Mediastinum Week 8 FINISHED Flashcards
What does mediastinum mean in latin?
Middle septum
What covers the mediastinum?
Mediastinal pleura
What does the mediastinum contains?
All the thoracic visceral and other structures
Does the mediastinum contain the lungs?
NO, it is found BETWEEN the lungs
What are the boundaries of the mediastinum?
Superior: superior thoracic aperture/outlet
Inferior: diaphragm
Anterior: Sternum and costal cartilages
Posterior: Thoracic vertebrae
What does the mediastinum contain?
The heart and great vessels Oesophagus Trachea and its bifucations Thymus gland Thoracic duct Lymph nodes Phrenic nerve and vagus nerves
Is the mediastinum a mobile or immobile region?
Very mobile
What movements has to be accommodated for inside the mediastinum and what structures accommodate for this movement?
Movement, volume and pressure changes have to be accommodated for in the mediastinum (e.g. tracheobronchial tree movement with respiration, pulsating of blood vessels etc).
Connective tissue, mediastinal pleura and elasticity of the lungs accommodates for this.
What are the boundaries of the superior mediastinum? What is the shape of the superior mediastinum?
The boundaries are:
The superior thoracic apertures to the plane running between the sternal angle anteriorly to T4/5 IVD posteriorly (transverse thoracic plane). Anteriorly is the manubrium, and posteriorly is the thoracic spine T1-T4
The superior mediastinum is wedge shaped.
What are 2 other names for the sternal angle?
Angle of louis
Manubriosternal joint.
What 3 things happen at the level of the transverse thoracic plane?
The trachea bifurcates
The location of the concavity of the aortic arch
Just superior to the bifurcation of the pulmonary trunk
What are the boundaries of the inferior mediastinum?
The boundaries:
The transverse thoracic place to the diaphragm.
What is the inferior mediastinum further broken up into?
Anterior, middle and posterior parts
Where does the anterior mediastinum lie? What does it contain?
It is a potential space, it lies between the pericardium and the sternum and contains:
- the thymus gland
- sternopericardial ligaments
- lymph nodes
- branches of the internal thoracic vessels.
What is in the middle mediastinum?
The heart and adjoining great vessels
Adjoining lung roots
Phrenic nerves
Where is the posterior mediastinum found?
It is the region posterior to the heart and the pericardium.
Its boundaries are:
Posteriorly - T5-T12
Anteriorly - Domed regions of the diaphragm
What is found within the posterior mediastinum?
The oesophagus The thoracic aorta The azygous, hemiazygous and accessory hemiazygous veins The thoracic duct Lymph nodes
Where is the thymus located? Between what vertebral levels does it extend?
Located in the lower neck and anterior part of the superior mediastinum as well as the anterior mediastinum.
It can extends between the level of the 4th costal cartilage to the lower poles of the thyroid gland
How many lobes does the thymus have? What are they enclosed by?
2 lobes, one right and one left. The right lobe usually overlaps the left.
It is enclosed by a capsule
Thymus dimensions
5cm long, 4cm wide 6cm thick
Who is the thymus most prominent in?
Children. After puberty it decreases in size
What is anterior to the thymus gland?
Sternohyoid and sternothyroid muscles, the manubrium and the upper aspect of the body of the sternum with adjacent costal cartilages
What is posterior to the thymus?
The pericardium, arch of the aorta, left brachiocephalic vein and trachea.
What is the arterial supply of the thymus?
Inferior thyroid and internal thoracic arteries (major branch of the subclavian artery)
What is the nerve supply for the thymus?
Vagus
Upper sympathetics
What is the function of the thymus?
Central gland in the lymphatic system, which secretes hormone Thymosin.
It is involved in the maturation and development of the immune system
T-cells develop in the thymus before migrating to the spleen and lymph nodes
