Learn the anatomy of the thorax in one hour!

1. THORAX
ANATOMAY OF
Dr. Rajith Eranga
www.rermedapps.com

2. THORACIC CAGE - Apertures
1. Superior Thoracic Aperture (Inlet)
T1, First rib, Manubrium
2. Inferior Thoracic Aperture (Outlet)
T12, Rib 11, Rib 12,
Costal margin, Xiphoid process

3. THORACIC WALL
Bones
Sternum, 24 Ribs, 12 Thoracic vertebrae
Muscles
a. Intrinsic Muscles
Intercostals, Subcostals, Transverse
Thoracis
a. Extrinsic Muscles
Pectoralis Major & Minor,
Serratus anterior, Subclavius

4. Parts - Manubrium, Body, Xiphoid Process
Joints
• Manubriosternal Joint – (Secondary Cartilaginous)
• Xiphisternal Joint – (Primary Cartilaginous)
• Sternoclavicular joint – (Synovial Saddle)
• Sternocostal joint 1st rib - (Primary Cartilaginous)
• Sternocostal joints 2nd to 7th ribs– (Synovial Plane)
Development
From 3 Sternabrae
STERNUM – Basic Anatomy

5. STERNUM – Vertebral Levels
T4/T5 Level
• Demarcates sup & inf mediastinum
• Bifurcation of trachea
• Bifurcation of pulmonary trunk
• Start & end of arch of aorta
• Formation of SVC
• Azygos vein joining SVC
• Thoracic duct – crossing
T2 Level
T9 Level
T5 to T8
T2 to T4

6. THORACIC VERTEBRAE - Classification
Classification
a. Typical
b. Atypical
Typical Thoracic Vertebrae
Parts – Heart shaped body, Lamina,
pedicles, spinous process
Unique – Costal facet on body, transverse
process
Atypical Thoracic Vertebrae
T1, T10, T11, T12 – Only single facet on body

7. Joints
• Intervertebral – Secondary cartilaginous
• Costovertebral – Synovial plane
• Costotransverse – Synovial Plane
Ligaments
• Supraspinous
• Interspinous
• Ligamentum flavum
• Posterior longitudinal
• Anterior longitudinal
THORACIC VERTEBRAE – Joints & Ligaments

8. RIBS - Classification
Classification
A. True/ False/ Floating
B. Typical/ Atypical
A. Ture Ribs / False Ribs / Floating Ribs
1. True - Ribs 1 to 7
2. False - Ribs 8 to 10
3. Floating - Ribs 11 to 12

9. RIBS - Classification
B. Typical & Atypical Ribs
1. Typical - Ribs 3 to 9 – Head with 2 demifacets,
neck, tubercle, angle, shaft
2. Atypical
• Rib 1 - single articular facet, shortest, most
curved, horizontal, Scalene Tubercle, grooves
• Rib 2 - roughened area for Serratus Anterior
• Rib 10 - single articular facet
• Rib 11 - single articular facet, no tubercle
• Rib 12 - single articular facet, no tubercle, no
subcostal groove

10. RIBS - Joints & Ligaments
Joints
• Costovertebral joints – Synovial plane
• Costotransverse joints - Synovial plane
• Costochondral joints – Primary Cartilaginous
• Sternochondral joints – Synovial Plane (Except 1st)
• Interchondaral joints – Synovial plane
Ligaments
1. (Medial) Costotransverse
2. Lateral costotransverse
3. Superior costotransverse
4. Radiate ligament

11. THORACIC WALL - Muscles
Intrinsic Muscles
1. External Intercostals
2. Internal Intercostals
3. Innermost Intercostals
4. Subcostals
5. Transverse Thoracis
Extrinsic Muscles
• Pectoralis Major & Minor
• Serratus Anterior
• Serratus Posterior Superior
• Serratus Posterior Inferior

12. THORACIC WALL - Intrinsic Muscles
External IC Internal IC Innermost IC Subcostals Sternocostalis
Tubercle to
Costochondral
junction
Sternum to
Angle
Incomplete
layer
Near angle,
Run 2-3 ribs
below
Lower sternum
to 2nd to 6th CC
Outer layer Middle layer Inner layer Inner layer Inner layer
Anteroinferior Posteroinferior Posteroinferior Posteroinferior Anteroinferior
Forced
Inspiration
Forced
Expiration
Forced
Expiration
Forced
Expiration
Forced
Expiration

13. DIAPHRAGM – Basic Anatomy
Attachments
Vertebral – Left Crus (L1-L2), Right Crus (L1-L3)
Costal – Lower 6 ribs & costal cartilages
Sternal – Xiphoid process
Innervation
Motor – Phrenic nerve (C3-C5)
Sensory – Phrenic nerve & lower intercostal nerves

14. DIAPHRAGM - Openings
Aortic (T12)
Aorta, Thoracic duct,
Azygos vein
Oesophageal (T10)
Oesophagus, 2 Vagal
trunks, Left gastric artery
Vena Caval (T8)
IVC, Right phrenic nerve

15. PLEURA – Basic Anatomy
Components
• Parietal Pleura
• Cervical
• Costal
• Diaphragmatic
• Mediastinal
• Visceral Pleura
Surface Marking
(Read)

16. PLEURA – Innervation
1. Costal Parietal Pleura
Intercostal nerves
2. Mediastinal Parietal Pleura
Phrenic nerve
3. Diaphragmatic Parietal Pleura
Phrenic nerve + lower 6 IC nerves
4. Visceral Pleura
Pulmonary plexus

17. PLEURA - Pleural Recesses
The potential spaces, where the visceral and
parietal pleura are relatively distant (Expiration).
1. Costomediastinal Recess
Between costal pleura & mediastinal pleura.
Prominent in Left side.
2. Costodiaphragmatic Recess
Between costal pleura & diaphragmatic pleura.

18. LUNGS - Basic Anatomy
Surfaces
1. Costal
2. Diaphragmatic
3. Mediastinal (Revise relations of each lung)
Borders
1. Anterior – Sharp (Cardiac notch in L)
2. Inferior – Shap
3. Posterior – Blunt

19. LUNGS – Lobes & Fissures
Lobes
• Left – 2 Lobes (Superior & Inferior)
• Right – 3 Lobes (Superior, Middle & Inferior)
Fissures
1. Oblique Fissure – Runs superoposterly
From - Inferior border
To - Posterior border
2. Horizontal Fissure (R Only) – Runs transversely
From - Sternum at 4th Rib
To - Oblique fissure

20. LUNGS - Hilum
Structures
• Bronchus
• Pulmonary artery
• Two pulmonary veins
• Bronchial arteries & veins
• Pulmonary autonomic plexus
• Lymphatics & LN
Dual blood supply (Pulmonary & Bronchial)
So that lung can survive in PE.

21. LUNGS – Lymphatic Drainage
Lymphatic Plexus in Lung
• Superficial lymphatic plexus – beneath pleura
• Deep lymphatic plexus – around vessels
Lymph Drainage Pathway
1. Intrapulmonary LN (within lung)
2. Bronchopulmonary LN (at hilum) 
3. Tracheobronchial LN (at bifurcation) 
4. Paratracheal LN (beside trachea)
5. Mediastinal Lymph Trunks 
6. Brachiocephalic veins
(Sometimes via Thoracic duct on L side)

22. LUNGS – Bronchopulmonary Segments
Definition
A portion of lung  Supplied by a specific
segmental bronchus, artery and vein.
“Functionally separate divisions of each lobes”
Structure
Wedge-shaped. Apex at hilum, base at surface.
Importance
• Pathologies (Eg : Atelectasis, Bronchiectasis)
• Bronchoscopy
• Surgical Resection

23. TRACHOBRONCHIAL TREE
Trachea
From Cricoid (C6) to Angle of Louis (T4/T5)
Bronchi
• Left (T6)
• Right (T5) - Shorter, Wider & Less vertical
• Angle of Carina - 600 (in adult), At T4/T5 (Mid Respiration)
Further Divisions
Main(1ry) Bronchi  Lobar(2ry) bronchi Segmental(3ry)
bronchi Conducting bronchioles Terminal bronchioles 
Respiratory bronchioles  Alveolar ducts Alveoli

24. MEDIASTINUM - Divisions
• Superior Mediastinum
• Inferior Mediastinum
a. Anterior Mediastinum
b. Middle Mediastinum
c. Posterior Mediastinum

25. PERICARDIUM
Layers of Pericardium
Fibrous Pericardium
Serous Pericardium
a. Parietal layer
b. Visceral layer (Epicardium)
Attachments of Fibrous Pericardium
• Adventitia of great vessels
• Central tendon of diaphragm
• Sternum – Sternopericarial ligament

26. PERICARDIUM
Recesses
• Transverse Sinus
• Oblique Sinus
Functions
• Fixes the heart
• Prevents overfilling
• Lubrication
• Protection from infections

27. PERICARDIUM
Blood Supply
• Pericardiophrenic artery
• Internal thoracic artery
• Musculophrenic artery
• Thoracic Aorta
Innervation
Phrenic nerve (C3,4,5)

28. CHAMBERS OF HEART
Right Atrium
Inflow – SVC, IVC, Coronary sinus
Outflow – Tricuspid valve
Cavity - two compartments – separated
by crista terminalis
• Posterior – Smooth (sinus venousus)
• Anterior – Rough (true atrium) –
Pectinate muscles
Interatrial Septum – Fossa Ovalis

29. CHAMBERS OF HEART
Right Ventricle
Inflow – Tricuspid valve
Outflow – Pulmonary Artery
(Infundibulum)
Cavity two compartments
• Smooth part (near infundiculum)
• Rough part – trabecular carniae
a. Muscular Ridges
b. Muscular Bridges
c. Papillary Muscles
Moderator Band (Septomarginal trabeculae) - RBB

30. CHAMBERS OF HEART
Left Atrium
Inflow – 4 Pulmonary veins
Outflow – Mitral valve
Cavity Two compartments
• Posterior – Smooth (sinus venousus)
• Anterior – Rough (true atrium) –
Pectinate muscles

31. CHAMBERS OF HEART
Left Ventricle
Inflow – Mitral valve
Outflow – Aorta
Cavity - two compartments
• Smooth part (near aortic vestibule)
• Rough part – trabecular carniae
Thickest Myocardium

32. HEART – Atrioventricular Valves
Tricuspid Valve
Anterior Cusp
Posterior Cusp
Septal Cusp
3 sets of Papillary muscles- connect to cusps via
cordi tendinae
• Anterior – Bulkiest
• Posterior
• Septal – Often absent
• Keep the valve closed during ventricular systole-
 prevent regurgitation

33. HEART – Atrioventricular Valves
Mitral Valve
Anterior Cusp
Posterior Cusp
• 2 sets of Papillary muscles  connect to cusps
via cordi tendinae
• Anterior - Bulkiest
• Posterior
• Keep the valve closed during ventricular systole-
 prevent regurgitation

34. HEART - Semilunar Valves
Semilunar Valves
1. Aortic Valve
2. Pulmonary Valve
3 valve cusps  blood fills in diastole  valvular
closure
Aortic Valve
Coronary arteries arises from aortic sinuses.
Left CA – Anterior coronary sinus
Right CA – Posterior coronary sinus

35. HEART – Arterial Supply
Two Coronary Arteries – From Aortic sinuses
1. LCA  Gives off LCx & LAD
2. RCA  Gives off RMA & PIVA (70%)
• Functional end arteries.
• SA & AV node, Posterior 1/3 of IV septum
(by PIVA) supplied by RCA.
Clinical
Coronary Angiogram (SVD, DVD, TVD)
Cardiac Dominance (which CA gives off PIVA)
{In left dominance (30%) – PIVA from LCA}

36. HEART – Venous Drainage
Coronary Sinus
Receives 5 main tributaries  Opens to RA
1. Great cardiac vein – in Anterior IV groove
2. Middle cardiac vein – in Posterior IV groove
3. Small cardiac vein – with RMA
4. Posterior cardiac vein – Posterior aspect of LV
5. Oblique cardiac vein – Posterior aspect of LA
Other Veins
• Anterior cardiac veins – drain Anterior surface to RA
• Venae cordis minimae – drain myocardium to cavity

37. OESOPHAGUS – Basic Anatomy
• 25 cm fibromuscular tube
• From C6 to T11 (At T10 leaves thorax)
• Cervical, Thoracic & Abdominal components
Blood Supply
Inferior thyroid, Thoracic aorta & Left Gastric
arteries
Lymph Drainage
• Superior 1/3  Deep cervical LN
• Middle 1/3  Mediastinal LN
• Lower 1/3  Coeliac LN

38. 1. Adventitia
2. Muscularis Propria (Outer
longitudinal & inner circular)
• Upper 2/3  Straited muscles
• Lower 1/3  Smooth muscles
3. Submucosa – Mucous glands
4. Mucosa – Non-keratinized Stratified
squamous epithelium
Barret’s Oesophagus - Read
OESOPHAGUS - Layers

39. THORACIC DUCT
Drain lymph from
1. Below the diaphragm
2. Left half above the diaphragm
From Cisterna Chyli  Through aortic
opening of diaphragm  on vertebral bodies
 inclines to left at T5  drains to Left
Brachiocephalic vein

40. THORACIC SYMPATHETIC TRUNK
• Runs lateral to vertebral bodies each side
• Connecting sympathetic paravertebral ganglia
• Behind Medial arcuate ligament  become abdominal
sympathetic trunk
Paravertebral ganglia receives preganglionic nerves. They can,
1. Synapse in the paravertebral ganglia at the same level
2. Ascend in chain & synapse in higher paravertebral ganglia
3. Descend in chain & synapse in lower paravertebral ganglia
4. Travel without synapsing (Splanchnic nerves) to synapse in
prevertebral sympathetic ganglia.

41. THORACIC SPLANCHNIC NERVES
• They are branches of sympathetic train that
carry preganglionic fibres to autonomic
plexuses.
• They synapse in prevertebral ganglia
(coeliac, mesenteric, renal etc)
• Lie medial to sympathetic trunk
3 Thoracic splanchnic nerves
1. Greater Splanchnic -T5-T9
2. Lesser Splanchnic - T10 & T11
3. Least Splanchnic -T12

42. THANK YOU 
END OF THE LECTURE