Thoracic cavity 2 Flashcards
What important structures are found at the level of T4 in the superior mediastinum?
Superior vena cava
Arch of the Aorta
What structures are found posterior to the manubrium?
✓ 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
What are the structures found in the posterior mediastinum?
✓Vertebral bodies ✓Proximal (posterior) costal segments ✓Proximal segments of posterior intercostal vessels ✓Proximal segments of intercostal nerves ✓Sympathic chain with its ganglia
Describe the location of the thoracic aorta
✓ 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
What are the two types of branches from the thoracic aorta?
Visceral branches
Parietal branches
What are the visceral branches of the thoracic aorta?
✓ Oesophageal arteries ✓ Bronchial arteries → usually 2 on the left + 1 on the right ✓ Pericardial branches ✓ Mediastinal branches ✓ Superior phrenic artery (curious emoji)
What is the purpose of the oesophagus?
Transport of food and fluid to stomach
Describe the path of the oesophagus until where it enters the thorax
✓ 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
Describe the histological structure of the oesophagus
✓ 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
Describe the path of the oesophagus once in the thoracic cavity
✓ In the lower posterior mediastinum, it swings forwards and to the left
✓ Pierces the diaphragm at the level of T10
Where can constrictions be found on the oesophagus?
− Upper oesophageal sphincter
− Arch of aorta
− Left main bronchus
− Diaphragm (esophagael hiatus)
why is it important to know where the constrictions of the oesophagus are?
Constrictions ... • are more likely to cause blockage • hinder passage of instruments • slow down the passage of caustic substances → more damage
Describe the venous drainage of the oesophagus
✓ 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
What occurs to the oesophagus in some alcoholics?
Cirrhotic liver disease→ portal hypertension → oesophageal varices
What is the nerve supply of the oesophagus?
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
Where are the superior and inferior tracheobronchial nodes found and where do they drain?
✓ Clustered around the trachea and oesophagus
✓ Receives the lymph from the lung→spread of lung tumour
What lymph nodes are present in the mediastinum?
Superior and inferior tracheobronchial nodes
anterior mediastinal nodes
posterior mediastinal nodes
Where are the anterior mediastinal nodes found?
Around the brachiocephalic veins
Where are the posterior mediastinal nodes found?
Behind the heart and adjacent to the oesophagus
Name all the thoracic lymph nodes (haha fuck u bro)
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
Why is it important to know where the lymph nodes are?
Certain lymph nodes are potentially amenable to sampling by EBUS, TBNA, or EBUSTBNA
Describe the path of lymph drainage in the thorax?
Alright so basically
Watch the lecture
Where do the lymph trunks drain back into the venous return in the left side of the thorax?
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
Where do the lymph trunks drain back into the venous return in the right side of the thorax?
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
Describe the function of the thoracic duct
Carries the lymph from much of the body (except thorax, upper limb and head and neck of the right side)
Chylothorax occurs here
Describe the path of the thoracic duct
✓ 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)
