1. THORAX

2. THE THORACIC CAGE :- Boundaries: Behind: In front:
Bodies of twelve thoracic vertebra and their intervening discs
Posterior parts of ribs
In front:
Sternum
Anterior part of ribs and their costal cartilages

3. On each side: Inlet of thorax: Outlet: Twelve ribs
It is reniform in shape
Outlet:
It is closed by the diaphragm

4. Skeleton of thorax:
Thoracic vertebra
Ribs
Sternum

5. Thoracic vertebra: Classification: They are 12 in number
They are recognized by the presence of costal facets on sides of the bodies and transverse process
Classification:
Typical thoracic vertebra:
Second to Eight
Atypical thoracic vertebra:
First, Nine to Twelve

6. Features of typical thoracic vertebra:
Body , Vertebral foramen,
Superior articular facets
Transverse process & Spinous process

7. Body:
It is heart shape
Presence of two two costal demifacets

9. Vertebral foramen: Small and circular in shape Pedicles are short
Lamina are short, thick and broad

10. The transverse process:
Tips bear oval costal facets

12. Spinous process:
Long and slopes downward

13. Sternum:
Consists of three parts
Manubrium
Body
Xiphoid process

14. Manubrium:

15. Body:

16. Xiphoid process:

17. THE RIBS: Arranged in twelve pairs
Posteriorly it articulates with the thoracic vertebra
Anteriorly joins with the sternum through their respective costal cartilages directly or indirectly

18. True ribs: False ribs: Typical ribs: Atypical ribs:
Classification of ribs:
True ribs:
Upper seven pairs (Vertebrosternal ribs)
False ribs:
Lower five pairs
(Vertebro-chondral ribs)
Typical ribs:
3rd to 9th ribs
Atypical ribs:
1st, 2nd, 10th 11th and 12th ribs

19. Typical ribs:
Sternal end
Vertebral end
Intervening shaft

20. Sternal end:
Lower than vertebral end and receives its own costal cartilage

21. Vertebral end:
It includes:
- Head
- Neck
- Tubercle

23. Shaft:
It is thin flat and curved

24. Applied anatomy:
Fracture of ribs:
Pneumothorax or Haemothorax

25. INTERCOSTAL SPACE

26. Intercostal space: Eleven in number on each side
Last two intercostal spaces are open in front

27. Typical Intercostal space:
Those spaces intervening between typical ribs and traversed by vessels and nerves which are confined to the thoracic wall, are known as typical intercostal space
As such 3rd , 4th, 5th and 6th intercostal space are typical

28. Boundaries of typical intercostal space:
Above:
Lower margin of upper rib and its cartilage
Below:
Upper margin of the lower rib and its cartilage
In front:
Lateral border of sternum between the costal notches
Behind:
Body of corresponding thoracic vertebra

29. Contents of space:
Muscles
Vessels and
Nerves

30. Muscles: They are arranged in three sheets from outside to inside:
Intercostalis externus
Intercostalis internus
Intercostalis intimus

31. Intercostalis externus:

32. Intercostalis internus:

33. Intercostalis intimus:
It occupies middle 2/4th of typical intercostal space
Intercostal vessels and nerves passes between intercostalis internus and intimus muscle

34. Arteries: Intercostal vessels:
In each space the arteries are arranged in two groups
Anterior intercostal arteries
Posterior intercostal arteries

35. Anterior intercostal arteries:
Upper six spaces:
Internal thoracic artery
Lower three spaces:
Musculo-phrenic artery

36. Posterior intercostal arteries:
Upper two spaces:
Superior intercostal artery
Lower nine spaces:
Descending thoracic aorta

38. Anterior intercostal veins Internal thoracic vein
In each space the veins are arranged in two groups
Anterior intercostal veins
Upper six spaces
Lower three spaces
Internal thoracic vein
Musculophrenic vein

39. Posterior intercostal veins
On right side
On left side
Azygous vein
Hemiazygous vein

41. intercostal Nerve: They are eleven in number
Each nerve is ventral ramus of a thoracic nerve
Ventral ramus of 1st thoracic nerve forms lower trunk of brachial plexus
Lateral cutaneous branch of 2nd intercostal nerve remains as intercostobrachial nerve
3rd to 6th intercostal nerves are called as typical intercostal nerves
7th to 11th intercostal nerves appears in anterior abdominal wall

42. Branches: Rami communicantes Collateral branch
Lateral cutaneous branch
Muscular branches run to the intercostal muscles.
Pleural sensory branches go to the parietal pleura.
Peritoneal sensory branches (7th to 11th intercostal nerves only) run to the parietal peritoneum

43. Applied anatomy: Intercostal neuralgia: Herpes zoster
It is a sharp burning pain in the area of skin supplied by thoracic spinal nerve produced by rib fracture
Herpes zoster
Caused by a virus called as varicella-zoster virus