Superior & Posterior Mediastinum Flashcards Preview

Anatomy (Karen) > Superior & Posterior Mediastinum > Flashcards

Flashcards in Superior & Posterior Mediastinum Deck (18):
1

What is the course of the aorta?

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  • ascending aorta as it comes out of LV
    • gives rise to R & L coronaries
  • arch goes upwards, backwards to the left (superior mediastinum)
    • begins and ends at manubriosternal -- T4/T5
    • arches over:
      • L pulm artery
      • L pulm veins
      • L main bronchi
      • branching of pulmonary trunk (connected to it via ligamentum arteriosum)
  • becomes descending thoracic aorta
  • descends midline behind oesophagus and anterior to VC
  • enters diaphragm thru aortic hiatus between the crura @T12

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2

What are the major branches of the aorta?

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  • First brances are R & L coronares off ascending
  • Arch supplies head, neck, and upper limb
  • Brachiocephalic trunk: --> R subclavian & R carotid
  • L carotid
  • L subclavian

Descending thoracic aorta gives off:

  • posterior intercostal arteries
  • bronchial areteries @ hilum of lungs
  • oesophageal branches
  • minor pericardial branches

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3

What are the contents of the superior mediastinum?

Superficial to deep:

  • thymus (if present)
  • great veins
  • aortic arch + vagus and phrenic nerves
  • trachea
  • oesophagus
  • thoracic duct
  • L recurrent laryngeal nerve

4

What are the contents of the posterior mediastinum?

Superior posterior:

  • trachea
  • oesophagus
  • R & L recurrent laryngeal nerves
  • thoracic duct (on back of oesophagus)

Deep posterior:

  • descending thoracic aorta
  • oesophageus (vagal plexus on front, thoracic duct on back)
  • azygous vein
  • sympathetic trunks

5

What is the origin and course of the jugular veins?

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  • drain the head and neck
  • into subclavian vein (drains upper limb)
  • into brachiocephalic veins (@medial clavicle)
  • which join into SVC (@1st R costal cartilage)

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6

What is the origin and course of the subclavian veins?

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  • drain the upper limb
  • receive drainage from head and neck via IJVs
  • drain into brachiocephalic veins (@medial clavicles)
  • which form the SVC (@1st R costal cartilage)

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7

What is the origin and course of the brachiocephalic veins?

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  • drainage from IJV --> subclavians
  • subclavians branch @ medial clavicle
  • form SVC (@1st R costal cartilage)
  • R brachiocephalic is shorter and more vertical
  • L brachiocephalic crosses over to left (@1st R costal cartilage)

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8

What is the origin and course of the superior vena cava?

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  • Brachiocephalic veins join (@1st R costal cartilage)
    • drainaige from IJVs > subclavians > brachiocephalics
  • SVC enters peridcardium @2nd R costal cartilage
  • SVC enters RA @3rd R costal cartilage
  • venous return from head, neck, and upper limbs

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9

What is the azygous system of veins?

  • ascends the R vertebral column arching over the R lung root
  • enters SVC posteriorly @ 2nd R costal cartilage
  • venous return from
    • posterior intercostal veins
    • thoracic walls
    • everything in thorax except heart
    • draining descending aorta supply:
      • bronchial, oesophageal, pericardial veins

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10

What is the course of the trachea?

  • extends through superior mediastinum at T4/T5
  • splits into R & L main bronchi

11

What is the course of the oesophagus?

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superior mediastinum:

  • posterior to trachea
  • descends midline

posterior mediastinum:

  • passes left into diaphragm thru oesophageal hiatus @ T10
  • in front of descending aorta and VC

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12

What is the course of the thoracic duct?

  • begins at cisterna chyli
    • distal end, drains lymph from intestinal trunk and lumbar trunks
    • posterior to abdominal aorta on anterior L1 & L2
  • collects all lymph from below the diaphragm (pelvis, abdomen, lower limbs)
  • always on the back of the oesophagus, anterior to aorta & VC
  • ascends upwards and empties into junction at L IJV and L subclavian vein

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13

What is the course of the R vagus nerve?

  • cranial nerve
  • runs in carotid sheath (int. carotid and jugular vein)
  • runs medially, alongside trachea (phrenic lateral)
  • behind lung root (phrenic anterior)
  • to anterior oesophagus
    • joins w/L vagus to form an oesophageal nerve
  • gives off R recurrent laryngeal nerve @ R subclavian artery
    • hooks around the artery and ascends the right tracheoesophageal groove to innervate larnyx

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14

What is the course of the L vagus nerve?

  • cranial nerve
  • runs in carotid sheath (int. carotid and jugular vein)
  • lateral to aortic arch (can't get to trachea)
  • behind lung root (phrenic anterior)
  • onto anterior oesophagus
    • meets R vagus to form an oesophageal nerve
  • gives off L recurrent laryngeal nerve at arch of aorta
    • hooks around ligamentum arteriosum
    • under arch of aorta
    • back to laryngeal structures in the L tracheoesophageal groove

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15

What is the course of the phrenic nerve?

  • branch of cervical plexus (ventral rami C3, 4, 5)
  • descends on scalenus anterior
  • passes between subclavian artery and vein
  • passes anterior to the lung root (bronchi & pulm vessels)
  • pierces and innervates the diaphragm
    • R thru caval orifice @ T8
    • L into muscle of L dome
  • R is lateral to venous structures (SVC, RA, IVC)
  • L is lateral to arterial structures (aortic arch, LV)

 

Innervation:

  • motor: abdominal surface of diaphragm
  • sensory: mediastinal & diaphragmatic pluera, pericardium

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16

What are the borders of the superior mediastinum?

  • above line from mediasternal junction to T4/T5
  • between the L & R pleural cavities

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17

What are the borders of the inferior mediastinum?

  • below mediasternal junction -- T4/45
  • middle contains heart
    • divides inferior mediastinum into anterior and posterior mediastinum

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18

What can be a cause of dysphasia (difficulty swallowing)?

4 aortic branches (i.e. no brachiocephalic trunk)

traps trachea & oesophageus in centre

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