Mediastinal Structures Flashcards

1
Q

What is the mediastinum?

A

The partition between the two pleural cavities and lungs

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2
Q

What are the two subdivisions of the mediastinum?

A

Superior mediastinum and inferior mediastinum

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3
Q

What are the three divisions of the inferior mediastinum?

A

Anterior

middle and posterior mediastinum

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4
Q

Where is the superior mediastinum?

A

Bounded anteriorly by the manubrium of the sternum and posteriorly by the bodies of T1 to T4 vertebrae

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5
Q

What are the contents of the superior mediastinum?

A

Thymus
Left brachiocephalic vein
Right brachiocephalic vein
Superior vena cava

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6
Q

How are the veins of the superior mediastinum located?

A

The two brachiocephalic veins unite to form the superior vena cava

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7
Q

What is the difference in shapes between the left and right brachiocephalic vein?

A

The left vein is longer and more oblique

The right is more vertical

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8
Q

Where are the aortic branches located?

A

Superior mediastinum

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9
Q

What are the three aortic branches?

A

Left common carotid
Left subclavian
Brachiocephalic

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10
Q

Where does the phrenic nerve originate?

A

C3-C5

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11
Q

Where is the phrenic and vagus nerves related to the root of the lung?

A

Phrenic nerve is anterior

Vagus nerve is posterior

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12
Q

Where is the left recurrent laryngeal nerve?

A

Located in the superior mediastinum

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13
Q

Where is the anterior mediastinum located?

A

Posterior to body of sternum and attached costal cartilages, anterior to heart and pericardium

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14
Q

What are the contents of the anterior mediastinum?

A

Fat
Remnants of thymus glands
Anterior mediastinal lymph nodes

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15
Q

Where is the location of the middle mediastinum?

A

Between anterior and mediastinum and posterior mediastinum

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16
Q

What are the contents of the middle mediastinum?

A
Heart and pericardium 
Beginning or termination of great vessels 
Phrenic nerves 
Pericardiacophrenic vesels 
Lymph nodes
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17
Q

Where is the posterior mediastinum located?

A

Posterior to heart and pericardium - anterior to vetebrae T5-T12

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18
Q

What does the posterior mediastinum contain?

A
Contains 4 tubular structures 
Oesphagus 
Thoracic aorta
Thoracic duct 
Azygous venous system
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19
Q

What is the thoracic aorta?

A

Continuation of the aortic arch at lower border T4

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20
Q

What is the route of the thoracic aorta?

A

Courses downward on left side of, then in front of the vertebral column
Passes through the aortic hiatus of diaphragm at level of T12 vertebra to enter abdominal cavity

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21
Q

What are the two main branches of the thoracic aorta?

A

Parietal branches and visceral branches

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22
Q

What is meant by parietal?

A

The wall

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23
Q

What is meant by visceral?

A

to the organ

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24
Q

What makes up the parietal branches of the thoracic aorta?

A

Nine pairs of the posterior intercostal arteries

One pair subcostal artery

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25
What makes up the visceral branches of the thoracic aorta?
Bronchial branches: one or two for each lung | Oesphageal and pericardial branches
26
What forms the brachiocephalic vein and where?
Formed by the union of internal jugular and subclavian veins posterior to the sternoclavicular joint
27
What is the angle of union of the brachiocephalic veins known as?
Venous angle
28
What forms the superior vena cava and where?
Formed by the union of right and left brachiocephalic veins behind the right sternocostal joint of the first rib
29
Where does the superior vena cava run?
Runs vertically down on the right of the acending aorta
30
Where does the azgous vein join the superior vena cava?
Level of sternal angle
31
Where does the SVC enter the right atrium?
Enters at the lower border of the third right sternocostal joint
32
What is the role of the SVC?
Collects blood from veins of upper half of the body
33
What does the azgos vein begin as?
Continuation of right ascending lumbar vein
34
How is the azygos vein formed?
Formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebrae
35
What are the two tributaries of the azgous vein?
Hemiazygous vein | Accessory hemiazygous
36
Where does the thoracic duct begin?
Begins in front of L1 as a dilated sac
37
What is the dilated sac that forms the thoracic duct known as?
Cisterna chyli
38
How is the dilated sac formed?
Joining of left and right lumbar trunks and intestinal trunk
39
Where does the thoracic duct travel?
Enters the thoracic cavity by passing through the aortic hiatus of the diaphragm and ascends along the front of the vertebral column between thoracic aorta and azygous vein
40
What happens to the thoracic duct at T5?
It veers to the left
41
What happens to the thoracic nerve at the root of the neck?
Turns laterally and arches fowards and descends to enter the left venous angle
42
What happens if there is a hole in the thoracic duct?
Forms a chylothorax
43
What is the role of the thoracic duct?
Drains lymph from lower limbs, pelvic cavity, abdominal cavity, left side of thorax, and left side of the head, neck and left upper limb
44
What forms the right lymphatic duct?
Formed by the union of the right jugular, subclavian and bronchomedastinal trunks
45
How does the right lymphatic duct end?
Ends by entering the right venous angle
46
Where does the phrenic nerve run?
Runs posterior to the subclavian vein
47
What happens when the phrenic nerve enters the thorax?
Runs anterior to the root of the lung and into the pericardium between the fibrous and parietal layers
48
What do the phrenic nerves supply?
Supply motor fibres to the diaphragm and sensory fibrous pericardium medistinal pleura and diaphragmatic peritoneum
49
Where does the left vagus nerve enter the thoracic inlet?
Between the left common carotid and left subclavian arteries, posterior to the left brachiocephalic vein
50
What happens to the left vagus nerve as it crosses the aortic arch?
The left recurrent laryngeal nerve branches off | The LVN passes posterior to the left lung
51
What does the LVN form?
Anterior oesophaegeal plexus Forms anterior vagal trunk at the hiatus where it leaves thorax and passes into abdominal cavity, then divides anterior gastric and hepatic branches
52
Where does RVN enter the thoracic inlet?
The right side of the trachea
53
Where does the RVN travel?
downward posterior to right brachiocephalic vein and superior vena cava passes posterior to right lung root
54
What does the RVN form?
Posterior oesophageal plexus | Posterior vagal trunk
55
Where is the posterior vagal trunk formed and where does it travel
Formed at the oesophagul haitus | Leaves thorax and passes into abdominal cavity and then divides in to posterior gastric and celiac branches
56
What is the path of the recurrent laryngeal nerve?
Right one hooks around right subclavian artery and left one hooks around the aortic arch Both ascend in tracheo-oesphageal groove
57
What do the recurrent laryngeal nerves innervate?
Laryngeal mucosa below fissure of glottis | All laryngeal muscles exceot cricothyroid
58
What is the oesophagus?
A muscular tube passing through between the pharynx in the neck and stomach in the abdomen
59
Where does the oesophagus begin?
Begins at the inferior broder of the cricoid cartilage, opposite vertebrae CVI
60
Where does the oesophagus end?
Ends at the cardiac opening of the stomach opposite T11
61
Where does the oesophagus travel?
Oesophagus descend on the anterior aspect of the bodies of the vertebrae (midline position) Approaches the diaphragm, it moves anteriorly Passes through the oesphageal hiatus ( an opening in the muscular part of the diaphragm, at vertebral level T10)
62
What are the four locations where the muscular tube that can be compressed or narrowed?
Pharynx Arch of aorta Left main bronchus Oesophageal hiatus
63
What are the three parts of the oesphagus?
Cervical Thoracic Abdominal
64
What makes up the sympathetic trunk?
Thoracic viscera (T1-T4) Greater splanchnic nerve Lesser splanchic nerve Least splanchnic nerve
65
What level is the caval opening and what structures are present within it?
T8 | inferior vena cava and some branches of the right phrenic nerve
66
What level is the oesphageal hiatus and what structures are present within it?
T10 | oesophagus, the anterior and posterior vagal trunks, and some small oesphageal arteries
67
What level is the aortic hiatus and what structures are present within it?
T12 | aorta, the azygos vein and the thoracic duct
68
What are the structures within in the two lesser aperture of the right crus?
Greater and lesser right splanchnic nerves
69
What are the structures of the three leser aperature of left crus?
Greater and lesser left splanchnic nerevs and the hemiazygos vein
70
What are the structures that go through the opening behind the diagram, under the medial acruate ligament
Sympathetic trunk and the least splanchic nerves
71
What are the structures that pass through the opening anterior to the diaphragm, just deep to the ribs?
Superior epigastric vessels
72
What are the structures that pass through the diaphragm?
inferior vena cava some branches of the right phrenic nerve oesophagus the anterior and posterior vagal trunks some small oesophageal arteries the aorta the azygos vein the thoracic duct greater and lesser right splanchnic nerves greater and lesser left splanchnic nerves the hemiazygos vein sympathetic trunk the least splanchnic nerves on both sides sympathetic trunk the least splanchnic nerves on both sides
73
Where do the upper 6 pairs of anterior intercostal arteries arise from?
Internal thoracic artery
74
Where do the 7th, 8th and 9th pairs of anterior intercostal arteries arise from?
Musculophrenic artery
75
What is the origin of the internal thoracic artery?
From the first part of the subclavian artery
76
Where does the internal thoracic artery terminate?
Opposite the sixth intercostal space by dividing into superior epigastric and musculophrenic arteries
77
What are the 8 branches of the internal thoracic artery?
1. Pericardial branches. 2. Pericardiaco-phrenic artery. 3. Mediastinal branches. 4. Sternal branches. 5. Perforating branches for the mammary gland. 6. Anterior intercostal arteries (upper 6 spaces). 7. Superior epigastric artery. 8. Musculo-phrenic artery.
78
What forms the internal thoracic vein and where is it formed?
Formed by the union of the two venae comitantes of the internal thoracic artery Behind the third costal cartilage
79
Where does the internal thoracic vein ascend and where does it terminate?
Ascends close to the artery and terminates at the corresponding innominate vein
80
What does each posterior intercostal artery give and where does this structure run?
Gives a collateral branch and is runs over the upper border of the rib below
81
Were do the upper two posterior intercostal arteries come from?
superior intercostal artery from the second part of the subclavian artery
82
What do the posterior arteries 3-11 come from?
Descending thoracic aorta