Thoracic Cavity 2 Flashcards
What are the boundaries of the anterior mediastinum?
- sternal body and xiphisternum
- pericardium
- lungs and pleura
What is contained within the anterior mediastinum?
- Thymus
- Internal mammary vessels
- Lymoh Nodes (Terrible)
- Connective Tissue
- Fat-cell tissue
- Lower pole of thyroid (rare)
- Ectopic parathyroid
What is the thymus?
Bi-lobed organ of lymphoid tissue
Where is the thymus located?
Between the manubrium, sternum and pericardium
Where does the thymus extend from?
from the lower neck (jugular notch) to 4th costal cartilage (sometimes below aortic arch)
Describe the progression of the thymus with age
Active in early childhood until puberty with increasing fibro-fatty infiltration with age
How many planes are in the superior mediastinum?
3
What are the 3 planes of the superior mediastinum?
- Venous Plane
- Arterial Plane
- Visceral Plane (oesphagus and trachea)
Where do the phrenic and vagus nerves lie?
between the planes of the superior mediatsinum
Where is the venous plane located?
Anterior and lateral
What are the brachiocephalic veins formed by?
Internal jugular and subclavian veins
Where does the left BCV pass?
anterior to the arch of aorta; posterior to the manubrium
What is the SVC formed by?
right and left brachiocephalic veins
Where does the arch of the azygos join?
Superior Vena Cava
Where does the SVC enter?
Right atrium
Where is the ascending aorta located?
in the middle mediastinum
What does the ascending aorta continue as above the sternal angle?
Arch of aorta
How does the aortic arch curve?
up, backwards and slightly left behind the lower half of the manubrium
Where does the thoracic aorta continue?
in the posterior mediastinum
What are the 3 branches of the aorta from right to left?
- Brachiocephalic trunk - divides into right subclavian and right common carotid
- Left common carotid artery
- Left subclavian artery (posterior and to the left of the trachea)
Where does the pulmonary trunk lie and what is its relationship to the aorta
within the pericardium, to the left of the ascending aorta
What does the pulmonary trunk divide into at T4/5?
(inferior to the aortic arch)
Right and left pulmonary arterys
- Right = posterior to ascending aorta and superior vena cava
- Left = inferior to arch of aorta and anterior to the thoracic aorta
What occurs posterior to the sternoclavicular joint?
- formation of the brachiocephalic veins by the internal jugular and subclavian veins.
- Division of the brachiocephalic trunk into its branches on the right side
What occurs posterior to the 1st right CC?
formation of superior vena cava by right and left brachiocephalic veins
What occurs posterior to the 2nd right CC?
arch of the azygos vein joins the superior vena cava
What occurs posterior to the 3rd right CC?
Superior vena cava enter the RA
Where is the posterior mediastinum?
Between heart, pericardium, diaphragm and vertebrae
What does the posterior mediastinum contain?
- Vertebral bodies
- Proximal costal segments
- Proximal segements of intercostal vessels and nerves
- Sympathetic chain with its ganglia (posterior wall)
What is the thoracic aorta and where is it situated?
Continuation of the aorta arch and situated between the level of the sternal angle and aortic hiatus (T12)
Where does the thoracic aorta lie?
Lies on the left of the thoracic vertebral bodies but moves to midline in lower thorax
Name the visceral branches of the thoracic aorta
- Visceral Branches:
- Oesophageal arteries
- Bronchia arteries
- Pericardial branches
- Mediastinal branches
- Superior phrenic artery
What is the trachea?
Air-transport tube in the midline of the neck
Where is the trachea located?
Starts at the level of C6 vertebra and ends at trahceal bifurcation (carina)
What movement can occur with the trachea?
May rise and descend to the level of T4 and T6 during deep inspiration and expriation
What is the function of the oesophagus?
Transport of fluid and food from oral cavity
Where is oesophagus located?
Starts in the midline as a continuation of the pharnyx at C6, inferior to the border of the cricoid cartilage and it descends between the trachea and vertebral column. It enters the thorax behind the trachea, with the arch of aorta to its left in the superior mediastinum
Describe the muscle found in the 3 sections of the oesophagus
Upper = striated muscle (swallowing = voluntary and rapid)
Middle = mixed striated and smooth
Lower = smooth muscle
Epithelium of the oesphagus
Stratified squamous epithelium
What does the oesophagus do in the lower posterior mediastinum?
swings forward and to the left
Where does the oesophagus pierce the diaphragm?
T10 = oesophageal hiatus
Give the 4 constrictions of the oesophagus
- Upper oesophageal sphincter
- Arch of aorta
- Left main bronchus
- Diaphragm
What is the clinical significance of a constriction?
More likely to cause blockage
Name the mediastinal lymph nodes
Superior and inferior tracheobronchial nodes
Where are the mediastinal lymph nodes found? And where do they receive lymph from?
- Clustered around the trachea and oesphagus
- Recieves lymph from the lung
Describe the order of lymph drainage from the lungs
Describe the lymph drainage into the thoracic duct and give where this drains into
Describe the lymph drainage into the right lymphatic duct and where this drains into
Function of the thoracic duct
Carries lymph from much of the body (except thorax, upper limbs, head and neck of the RHS)
Where does the thoracic duct begin?
Cisterna chyli
Carries all lymoh gtom abdomen and lower limbs
Where does the thoracic duct lie?
Lies between the aorta and azygos vein in the posterior mediastinum
Describe the path of the thoracic duct
- Crosses at T4/5 behind the oesphagus to ascend on its left side
- Arches over the apex of the left lung anf pleura
- Opens in the left brachiocephalic vein at the junction of the left internal jugular and left subclavian vein (Pirogoff’s angle)
