Mediastinum

Question 1

describe the Plane of Ludwig/transthoracic plane

Answer 1

• this plane divides the mediastinum into a superior and inferior portion
• anteriorly
  
  • angle of Louis (sternomanubrial angle)
  • 2nd costal cartilage
• posteriorly
  
  • T4/5

Question 2

name the 3 branches of the aortic arch

Answer 2

1. brachiocephalic
   
   • r. subclavian a.
   • r. common carotid a.
2. left common carotid a.
3. left subclavian a.

Question 3

name the nerves of the superior mediastinum

Answer 3

• vagus nerve
  
  • travels along the common carotid a.
• recurrent laryngeal nerves
  
  • left associated with arch of aorta
  • right associated with subclavian a.

Question 4

name the boundaries and divisions of the inferior mediastinum

Answer 4

• superior: transthoracic plane
• inferior: diaphragm
• anterior: body of sternum
• posterior: vertebrae
• division:
  
  • anterior
  • middle
  • posterior

Question 5

describe the anterior mediastinum

Answer 5

• bordered anterior by the sternum and posterior by the pericardium
• contents:
  
  • thymus in younger individuals
  • replaced by fat tissue as an individual ages

Question 6

describe the middle mediastinum

Answer 6

• boundaries: bounded by the fibrous and parietal layer of serous pericardium on all sides
• contents: heart and the roots of the great vessels
  
  • ascending aorta
  • SVC
  • pulmonary trunk
  • pulmonary veins

Question 7

describe the posterior mediastinum

Answer 7

• boundaries: anterior = pericardium, posterior = vertebrae
• contents:
  
  • esophagus
  • thoracic duct
  • sympathetic chain
  • Azygos venous system
  • descending thoracic aorta
  • vagus nerve

Question 8

describe the arterial supply/venous drainage/innervation/lymphatic drainage of the thoracic portion of the esophagus

Answer 8

• arterial supply: thoracic aorta & bronchial arteries
• venous drainage: esophageal veins-azygos hemiazygos veins
• innveration: vagus-esophageal plexus, sympathetic trunks
• lymphatic drainage: thoracic duct-posterior mediastinal nodes

Question 9

describe the arterial supply/venous drainage/innervation/lymphatic drainage of the abdominal portion of the esophagus

Answer 9

• arterial supply: left gastric artery and left inferior phrenic
• innervation: vagal trunks, greater splanchnic nerves
• venous drainage: left gastric vein
• lymphatic drainage: left gastric nodes

Question 11

name 3 potential sites of esophageal constrictions

Answer 11

• junction with the pharynx: C6
• crossed by the left bronchus and arch of aorta: T4/5
• passage through the diaphragm: T10

Question 12

describe the thoracic duct

Answer 12

• largest and most prominent lymphatic vessel in body
• carries lymph from entire body (except right head and neck, right upper limb and right thorax)

Question 13

describe the path of the thoracic duct

Answer 13

• starts in the abdomen as the cisterna chyli
• passes through the diaphragm with the aorta
• travels between the azygos vein on the right and aorta on the left
• crosses to the left at the transthoracic plane
• drains into the junction between the right brachiocephalic and subclavian veins
• receives lymph from the left side of the thorax along the way

Question 14

name ways the thoracic duct can be injured

Answer 14

• internal jugular vein catherization
• operating surgery (esphagectomy)
• penetrating trauma
• pathologic processes affecting lungs, great vessels, esophagus, spine, lymph nodes