Mediastinum Flashcards Preview

LSS 1 - Thorax anatomy, Respiratory and Circulatory system > Mediastinum > Flashcards

Flashcards in Mediastinum Deck (46)
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1
Q

What is the mediastinum?

A

Thick midline partition spearating the 2 pleural cavities

2
Q

How far does the mediastinum extend?

A

From superior thoracic aperture to inferior thoracic aperture and between sternum ant and thoracic vertebrae post

3
Q

What is the mediastinum for?

A

Acts as a conduit for structures that pass from one body region to the other and for tructures that connect thoracic organs to other body regions

4
Q

What are the main contents of the mediastinum?

A

Trachea (larynx to bifurcation into principal bronchi), oesophagus (pharynx thru diaphragm at T10), heart, pericardium, thoracic duct, nerves, great vessels

5
Q

How is the mediastinum divided?

A

Superior (above sternal angle), Inferior (below sternal angle), Anterior (to heart), Middle (heart), Posterior (to heart and diaphragm)

6
Q

What are the contents of the superior mediastinum from anterior to posterior?

A

Thymus, Phrenic Nerves, Braciocephalic veins, thoracic duct, Vagus nerves, great arteries, Trachea and main bronchi, Upper oesophagus, left recurrent laryngeal nerve

7
Q

At what level does the trachea end?

A

T4-5 where the 2nd costal cartilage attaches - Sternal angle

8
Q

What are the great arteries present in the mediastinum?

A

Left common carotid, left subclavian and right brachiocephalic trunk (splits into right subclavian and common carotid)

9
Q

What are the great veins?

A

SVC (enters right atrium from above) and IVC (enters right atrium from below through central tendon of the diaphragm)

10
Q

Where is the phrenic nerve embedded?

A

In the pericardial sac

11
Q

At what level is the aortic arch?

A

The top is at the sternal angle

12
Q

What does each brachiocephalic vein branch off into?

A

Internal jugular (from head) and subclavian( from upper limbs) vein

13
Q

How do the brachiocephalic veins (BCV) join to become the svc?

A

Left BCV crosses from left to right, posterior to the manubrium, joining the R BCV

14
Q

Where does each brachiocephalic vein branch sit?

A

Underneath each sternoclavicular joint

15
Q

In which part of the mediastinum are the arch, ascending and descending aorta?

A

Arch: superior, Ascending: middle and descending: posterior

Asc and Desc are both in the inferior mediastinum

16
Q

What are the first branches of the ascending aorta?

A

Right and left coronary arteries

17
Q

What branches from the aortic arch?

A

Brachiocephalic trunk, left common carotid and left subclavian

18
Q

How does the aorta relate to the airways?

A

Arch rises anterior to trachea and over the left main bronchus at the lung root

19
Q

How does the trachea relate to the great arteries?

A

It lies behind and between the brachiocephalic and the common carotid/subclavian

20
Q

How are the common carotid arteries distributed?

A

They divide into external and internal carotids in the neck, vertebral arteries come from subclavian

21
Q

How does the blood flow to the lungs work?

A

Comes out from right ventricle, carrying deO2 blood via pulmonary arteries to lungs

22
Q

How does the foetus bypass the lungs?

A

Ductus arteriosus which is a structure that connects the pulmonary trunk to the aortic arch - after foetal life called ligamentum arteriosum

23
Q

What are the contents of the posterior mediastinum?

A

Oesophagus, descending aorta, thoracic duct, azygos venous system, posterior mediastinal lymph nodes, thoracic sympathetic trunks, splanchnic nerves (ignore)

24
Q

What is the structure of each level of the oesophagus?

A

Begins at C7, ends at T11, bends anteriorally at T7 deviating to the left, passes through diaphragm at T10 and is constricted at 4 places

25
Q

Where is the oesophagus constricted?

A

Junction of oesophagus with pharynx, Where oesophagus crossed by aortic arch, where oesophagus is compressed by left main bronchus and at oesophageal hiatus

26
Q

Why is the oesophageal hiatus important?

A

It prevents stomach acid from coming back up and destroying the mucous layer present in the oesophagus

27
Q

How is the oesophagus delivered blood?

A

Via the oesophageal branches from the descending aorta

28
Q

What is the azygos venous system?

A

It drains the posterior wall of chest, upper abdomen and posterior mediastinal organs

29
Q

How does the azygos venous system work?

A

Major azygos vein on RHS, with hemiazygos (lower) and accessory hemiazygos (upper) draining into it from the LHS, crossing over thoracic vertebral bodies

30
Q

Where is the azygos vein positioned?

A

Arches over right lung root to enter SVC, above the right atrium

31
Q

What nerves are present in the mediastinum?

A

Phrenic nerves - C3-5, Vagus nerves (CNX) and sympathetic trunks

32
Q

Where are the phrenics located?

A

Anterior to lung roots and cross pericardium to diaphragm

33
Q

Where are the vagus nerves located?

A

Posterior to lung roots, forming plexus following oesophagus to abdomen, branching out to lungs and heart on the way

34
Q

Where do the sympathetic trunks lie?

A

Each side of the posterior meiastinum

35
Q

What do the phrenic nerves do?

A

Motor to diaphragm and sensory to central tendon of diaphragm, parietal pleura, pericardium, peritoneum of central diaphragm

36
Q

How does the phrenic nerve reach the diaphragm?

A

It lies on the surface of the right brachiocephalic vein, SVC and RHS of heart and pericardium - in front of lung root

37
Q

How are the great arteries related to the main nerves?

A

Vagus are lateral to common carotids, left vagus passes anterior to aortic arch, left phrenic crosses vagus to cross aortic arch more anteriorly

38
Q

How does the left phrenic nerve move down into thorax?

A

Descends in front of lung root

39
Q

How does the left vagus descend into thorax?

A

Left vagus crosses behind lung root and gives off left recurrent laryngeal nerve which recurs around ligamentum arteriosum an aortic arch, then breaks into many branches around the oesophagus

40
Q

How does the right vagus nerve descend into thorax?

A

It lies on trachea, crosses behind lung root, recurrent laryngeal recurs around subclavian artery and breaks up into branches on oesophagus

41
Q

Where do the vagus nerves branch out to?

A

Branches to chest and abdomen (parasympathetic) and large sensory capacity from gut and lungs
Recurrent laryngeal not parasympathetic, runs back up to neck to supply skeletal muscles of larynx

42
Q

What do the sympathetic trunks do?

A

Receive branches from spinal nerves T1-L2, distribute sympathetic nerves to smooth muscle glands throughout the body, bring pain fibres back to CNS from viscera (referred pain)

43
Q

From which fibres of the sympathetic trunk do the splanchic nerves form?

A

T5-T12

44
Q

What is the thoracic duct?

A

Lymph duct returning lymph from lower limbs, pelvis, abdomen and left thoracic wall to blood

45
Q

Where is the thoracic duct located?

A

Begins below diaphragm at cisterna chyli, between oesophagus and aorta on RHS, crosses behing oesophagus to LHS between T7 and T4

46
Q

Where does the thoracic duct drain into?

A

Left brachiocephalic vein

Decks in LSS 1 - Thorax anatomy, Respiratory and Circulatory system Class (27):