Thoracic cavity 2

Question 1

What important structures are found at the level of T4 in the superior mediastinum?

Answer 1

Superior vena cava

Arch of the Aorta

Question 2

What structures are found posterior to the manubrium?

Answer 2

✓ Posterior to the sternoclavicular joint: Formation of the brachiocephalic veins (BCV) by the Internal jugular (IJV) and subclavian (ScV) veins; division of Brachiocephalic trunk to its branches on the right side
✓ Posterior to 1st right CC: Formation of superior vena cava (SVC) by right and left BCVs
✓ Posterior to 2nd right CC: Arch of the azygos vein joins SVC
✓ Posterior to 3rd right CC: SVC enters the right atrium

Question 3

What are the structures found in the posterior mediastinum?

Answer 3

✓Vertebral bodies 
✓Proximal (posterior)
costal segments
✓Proximal segments of posterior intercostal vessels
✓Proximal segments of intercostal nerves
✓Sympathic chain with its ganglia

Question 4

Describe the location of the thoracic aorta

Answer 4

✓ Distal continuation of the aortic arch
✓ Between the level of sternal angle and aortic hiatus (T12)
✓ Lies on the left of the thoracic vertebral bodies, but moves to midline in lower thorax

Question 5

What are the two types of branches from the thoracic aorta?

Answer 5

Visceral branches

Parietal branches

Question 6

What are the visceral branches of the thoracic aorta?

Answer 6

✓ Oesophageal arteries
✓ Bronchial arteries → usually 2 on the
left + 1 on the right
✓ Pericardial branches
✓ Mediastinal branches
✓ Superior phrenic artery (curious emoji)

Question 7

What is the purpose of the oesophagus?

Answer 7

Transport of food and fluid to stomach

Question 8

Describe the path of the oesophagus until where it enters the thorax

Answer 8

✓ Starts in the midline as the continuation of the pharynx at C6, inferior border of cricoid cartilage
✓ It descends between the trachea and the vertebral column
✓ Enters the thorax behind trachea, with the arch of the aorta to its left in the superior mediastinum

Question 9

Describe the histological structure of the oesophagus

Answer 9

✓ Upper 1/3: striated muscle as swallowing is voluntary and rapid
✓ Middle 1/3: mixed striated + smooth
✓ Lower 1/3: smooth muscle
✓ Stratified squamous epithelium

Question 10

Describe the path of the oesophagus once in the thoracic cavity

Answer 10

✓ In the lower posterior mediastinum, it swings forwards and to the left
✓ Pierces the diaphragm at the level of T10

Question 11

Where can constrictions be found on the oesophagus?

Answer 11

− Upper oesophageal sphincter
− Arch of aorta
− Left main bronchus
− Diaphragm (esophagael hiatus)

Question 12

why is it important to know where the constrictions of the oesophagus are?

Answer 12

Constrictions ...
• are more likely to cause blockage
• hinder passage of instruments
• slow down the passage of caustic substances → more
damage

Question 13

Describe the venous drainage of the oesophagus

Answer 13

✓ Veins of upper and middle thirds drain to azygos, hemiazygos, accessory hemiazygos (systemic) and lower third to the left gastric vein (portal system)
✓ There are anastomoses between the veins of middle and lower thirds.
− Porto-systemic or portocaval anastomosis

Question 14

What occurs to the oesophagus in some alcoholics?

Answer 14

Cirrhotic liver disease→ portal hypertension → oesophageal varices

Question 15

What is the nerve supply of the oesophagus?

Answer 15

Thoracic part
✓Left vagus→Anterior vagal trunk
✓Right vagus→Posterior vagal trunk
✓ Fibres from the anterior and posterior vagal trunks, together with sympathetic fibres form the oesophageal plexus around the oesophagus

Question 16

Where are the superior and inferior tracheobronchial nodes found and where do they drain?

Answer 16

✓ Clustered around the trachea and oesophagus

✓ Receives the lymph from the lung→spread of lung tumour

Question 17

What lymph nodes are present in the mediastinum?

Answer 17

Superior and inferior tracheobronchial nodes

anterior mediastinal nodes

posterior mediastinal nodes

Question 18

Where are the anterior mediastinal nodes found?

Answer 18

Around the brachiocephalic veins

Question 19

Where are the posterior mediastinal nodes found?

Answer 19

Behind the heart and adjacent to the oesophagus

Question 20

Name all the thoracic lymph nodes (haha fuck u bro)

Answer 20

Low cervical, supraclavicular and sternal notch nodes

Upper paratracheal (right and left)

Lower paratrachael (right and left)

Subaortic

Subcarinal

Paraesophogael (below carina)

Pulmonary ligament

Hilar

Interlobar

Lobar

Question 21

Why is it important to know where the lymph nodes are?

Answer 21

Certain lymph nodes are potentially amenable to sampling by EBUS, TBNA, or EBUSTBNA

Question 22

Describe the path of lymph drainage in the thorax?

Answer 22

Alright so basically

Watch the lecture

Question 23

Where do the lymph trunks drain back into the venous return in the left side of the thorax?

Answer 23

Left Jugular Lymph Trunk (Left side of head & Neck), Left Subclavian Lymph Trunk (Left upper limb) and Left Bronchomediastinal Trunk (Left Thorax)

All drain to the thoracic duct, then to the left brachiocephalic vein

Question 24

Where do the lymph trunks drain back into the venous return in the right side of the thorax?

Answer 24

Right Jugular Lymph Trunk (Right side of head & Neck), Right Subclavian Lymph Trunk (Right upper limb) and Right Bronchomediastinal Trunk (Right thorax)

All drain to the right lymphatic dict, then to the right brachiocephalic vein

Question 25

Describe the function of the thoracic duct

Answer 25

Carries the lymph from much of the body (except thorax, upper limb and head and neck of the right side)

Chylothorax occurs here

Question 26

Describe the path of the thoracic duct

Answer 26

✓ It starts at the cisterna chyli
✓ Lies between the aorta and azygos
vein in the posterior mediastinum
− Pulsation of the Aorta promotes lymph flow
✓ At T4/5 crosses behind the oesophagus to ascend on its left side
✓ Arches over the apex of the left lung and pleura
✓ Opens into the left brachiocephalic vein at the junction of the left internal jugular and the left subclavian vein (Pirogoff’s angle)