1. Clinical Anatomy Tony Serino, Ph.D. .
Mediastinum
Clinical Anatomy Tony Serino, Ph.D. .

2. Mediastinum: Topic Objectives
Be able to identify and describe the contents of the three major divisions of the mediastinum.
Be able to identify normal and pathological variations of the aortic arch and congenital heart defects.
Be able to explain differences and similarities between adult and fetal blood flow, and list changes needed at birth.
Be able to explain cardiac muscle cell depolarization and relate its significance to heart function.
Be able to identify and describe all structures of heart anatomy and their function.
Understand coronary circulation and its normal and some pathological variations.
Be able to trace the flow of blood through the heart chambers and relate it to valve operation and heart sounds.
Be able to identify and trace coronary electrical conduction and its relevance to EKG
Be able to explain cardiac rate and force of contraction control
Be able to calculate CO and SV
Be able to predict effects on heart performance with changes in CO and SV, induced by changes in Starling forces, venous return, BP, and HR

3. Mediastinum
Superior
Anterior
Middle
Posterior
Superior and anterior are continuous with each other; both may be referred to as the superior mediastinum

4. Superior Mediastinum Transverse thoracic plane
Aortic arch
Great Vessels of the Heart

5. Remnant of Ductus arteriosus
Ligamentum arteriosum

6. Usual Aortic Arch PatternLC RC LS RS BT
65% of all people

7. Aortic Arch Variations
left vert. a.
27% one BT with both CC exiting 5%
1.2% two BT

9. SVC
Vagus
Phrenic BC BC
SVC

10. Pulmonary Arteries and Veins

11. Trachea and Primary bronchi

12. Structure Order
Trachea BC PA
Aorta

13. Esophagus Function: Deglutition
Two sphincters: upper and lower esophageal sphincters (lower is physiological only)
Retropleural position (therefore, covered by adventitia)
Mucosa: stratified squamous with many mucus glands (esophageal glands)
Muscularis: changes from skeletal to smooth muscle

14. Bilobed organ that is largest in children, but begins to regress sharply at the onset of puberty (around age 11)
It is the site of T-cell lymphocyte production and produces hormones (such as, thymosin) that modifies their physiology
Thymus Gland

15. General Circulatory System
Cardiovascular
Consists of a closed system of vessels which transport blood
Two circuits: Systemic and Pulmonary
Arteries move blood away from the heart
Veins move blood toward the heart

16. Heart Development

17. Fetal Circulation

18. Selected Heart Defects

19. Heart as a Dual Pump
Cardiac muscle arranged as whorls that squeeze the blood
Twin pumps: systemic and pulmonary
Four chambers: 2 atria and 2 ventricles

20. Cardiac Muscle Cells

21. Cardiac Muscle Depolarization

22. Heart: Location

23. Heart in Relation to other Organs

24. Layers of the Heart and Pericardium

25. Heart: Anterior View
Transverse Pericardial sinus

26. Heart: Posterior View
Oblique Pericardial sinus

27. Heart: Internal Anatomy

28. Differences in Ventricular Wall

29. Most Common Coronary Arterial Pattern
Circumflex a.
L. Marginal a.
Ant. Desc. a. (LAD)
Post. Desc. a.
R. Marginal a.
Fig. 1.51

30. Coronary Variation Most people right dominant. 15% LCA dominant
(note: which branch gives rise to posterior descending a.determines dominance)
Single CA
Circumflex from right aortic sinus
(4% have an accessory coronary artery)

31. Fig b
12.66b.jpg
Angiogram showing coronary blockage (arrow)

32. Fig c
12.66c.jpg
Angioplasty catheter

33. Fig d
12.66d.jpg

35. Coronary Veins Fig. 1.52 Ant. Cardiac veins Great Cardiac v.
Coronary sinus
Small Cardiac v.
Middle Cardiac v.
Fig. 1.52

36. Major Cardiac Valves

37. Heart Valves cusps AV (tricuspid) sinus aortic valve (SL)
Nodule (corpara aranti)

38. Heart Murmurs
12.22.jpg

39. Diastole: Period of Ventricular Filling

40. Systole: Isovolumetric Contraction

41. Systole: Ventricular Ejection

42. Diastole: Isovolumetric Relaxation

43. Conduction System of Heart

44. Pacemaker Potential

46. ECG and electrical changes

47. Normal ECG

48. ECG
Normal Sinus Rhythm
Junctional Rhythm (AV node rhythm)

49. Second Degree Heart Block
Ventricular Fibrillation (V-fib)

50. Heart Sounds “Lub-dub”
Sound associated with valve closing producing turbulent blood flow

51. (ml/min)

52. Factors Affecting SV EDV affected by: ESV
Stroke Volume (SV) = End Diastolic Volume – End Systolic Volume (SV = EDV – ESV(ml/beat) )
In a healthy 70-kg man, EDV is approximately 120 mL and ESV is approximately 50 mL, giving a difference of 70 mL for the stroke volume.
EDV affected by:
Venous return which is dependent on venous tone, skeletal muscle pumps, etc.
ESV
As the heart fills it is stretched which allows for better overlap of the contractile proteins which will affect the force of contraction and the ESV (Starling’s Law of the Heart –increase preload (ventricular stretch) increases contraction force)
Increasing the force of contraction at any EDV will decrease the ESV and increase the SV (sympathetic stimulation and epinephrine)

53. Pericardial sac prevents over distension and loss of overlap; decrease performance of myocardium at high EDVs is due to disruption of fibers

54. Sympathetic Stimulation
Leads to increase HR
Increases in Ca++ release from SR, increase Ca++ through membrane and increase myosin crossbridge cycling
Increases force of contraction

55. Heart Rate Control Sinus Rhythm = normal SA node control
Autonomic Activity
Sympathetic (thoracic trunk) = accelerator (induces tachycardia)
Parasympathetic (vagus n.)= brake (induces bradycardia)
Hormones
epinephrine
Drugs -caffeine, nicotine, atropine, etc.

56. Cardiac Cycle

57. Posterior Mediastinum
Azygous v.
Thoracic duct
Intercostal a., v., & n.
Sympathetic trunk
Trachea
Vagus n.
Thoracic aorta
Lung root
Phrenic n.
Esophagus
Hemiazygous v.

58. Small Aortic Branches
Coronary
Bronchial a.
Esophageal
Intercostals

59. Azygous vein
Hemiazygous v.

60. Nerves of Post. Mediastinum

61. Thoracic Duct