1. Articular Facet of Rib
• 2. Interarticular Crest
• 3. Neck
• 4. Articular Portion of Tubercle
• 5. Nonarticular Portion of Tubercle
• 6. Angle of Rib
• 7. Costal Groove
• 8. Body of Rib
• 9. Articular Facet of Transverse Process
• 10. Transverse Process
• 11. Spinous Process
• 12. Lamina
• 13. Vertebral Foramen
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18. Normal curvatures of back bone
• When looking from the side, the spine has normal
curvatures.
• In the neck (cervical spine) and low back (lumbar
spine) there is normally an inward curvature.
Convex anteriorly and concave dorsally.
• In the thoracic spine there is an outward
curvature. Concave anteriorly and convex
posteriorly.
• The fetal curvature is universally concave anteriorly
and convex dorsally.
• The cervical and lumbar curvature develops after a
child develops balancing his head over his neck
and lumbar curvature develops after the child
starts walking.
• The thoracic and sacral curvature remains concave
even in adult life, anteriorly.
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19. Radiology of thoracic vertebrae
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20. Resources
• https://www.spinemd.com/conditions-
diagnoses/cervical-kyphosis-reston-va.php
• https://home.comcast.net/~wnor/thoraxbon
es.htm
• http://web.uni-
plovdiv.bg/stu1104541018/docs/res/skandala
kis'%20surgical%20anatomy%20-
%202004/Chapter%2002_%20Thoracic%20W
all%20and%20Pleurae.htm
• http://radiopaedia.org/articles/lumbar-rib
• http://www.wjgnet.com/2218-
5836/full/v2/i2/WJO-2-13-g002.htm
• http://www.davidicke.com/forum/showthrea
d.php?t=23140
• http://www.radpod.org/2008/04/08/sternal-
foramen/
• http://radiologypics.files.wordpress.com/201
3/03/thoracic-spine-lateral.jpg
• http://www.aaronswansonpt.com/breathing-
part-i-anatomy-mechanics/
• http://www.coccyx.org/whatisit/normal.htm
• Essential Clinical anatomy-4th edition- Keith
Moore ( pages 48-55).
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