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Flashcards in mediastinum and imaging : Deck (47)
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1
Q

what is the mediastinum ?

A

Thick midline partition that separates the two pleural cavities.

2
Q

what are the boundaries of the mediastinum?

A

superior : superior thoracic aperture inferior :inferior thoracic aperture anterior :manubrium of sternum posterior : thoracic vertebrae

3
Q

function of the mediastinum?

A
  • allows the passage of structures through from one body region to another - connects thoracic organs to other body regions
4
Q

recap what is the thoracic inlet?

A
  • consists of the 1st thoracic vertebrae - 1st ribs - manubrium - the great vessels - oesophagus - trachea - nerves - lymphatics
5
Q

where does the apex of the lung sit?

A
  • 3cm above the clavicle in the neck
6
Q

where does the right phrenic nerve sit? where does the thoracic duct and azygos vein sit?

A
  • T8 - T12
7
Q

where is the division of the mediastinum?

A
  • transverse plane between the sternal angle ( CC2) and T4/5
8
Q

what does the mediastinum split into?

A
  • superior - above sternal angle - inferior - below sternal angle anterior - : anterior to heart in pericardial sac middle - heart in pericardial sac posterior - posterior to pericardial sac and diaphragm
9
Q

what are the contents of the mediastinum?

A
  • trachea (from C6 to T4) - oesophagus C6 pierces diaphragm at T10 - heart and pericardium - thoracic duct - lymphathic drainage - nerves - great vessels
10
Q

label a thoracic inlet?

A
11
Q

what does the superior mediastinum contain?

A
  • thymus
  • great veins
  • SVC
  • phrenic nerves
  • main lymphathic trunks
  • vagus nerve
  • great arteries
  • trachea
  • main bronchi
  • upper oesophagus
12
Q

label a superior mediastinum:

A
13
Q

what does the posterior mediastinum contain?

A
  • oesophagus
  • descending aorta
  • thoracic duct
  • azygos venous system
  • —Posterior mediastinal lymph nodes
  • —Thoracic sympathetic trunks
  • —Splanchnic nerves
14
Q

what is the passage of the oesophagus?

A
  • begins at C7 vertebra
  • •Enters superior thoracic inlet into superior mediastinum
  • enters the posterior mediastinum
  • at T7 it deviates to the left and inclines anteriorly so it passes in front of the descending thoracic aorta
  • passes through the diaphragm at T10
15
Q

what are the constrictions of the oesophagus?

A
  • the junction between the pharynx and oesophagus
  • where the oesophagus passes the arch of the aorta
  • where the oesophagus is compressed by left main bronchus
  • at the oesophageal hiatus (the diaphragm)
16
Q
A
17
Q

label the passage of the oesophagus:

A
18
Q

what is the superior vena cava made from?

A
  • formed by the asymmetric union of the left and right brachiocephalic veins
  • —Each brachiocephalic vein – formed by Internal jugular vein + subclavian vein.
19
Q

what does brachiocephalic actually mean?

A

brachio - arm

cephalic - head

therefore drains venous blood from brain and arm

20
Q

label the azygos venous system

A

refer to netters 3- 15

21
Q

what is the function of the azygos veins?

A
  • drains the posterior walls of the chest and the upper abdomen

and also the posterior mediastinal organs

22
Q

what do the hemiazygos veins do?

A

—Accessory hemiazygos (upper) + hemiazygos (lower) veins on left cross thoracic vertebral bodies to join single azygos vein on right

23
Q
A
24
Q

is the azygos symmetrical or asymmetrical?

A

asymmetrical

25
Q

what is the thoracic duct?

A
  • the largest lymphatic vessel
  • begins on the level of T12
  • it enters the thorax through the diaphragm at T12
  • —At T5, it crosses the midline to the left side and enters the superior mediastinum
26
Q

what are the great arteries?

A

—Ascending aorta – middle (origin at the left 3rd CC)

—Arch of the aorta – superior ( called this from the 2nd CC)

—Descending aorta - posterior ( starts at T4)

—

27
Q

label the arteries of the thoracic aorta?

A

refer to netters 3- 14

28
Q

where is the aorta in regard to the trachea and left main brainchus

A
  • the aortic arch arises anterior to the trachea and arches over the left main bronchus
29
Q

where does the trachea lie?

A

the trachea lies behind and between the brachiocephalic and left common carotid artery

30
Q

where are the phrenic nerves formed?

A

in the cervical plexus from C3 C4 C5

31
Q

where does the motor phrenic nerve innervate

where do the sensory phrenic nerves innervate

A

motor - diaphragm

sensory - —central tendon of the diaphragm

mediastinal pleura

pericardium

the peritoneum of the central diaphragm

32
Q

what surfaces does the right phrenic nerve run on to reach the diaphragm ?

A

lies on the surface of :

  • right brachiocephalic nerve
  • superior vena cava
  • right side of the heart and the pericardium
33
Q

what is the general rule of the positioning of the phrenic nerve and the vagus nerve?

A

phrenic nerve is anterior to the lung root

the vagus nerve is posterior to the lung root

34
Q

where are the vagus nerves positioned?

where are vagus nerves compared to common carotids?

where does the left vagus nerve pass?

when does the left phrenic nerve pass the vagus?

A
  • vagus nerves are posterior to the lung roots and form plexus following the oesophagus into the abdomen giving branches to heart and lungs on the way
  • the vagus nerves are lateral to the common carotids
  • the left vagus nerve passes anterior to the aortic arch
  • the left phrenic nerve crosses the vagus to cross the aortic arch more anteriorly
35
Q

where do the left vagus phrenic and vagus nerves sit?

A
  • Cross arch of aorta
  • —Left phrenic descends in front of lung root
  • Left vagus crosses behind root lung gives off left recurrent
36
Q
A
37
Q

how does the laryngeal nerve sit?

A
  • it recurs around the ligamentum arteriosum and the aortic arch
  • it then breaks up into many branches around the oesophagus
38
Q
A
39
Q

where does the right vagus nerve lie?

A
  • it lies on the trachea
  • it crosses behind the lung root
40
Q

what happens to the recurrent laryngeal branch?

A
  • it recurs back around the right subclavian artery
  • it also breaks up into branches on the oesophagus
41
Q
A
42
Q

what does the vagus nerve provide parasympathetic control to?

A

control of smooth and cardiac muscle and the glands of gut and airways

43
Q

where does the vagus nerve act as a sensory nerve?

A
  • the guts and the lungs
44
Q

what is the recurrent laryngeal nerve?

A
  • it is not parasympathetic
  • it runs back up the neck to supply most of the skeletal muscles of the larynx
45
Q

why is the recurrent laryngeal nerve important?

A
  • it contributes to the muscles allowing us to speak
  • in neck surgery if these nerves are damaged then it may cause of voice which is called paralysis
46
Q

label this diagram

A
47
Q
A