Heart & Mediastinum

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  1. What plane divides the mediastinum into superior / inferior parts?
    • Transverse thoracic plane (T4/5 IV disc)
    • Inferior mediastinum subdivided
    • (anterior / middle / posterior)
  2. Supine position of mediastinum
    • aortic arch superior to TTP (T4/5 IV disc)
    • tracheal bifurcation transected by TTP
    • central tendon lies at xiphisternal junction (T9)
  3. Standing position of mediastinum
    • aortic arch transected by TTP (T4/5 IV disc)
    • central tendon may fall to xiphoid process (T9/10 IV disc)
  4. Contents of superior mediastinum (anterior to posterior)
    • Thymus
    • SVC
    • Brachiocephalic vv.
    • Aortic arch (BCT / LCC / LScl)
    • Vagus / Phrenic nn.
    • Cardiac nerve plexus
    • L. Recurrent Laryngeal n.
    • Trachea
    • Esophagus
    • Thoracic duct
    • Prevertebral mm.
  5. Contents of anterior mediastinum
    • Remnants of thymus
    • Lymph nodes
    • Fat & CT
  6. Contents of middle mediastinum
    • Pericardium
    • Phrenic nn.
    • Heart / cardiac plexus
    • Roots of great vessels
    • Azygos arch
    • Main bronchi
    • Tracheobronchial lymph nodes
  7. Contents of posterior mediastinum
    • Thoracic aorta
    • Thoracic duct
    • Tracheobronchal LN
    • Azygos / Hemiazygos vv.
    • Esophagus
    • Esophageal plexus
    • Sympathetic trunks
    • Splanchnic nn.
    • Vagus nn.
  8. What structures pass w/in space between pericardial sac and visceral pleura?
    • Pericardiacophrenic aa.
    • Pericardiacophrenic nn.
    • Phrenic n.
  9. Organization of Pericardium
    Outer layer = fibrous pericardium

    Inner layers = serous pericardium (double layer visceral & parietal)
  10. Where does the transverse pericardial sinus lie?
    • Anterior to SVC
    • Posterior to Aorta & Pulmonary Trunk

    • Continuous from left to right sides of heart
    • (oblique pericardial sinus = blind pouch)
  11. Pericardial Vasculature
    • Pericardiacophrenic a.
    • (branch of int. thoracic a.)

    • Pericardiacophrenic vv.
    • (dumps into brachiocephalic vv.)
  12. Innervation of Pericardium
    Phrenic n. (C3-C5)

    Somatic only
  13. Relationship of structures in middle mediastinum
    phrenic n. passes anterior to root of lung

    vagus n. passes posterior to root of lung

    pericardiacophrenic vessels & phrenic n. superficial to fibrous pericardium
  14. Fibrous skeleton of heart
    4 annuli fibrosi (fibrous rings) fuse together

    • CT skeleton separates musculature of atria from ventricles
    • (attachment for valves / myocardial fiber bundles)
  15. Innervation of Heart
    • Sympathetics
    • - postganglionic fibers (cervical ganglia) -> cardiac plexus
    • - adrenergic (norepinephrine; increase HR / force)
    • - visceral afferents carry pain

    • Parasympathetics
    • - vagus n.
    • - cholinergic (ACh; decrease HR / force / constrict BV)
  16. Where is the SA node located?
    junction of SVC & superior crista terminalis
  17. Where is the AV node located?
    • posteroinferior region of interatrial septum
    • (near orifice of coronary sinus)
  18. Where do the branches of the AV node divide?
    junction of membranous / muscular parts of interatrial septum
  20. Venous drainage of Heart
  21. Lymphatic drainage of Heart
    lymphatics form network adjacent to endo/epicardium

    efferent vessels drain along coronary aa. empty into tracheobronchial nodes (lower end of trachea)
  22. What is the function of the thymus?
    • Produces lymphocytes
    • Gradually degrades post-puberty (replaced by fat)
  23. Blood supply to the thymus
    • Internal thoracic aa.
    • Superior thyroid aa.
  24. Lymphatic drainage of the body
    • 3/4 = thoracic duct (left)
    • 1/4 = r. lymphatic duct
  25. Brachiocephalic veins
    • Formed by subclavian / internal jugular vv.
    • L. BCV is 2x longer than R. BCV
    • R/L BCV unite to form SVC (1st costal cartilage)
  26. R. Brachiocephalic v. receives lymph from...
    R. Lymphatic Duct (1/4)
  27. L. Brachiocephalic v. receives lymph from...
    Thoracic Duct (3/4)
  28. Brachiocephalic Trunk
    • Most anterior branch of aortic arch
    • - Posterior to L. BCV
    • - Anterior to trachea

    Divides into RCC / RScl
  29. Left Common Carotid Artery
    • Middle branch of aortic arch
    • Ascends post. to left sternoclavicular joint (into neck)
  30. Left Subclavian Artery
    • Most posterior branch of aortic arch
    • Ascends lateral to trachea
  31. Where do the phrenic nn. lie as they run into thorax?
    Lie on anterior surface of anterior scalene mm.
  32. Where do the vagus nn. lie as they run into thorax?
    Lies deep to carotid sheath b/w common carotid aa. & internal jugular vv. in neck
  33. Path of R. recurrent laryngeal n.
    • branches from r. vagus n. (anteromedial to RScl a.)
    • wraps posteriorly around RScl a.
    • ascends in tracheoesophageal groove
    • innervates all intrinsic muscles of larynx except cricothyroid m.
  34. Path of L. recurrent laryngeal n.
    • branches from l. vagus n. (anteromedial to aortic arch)
    • wraps around aortic arch (posterolateral to ligamentum arteriosum)
    • ascends similar to r. recurrent laryngeal
  35. Origin of superior phrenic aa.
    Inferior part of thoracic aorta
  36. Esophageal nerve plexus
    • Anterior vagal trunk arises from L. vagus n.
    • Posterior vagal trunk arises form R. vagus n.

    "hang a right"
  37. Innervation to esophagus
    • Vagus n. (motor / secretomotor / sensory)
    • Sympathetics (vasomotor)

    • Superior esophagus
    • - recurrent laryngeal nn.
    • - sympathetics (middle cervical ganglion)

    • Inferior esophagus
    • - esophageal plexus
    • - parasympathetics (vagus nn.)
    • - sympathetics (gray rami upper 4 thoracic ganglion)
  38. Main blood supply to esophagus
    Esophageal branches of thoracic aorta
  39. Thoracic duct
    Begins at cisterna chili

    Empties on left side at junction of internal jugular / L. subclavian vv.
Card Set
Heart & Mediastinum
Exam 3
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