1. Anatomy of The Thoracic Region
Mahmoud Alshirbini, MD, PHD

2. Basic Anatomical Planes
Anterior VS. Posterior
Superior (cranial, beak of spine) VS. Inferior (caudal- tail of spine)
Midline (median) means the mid-sagittal
The para-sagittal plane (lateral to the midline)
Medial (towards the midline) VS. Lateral (away from the midline)

4. Proximal (think proximity ) VS. Distal (think distance)
Superficial (outside e.g. skin) VS. Deep (inside e.g. organs)
Sagittal
Frontal (coronal)
Horizontal (transverse or axial)

5. Regional anatomy The thorax is an irregularly shaped cylinder with a narrow opening ( thoracic inlet) superiorly and a relatively large opening (thoracic outlet) inferiorly.
The thorax consists of: ■ Thoracic wall (cage) ■ Two pleural cavities ■ The lungs ■ The mediastinum.

6. Muscles attached to the anterior thoracic wall provide some of this support, and together with their associated tissues, nerves, and vessels, and the overlying skin and superficial fascia, define the pectoral region.

7. The thorax is the body cavity enclosing and protecting the heart, lungs, and great vessels
a conduit for structures passing between the neck and the abdomen
plays a principal role in breathing.
The thorax also provides support for the upper limb.

9. The thoracic skeleton
Thoracic skeleton consists of: -12 thoracic vertebrae (posteriorly) - 12 pairs of ribs (on either sides) - 12 pairs of costal cartilages - Sternum (anteriorly)

11. The Sternum
It is a flat dagger-shaped bone which Supports and articulates with the clavicles & the upper 7 pairs of ribs Consists of:
it is formed of 3 parts : (1) manubrium
(2) body
(3) xiphoid process
1st costal cartilage forms articulation with manubrium
2nd costal cartilage forms articulation with manubriosternal joint
3rd- 7th costal cartilage forms articulations with the body of the sternum

13. The ribs 1st thoracic vertebra associated with the 1st rib
1-7 form direct articulations with the sternum via costal cartilage (true)
Ribs 8-10 reach costal cartilage above, forming indirect articulations (false )
11 and 12 lack anterior attachment (floating)
Articulations (= joints)
with vertebral column – heads (inferior to anterior articulations with costal cartilage)
with costal cartilages – tubercles

17. The 7th rib forms its articulation at the body-xiphoid joint
Ribs 11 and 12 do not form articulations with the sternum, and are known as floating ribs
The costal cartilage forms articulations with the sternum via articular facets
The attachment site for rib 1 is different than the rest (a NON-synovial joint)
Superior of the sternum is the articular site for the clavicle, as well as the jugular notch

18. Thoracic vertebrae 2- Vertebral Arch 3- Vertebral Foramen
They are 12 "rib bearing vertebrae _each vertebra is formed of 2 main parts
1- Vertebral Body
2- Vertebral Arch
3- Vertebral Foramen

20. 1- Vertebral Body
It is the ventral strong 'part of the vertebra
it transmits the body weight downwards

21. 2- Vertebral arch
it is the dorsal part which surrounds the spinal cord - it is formed of the following parts
(a) Pedicle
(b) lamina
(c) Transverse process
(d) Spinous process (Spine)
(e) 2 Superior articular processes
(f) 2 Inferior articular processes

23. 3- Vertebral foramen
lies between the vertebral body and the vertebral arch
The successive vertebral foramina form the vertebral canal which lodges the spinal cord

24. How Vertebrae are connected together
1) Vertebral bodies: are Connected together by (a) the inter-vertebral discs (2ry Cartilaginous joints). (b) the ant-longitudinal Iig. : Connecting the ant.surface of the vertebral bodies. (c) the post. longitudinal Iig.: Connecting the post, surfaces of the vertebral bodies. (2) Laminae : are Connected together by ligamenta flava (Contain yellow elastic fibres). (3) transverse processes: are connected by inter transverse ligaments

26. (4) the Spines: are connected by
(a) interspinous ligaments: Connecting the adjoining spines
(b) supraspinous ligament: Connecting the tips of spines ( from c7 to sacrum)
(5) Articular processes : of adjoining vertebrae are Connected by the fibrous capsules of the intervertebral joints

27. Classification of thoracic Vertebrae
Typical vertebrae (2nd-8th)
Atypical vertebrae (1st,9th,10th,11th,12th)

28. Characters of the typical thoracic vertebrae
The body is heart-Shaped and has sup. and inf. Demifacet for articulation with heads of. ribs
The foramen is narrow and circular
The transverse process is directed posterolaterally and has an articular facet near Its tip anteriorly, for articulation with the tubercle of the numerically corresponding rib
the transverse process becomes progressively shorter from T1 to T 12

31. Intercostal spaces The spaces between each 2 successive ribs
11 spaces exist between the 12 ribs on each side
Structure:
(a) Intercostal muscles and membranes arranged in 3 layers
(b) a neurovascular bundle (VAN)

32. Intercostal muscles Arranged in 3 layers in each space:
1-Outer layer : external intercostal muscle
2-Middle layer: internal intercostal muscle
3- Inner layer: transversus thoracic muscle , incomplete muscle formed of 3 separate muscles;
(a) Sternocostlis m.
(b) Innermost intercostal m.
(c) Subcostalis m.

33. Intercostal neurovascular branches
Consist of:
Vein – most superior
Artery
Intercostal nerve – most inferior
Runs just inferior to each rib, deep to the internal intercostal mm. superficial to the innermost intercostal mm.( between the internal and innermost)

35. The intercostal muscles
External intercostals – form inferiorly and laterally from lower border of rib above to rib below (lateral if considering origin to be vertebral column), Replaced by anterior external intercostal membrane at costo-chondral (rib-cartilage) junction
Internal intercostals – attachments begin anteriorly at the sternum- from lower border of rib above to rib below - fibres directed at right angles to external intercostals, Replaced by membrane posteriorly
Innermost intercostals.

38. Muscles expanding chest and lung volume
The inferior thorax is larger in size to the superior thorax
Most lung tissue and capacity for lung expansion lies in the inferior thorax
The diaphragm has a flat central tendon with muscle radiating to costal margin and vertebrae.
On inhalation: Dome flattens to increase vertical diameter of chest
Costal margin is pulled up to increase transverse (horizontal) and antero-posterior diameters

39. The intercostal muscles have another role: they stiffen the chest wall to improve efficiency of breathing movements
The ribs move in ways to either increase or decrease chest volume.
In order to increase chest volume:
The sternum moves superior and anterior
The lateral shaft of the ribs is elevated

40. Thoracic inlet (superior aperture)
It is the upper opening of the thoracic cage at its junction with the root of the neck
Boundaries &structures :
Discussed in details later in this section

41. Thoracic outlet (inferior aperture)
It is the lower opening of the thoracic Cage at its junction with The abdomen
Boundaries and structures passing through it will be discussed later

42. Intercostal Nerves They are the ant. 1ry rami of the thoracic nerves.
11 pairs (relating to thoracic vertebrae 1-11)
1 subcostal nerve which relates to T12
May be motor and/or sensory
Consists of two main branches:
Lateral cutaneous branch – which then subdivides into the posterior and anterior branch
Anterior cutaneous branch – which then subdivides into the medial and lateral branch
Supply the intercostal spaces and muscles

43. Classification of intercostal nerves
1) 2 special nerves :
1st nerve, most of its fibers ascend to join the brachial plexus
The last (subcostal), runs all its course in the abdominal wall
2) 5 typical intercostal nerves : from 2nd to 6th intercostal nerves, they run all their course in the thoracic wall
3) 5 non-typical nerves: from 7th to 11th , part of their course in the thoracic wall and part in the abdominal wall

44. Branches of the intercostal nerves
1- Ganglionic branches 2-Collateral branches (motor) 3-Lateral cutaneous branch 4-Anterior cutaneous branch 5-Muscular branches 6-Pleural and peritoneal branches 7-Articular branches

46. Vascular Components
Each intercostal artery joins (anastomoses) with a major artery at each end of the intercostal space
Posteriorly the intercostal arteries are branches of the aorta
anteriorly the intercostal arteries are branches of the internal thoracic artery

52. The Thoracic cavity
Filled laterally by the lungs - each lying in its pleural cavity
Space between the pleural cavities = mediastinum
Heart (lying in its pericardial sac)
Great vessels
Oesophagus
Trachea
Thymus
Thoracic duct and other major lymph trunks
Lymph nodes
Phrenic and vagus nerves

53. The thoracic inlet Also known as the superior thoracic aperture
Ring formed of:
T1 (body of first thoracic vertebra) (post.)
1st ribs (on either side)
Manubrium (ant.)

54. Contents of Thoracic Inlet
Great vessels heading for neck and upper limb:
Common carotid artery
Internal jugular vein
Subclavian artery and vein (vein anterior to artery)
Esophagus
Trachea
Nerves and lymphatic system
Also apex of the right lung is superior to the clavicle

58. Thank you