Thorax: Mediastinum Overview Flashcards

1
Q

Mediastinum Superior Boundary

A
  • Superior thoracic aperture (thoracic inlet)
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2
Q

Mediastinum Inferior Diaphragm

A
  • Diaphragm
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3
Q

Mediastinum Anterior Boundary

A
  • Sternum and costal cartilages (costal pleura)
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4
Q

Mediastinum Posterior Boundary

A
  • Vertebral bodies of T1-12
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5
Q

Mediastinum Lateral Boundary

A
  • Mediastinal pleura
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6
Q

Transverse Thoracic Plane

A
  • Manubriosternal joint > T4/5 disc

- Divides superior (purple) and inferior (rest of the colors) mediastinum

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7
Q

Superior Mediastinum

A
  • Superior to transverse thoracic plane
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8
Q

Inferior Mediastinum

A
  • inferior to transverse thoracic plane

- Includes anterior, middle, and posterior mediastinum

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9
Q

Superior Mediastinum

A
  • Thoracic inlet to transverse thoracic plane

- Between manubrium and T1-4

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10
Q

Content of Superior Mediastinum

A
  • Thymus (most anterior)
  • Brachiocephalic veins (posterior to thymus)
  • SVC (superior portion)
  • Aortic arch
  • Brachiocephalic artery (trunk)
  • Left Subclavian artery
  • Left common carotid artery
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11
Q

Superior Mediastinum Nerves

A
  • Left and right vagus
  • Left recurrent laryngeal
  • Left and right phrenic
  • Cardiac plexuses
  • Trachea
  • Esophagus
  • Thoracic duct
  • Sternothyroid and sternohyoid muscles
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12
Q

Thymus

A
  • Lymphoid organ
  • Superior and anterior mediastinum
  • Can extend above thoracic inlet
  • Most anterior structure in the mediastinum
  • Mostly replaced by fat by adulthood
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13
Q

Trachea

A
  • Passes through thoracic inlet

- Begins and level of C6 and ends at sternal angle (not found in the inferior mediastinum)

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14
Q

Esophagus

A
  • Passes through thoracic inlet
  • Begins at level of C6, passes through diaphragm at level of T10
  • Between trachea and vertebral column
  • Also found in posterior mediastinum
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15
Q

Brachiocephalic Veins

A
  • Pass through thoracic inlet
  • Formed by union of jugular and subclavian veins (posterior to SC joint)
  • Blood from head, neck, upper extremity
  • Left is longer, more horizontal
  • Anterior to the aortic arch branches
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16
Q

Tributaries

A
  • IJV
  • Subclavian veins
  • Internal thoracic veins
  • Inferior thyroid vein(s)
  • Vertebral veins
  • Supreme (highest) intercostal vein
  • Accessory hemiazygos vein
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17
Q

Superior Vena Cava (Superior Portion)

A
  • Union of brachiocephalic veins

- Spans 1st > 3rd costal cartilage (also in the middle mediastinum)

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18
Q

Tributaries

A
  • Veins
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19
Q

Branches

A
  • Arteries
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20
Q

Azygous

A
  • Candy cane structure on the right side of the heart
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21
Q

Hemiazygous

A
  • Located on left side
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22
Q

Aorta

A
  • Ascending
  • Arch
  • Thoracic descending
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23
Q

Ascending Aorta

A
  • Middle mediastinum
  • Aortic valve to sternal angle
  • Branches: left and right coronary
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24
Q

Arch of the Aorta

A
  • Superior mediastinum
  • Begins and ends at sternal angle
  • Branches: brachiocephalic trunk, left common carotid artery, subclavian artery
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25
Q

Thoracic Descending Aorta

A
  • Posterior mediastinum

- Cover the branches later

26
Q

Nerves of the Superior Mediastinum

A
  • Vagus nerves

- Recurrent laryngeal nerves

27
Q

Vagus Nerves

A
  • Originate in the brainstem
  • Enter mediastinum posterior to the brachiocephalic vein
  • Medial to phrenic nerve
  • Enters posterior mediastinum and passes posterior to the root of the lung
  • Contributes fibers to the cardiac, pulmonary and esophageal plexuses
  • Branches in the superior mediastinum
  • Exit posterior mediastinum and enter abdomen through esophageal opening
28
Q

Branches in the Superior Mediastinum

A
  • Left recurrent laryngeal nerves

- Cardiac branches

29
Q

Right Recurrent Laryngeal Nerve

A
  • Loops around the right subclavian artery (not in mediastinum)
30
Q

Left Recurrent Laryngeal Nerve

A
  • Loops around the aortic arch

- Posterior (lateral) to the ligamentum arteriosum (remnant of fetal ductus arteriosus)

31
Q

Left/Right Recurrent Laryngeal Nerves

A
  • Both ascend between trachea and esophagus to innervate the larynx
  • Injury or compression can alter voice (hoarseness)
32
Q

Phrenic Nerves

A
  • Formed from C3,4,5
  • Passes posterior to subclavian vein, then enters superior mediastinum
  • Both nerves pass through middle mediastinum and pass anterior to the root of the lung
  • Between mediastinal pleura and fibrous pericardium
33
Q

Phrenic Motor Innervation

A
  • Diaphragm
34
Q

Phrenic Sensory Innervation

A
  • Central diaphragm
  • Pericardium
  • Mediastinal pleura
35
Q

Right Phrenic Nerve

A
  • Passes over pericardium over the right atrium

- Some branches passes through caval opening on the diaphragm

36
Q

Left Phrenic Nerve

A
  • Travels along fibrous pericardium over the left ventricle

- Pierces diaphragm

37
Q

Anterior Mediastinum

A
  • Between pericardium and parietal (coastal) pleura covering sternum/transversus thoracis muscle
38
Q

Content of Anterior Mediastinum

A
  • Thymus (infants and children)
  • Fat
  • Lymph vessels and nodes (anterior mediastinal nodes)
  • Branches/tributaries of internal thoracic artery/vein
  • Sternopericardial ligaments
39
Q

Sternopericardial Ligaments

A
  • Attach from pericardium to sternum

- Pass through anterior mediastinum

40
Q

Middle Mediastinum

A
  • Between ant/post borders of the pericardium

- Between mediastinal pleura laterally

41
Q

Middle Mediastinum Contents

A
  • Pericardium
  • Heart
  • Proximal end great vessels
  • Phrenic nerves
  • Pericardiophrenic vessels
42
Q

Pericardium

A
  • Closed sac

- Protects heart and prevents overdistension

43
Q

2 Layers of Pericardium

A
  • Fibrous pericardium

- Serous pericardium

44
Q

Fibrous Pericardium

A
  • Tough outer layer
  • Attached to central tendon of the diaphragm
  • Blends with connective tissue of great vessels
45
Q

Serous Pericardium

A
  • Formed by mesothelium – secretes serous fluid
  • Parietal layer
  • Visceral layer (epicardium)
46
Q

Parietal Layer of Serous Pericardium

A
  • Lines inside of fibrous pericardium
47
Q

Visceral Layer of Serous Pericardium (Epicardium)

A
  • Covers the heart
48
Q

Pericardial Cavity

A
  • Potential space between serous pericardium

- Contains small amounts of fluid

49
Q

Transverse Pericardial Sinus

A
  • Transverse passage between outflow and inflow vessels

- Provides access to clamping the aorta and pulmonary trunk

50
Q

Oblique Pericardial Sinus

A
  • Blind recess posterior to the heart base (left atrium)

- Between pulmonary veins

51
Q

Blood Supply of Pericardium

A
  • Pericardiophrenic artery & vein (from internal thoracic)
  • Coronary vessels supply visceral pericardium
52
Q

Sensory Innervation of the Pericardium

A
  • Phrenic nerve (C3-5)

- Visceral pericardium is supplied by autonomics

53
Q

Cardiac Tamponade

A
  • Buildup of fluid in the pericardial space that results in the compromised ventricular filling and hemodynamic compromise
  • Medical emergency
  • Causes Beck’s triad
54
Q

Pericardiocentesis

A
  • Aspiration of fluid from the pericardial space

- Infrasternal angle (subxiphoid) or left sterncostal or left 5th intercostal space (parasternal)

55
Q

Basic Anatomy of the Heart

A
  • Left and right atria
  • Left and right ventricles
  • Left and right AV valves
  • Aortic and pulmonary valves
56
Q

Great Vessels of the Heart

A
  • Superior Vena Cava
  • Inferior Vena Cava
  • Pulmonary Trunk/Arteries
  • Pulmonary Veins
  • Aorta
57
Q

Layers of the Heart

A
  • Endocardium
  • Myocardium
  • Epicardium
58
Q

Endocardium

A
  • Endothelium
59
Q

Myocardium

A
  • Thick myocardial muscle
60
Q

Epicardium

A
  • Visceral layer of serous pericardium