thoracic cage, rib cage, thoracic cavity by dr shahid alam

1. Axial Skeleton (Thoracic Cage)
Dr Shahid Alam PT
DPT (KMU),
MSPT-Neuro (KMU)
Pharm-B (PCP)
shahidalamawan@gmail.com

2. The Thoracic Cage
 The skeleton of the chest
 Supports the thoracic cavity
 Consists of:
– thoracic vertebrae
– ribs
– sternum (breastbone)
 The Rib Cage
 Formed of ribs and sternum

3. The Thoracic Cage
 Functions of the Thoracic Cage
 Protects organs of the thoracic cavity Heart,
lungs, trachea, and esophagus.
 Attaches muscles
 For respiration
 Of the vertebral column
 Of the pectoral girdle
 Of the upper limbs

4. The Thoracic Cage
Figure 7–23a The Thoracic Cage.

5. The Thoracic Cage
Figure 7–23b The Thoracic Cage.

7. The Thoracic Cage
 The sternum
 A flat bone
 In the midline of the anterior chest wall
 Three parts of the sternum
 The manubrium
 The sternal body
 The xiphoid process

8. The Thoracic Cage
 Manubrium
 The manubrium is the superior portion of the
sternum. It articulates with the body of the
sternum at the manubriosternal joint.
 Broad, triangular shape
 Articulates with clavicles (collarbones)
 Articulates with cartilages of first rib pair

9. The Thoracic Cage
 The sternal angle (angle of Louis), formed by
the articulation of the manubrium with the body
of the sternum, can be recognized by the
presence of a transverse ridge on the anterior
aspect of the sternum. The transverse ridge lies
at the level of the 2nd costal cartilage, the point
from which all costal cartilages and ribs are
counted. The sternal angle lies opposite the
intervertebral disc between the 4th and 5th
thoracic vertebrae.

10. The Thoracic Cage
 The sternal body
 Is tongue-shaped
 Attaches to the manubrium
 Attaches to costal cartilages of ribs 2–7
 The xiphoid process
 Is the smallest part of the sternum
 Attaches to the sternal body at the xiphisternal joint.
 Attaches to diaphragm and rectus abdominis muscles

12. Sternum.

13. The Thoracic Cage
 Development of the Sternum
 The developing sternal body
 Consists of four unfused bones
 Completes fusion about age 25
 Leaving transverse lines
 The xiphoid process
 Is the last part of sternum to fuse
 Can easily be broken away

14. The Thoracic Cage
 Ribs
 Are mobile
 Can absorb shock
 Functions of ribs
 Rib movements (breathing):
– affect width and depth of thoracic cage
– changing its volume

15. The Thoracic Cage
 Ribs (costae)
 Are 12 pairs of long, curved, flat bones
 Attached posteriorly to the thoracic vertebrae.
 Extending from the thoracic vertebrae
 Ribs are divided into two types
 True ribs
 False ribs

16. The Thoracic Cage
 Ribs 1–7 (true ribs)
 Vertebro-sternal ribs
 Attached anteriorly to the sternum by costal
cartilages
 Ribs 8–12 (false ribs)
 Do not attach directly to the sternum.
 Vertebro-chondral ribs (ribs 8–10)
 The 8th, 9th, and 10th pairs of ribs are attached
anteriorly to each other and to the 7th rib by means of
their costal cartilages and small synovial joints.

17. The Thoracic Cage
 Floating ribs: The 11th and 12th pairs
have no anterior attachment.
 Floating or vertebral ribs (ribs 11–12)
 Connect only to the vertebrae and back
muscles
 Have no connection with the sternum

18. Rib Anatomy
1. Typical Rib
 A typical rib is a long, twisted, flat bone
having a rounded, smooth superior border
and a sharp, thin inferior border. The
inferior border overhangs and forms the
costal groove, which accommodates the
intercostal vessels and nerve.
The anterior end of each rib is attached to
the corresponding costal cartilage.
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19. Rib Anatomy
 The head has two facets for anterior and posterior
articulation.
 The neck is a constricted portion situated between the
head and the tubercle.
 The tubercle is a prominence on the outer surface of the
rib at the junction of the neck with the shaft.
 The shaft is thin and flattened and twisted on its long
axis. Its inferior border has the costal groove.
 The angle is where the shaft of the rib bends sharply
forward.

20. Rib Anatomy
2. Atypical Rib
 The rib which is short and does not have a
proper costal grove, angle and shaft.
 The 1st rib is important clinically because
of its close relationship to the lower nerves
of the brachial plexus and the main
vessels to the arm, namely, the subclavian
artery and vein.

21. Rib Anatomy
 Typical Ribs
must have a
 Head
 Neck
 Tubercle
 Angle
 Shaft
 Subcostal
Groove
•Atypical Ribs
•No.1-short, flat, wide,
Supports Subclavian vessels.
•No.11, 12 don’t articulate
with transverse processes, or
anteriorly at all.
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22. The Thoracic Cage
Figure 7–24b Typical Ribs.

24. Atypical ribs.

25. Costal Cartilages
 Costal cartilages are bars of cartilage connecting the
upper seven ribs to the lateral edge of the sternum and
the 8th, 9th, and 10th ribs to the cartilage immediately
above. cartilages of the 11th and 12th ribs end in the
abdominal musculature.
 The costal cartilages contribute significantly to the
elasticity and mobility of the thoracic walls. In old age,
the costal cartilages tend to lose some of their flexibility
as the result of superficial calcification