Mediastinum Flashcards
Where does the superior mediastinum terminate
Superior thoracic aperture
What are the boundaries of the superior mediastinum
Superior-Thoracic inlet Inferior-Level of sternal angle (T4/5) Anterior-Manubrium of sternum Posterior-Vertebral bodies of T1-4 Lateral-Pleura of lungs
Contents of the superior mediastinum (vessels)
ABC'S --> Arch of the Aorta Brachioceophalic aa left Common Carotid aa left Subclavian aa
- -> Superior vena cava;
- Brachiocephalic vv
- Left superior intercostal vv
- Supreme intercostal vv
- Azygous vv
Where does bifurcation of brachiocephalic aa
Sternoclavicular joint
Where do the SVC and IJV join and what do they become
Sternoclavicular joint
-Join to become brachiocephalic vein
What nerves are in the superior mediastinum
Left vagus nerve Left recurrent laryngeal nerve Right vagus nerve Phrenic nerve Sympathetic trunk
What is the course of the left vagus nerve
Enters the superior mediastinum between the left common carotid and left subclavian
-Descends anteriorly to the aortic arch, before travelling posterior to the left bronchus
What is the course of the right vagus nerve
Runs parallel to the trachea and passes posteriorly to the superior vena cava and the right primary bronchus
What branch does the right vagus nerve give off
Right recurrent laryngeal nerve
What does the right recurrent laryngeal nerve loop around
Right subclavian artery
What branch does the left vagus nerve give off
Left recurrent laryngeal nerve
What does the left recurrent laryngeal hook around
Aortic arch
What does the vagus nerve innervate
Parasympathetic innervation to viscera via pulmonary, cardiac and oesophageal plexuses
What do the recurrent laryngeal nerves innervate
The muscles of the larynx
What Is the course of the phrenic nerve
Superficial of anterior scalene Lateral to vagus then great vessels Passes anterior to hilum of lungs Right leaves via canal opening od diaphragm at T8 Left pierces diaphragm at heart apex
Where is pain referred to for phrenic nerve
Shoulder/upper arm
What is the thymus the site of
T cell maturation
What muscles are found in the superior mediastinum
sternohyoid and sternothydoid
Where is the anterior mediastinum
Between sternum and pericardium
What are the contents of the anterior mediastinum
Loose connective tissue Fibrous bands Fat Lymphatic vessels Lymph nodes Internal thoracic vessel branches THYMUS in children
contents of the middle mediastinum
Pericardium Heart Ascending aorta Pulmonary trunk SVC Arch of azygos vein Main bronchi Cardiac plexus Phrenic nerves
Contents of posterior mediastinum
thoracic aorta Thoracic duct Azygos + hemiazygos veins Oesophagus Oesophageal plexus Thoracic sympathetic trunks Thoracic splanchnic nerves Posterior mediastinal lymph nodes
What does the azygos system drain
- Back
- thoracic-abdominal column
- Mediastinal viscera
Where is the hemiazygos vein
Left side of column posterior to aorta as far as T9
Where is the accessory hemiazygos vein
Left side of column T5-T8
->Crosses over T7-T8 vertebrae
What does the thoracic duct drain
All body except upper right quadrant
Where does the thoracic duct start and where does it enter
Cisterna Chyli (L1-L2)
–>Enters junction of IJV and left SCV (left venous angle)
What does the sympathetic chain provide
Sympathetic innervation to structures
Where is the sympathetic chain in the superior thorax
Against heads of ribs
Where is the sympathetic chain in the middle of the thorax
Costovertebral joints
Where is the sympathetic chain in the inferior thorax
Sides of vertebral bodies
What are the 3 splanchnic nerves and their root values
Greater- T5-T9/10
Lesser-T10-T11
Least-T12
Where are presynaptic fibres found
5-12
Where does metastasis occur through in a carcinoma of a breast
Normally via lymph, but can also go via azygos/hemiazygos
What is a potential pathway for a breast carcinoma to spread and why
breast- vertebrae - brain and cranium
-Because the lymph vessels, azygos and hemiazygos system run alongside vertebrae and communicate with internal vertebral venous plexuses
