Mediastinum Flashcards
(43 cards)
What are the boundaries of the mediastinum?
Superior: Thoracic inlet Inferior: Diaphragm Lateral: L. and R. pleural cavities Anterior: Sternum and CCs Posterior: T1 - T12
Primary divisions of the mediastinum and their borders:
- Superior mediastinum
(Separated by the transverse thoracic plane = T4/T5 to Sternal Angle) - Inferior mediastinum
a. Anterior (anterior to pericardial sac, posterior to body of sternum)
b. Middle (bounded by pericardial sac)
c. Posterior (anterior to T5 - T12), posterior to pericardial sac and diaphragm)
What connects the neck and the chest?
Superior mediastinum
What are the contents of the superior mediastinum?
- Thymus
- Great vessels (Brachiocephalic veins, SVC, aortic arch, brachiocephalic trunk, left common carotid artery, left subclavian artery, vagus nerve, phrenic nerve, cardiac plexus of nerves
- Trachea, Esophagus, left recurrent laryngeal nerve
- Thoracic duct and lymphatic trunks
- Level VII group of lymph nodes
- Parathyroid (ectopic)
Anterior to Posterior:
Thymus -> Veins -> Arteries -> Airway -> Alimentary Tract -> Lymphatic Trunks
From which pharyngeal arches did the parathyroid and thymus come from?
3rd and 4th Pharyngeal arch
Primary lymphoid organ located in the inferior part of the neck and anterior part of the mediastinum where T-lymphocytes mature.
Thymus
What is the blood supply of the thymus?
Anterior intercostal and anterior mediastinal branches of internal thoracic arteries
Enlarged thymus leading to obliteration of superior and anterior mediastinum. Motor issue wherein eyelids are nonfunctional in the afternoon.
Myasthenia gravis
Returns blood from all structures superior to the diaphragm except lungs and heart
Superior Vena Cava
Formed by the union of the internal jugular veins and subclavian veins at the level of the _____________.
Ends and enters right atrium at level of the ____________.
1st right costal cartilage
3rd right costal cartilage
Squeezing of the SVC due to a tumor causing an enlarged head and prominent veins in neck
SVC Syndrome
Remnant of the fetal ductus arteriosus
Ligamentum arteriosum
What lies above the plane of the sternal angle of Louis (2nd rib)?
Arch of the aorta
Where does the arch of aorta become the thoracic aorta?
After it passes the 2nd left rib
First and largest branch of the arch of aorta:
Brachiocephalic trunk
Brachiocephalic trunk divides into:
- Right common carotid artery
- Right subclavian artery
What arches around the right main bronchus?
Azygos vein
Phrenic nerve arises from:
C3, C4, and C5 of the cervical plexus
Phrenic nerve motor and sensory supply:
Motor: Diaphragm Sensory: - 1/3 of diaphragm (superior and inferior) - Pericardium - Mediastinal pleura
Extent of Trachea
C6 - T4 (Sternal Angle) then it bifurcates into right and left bronchi
Entrance of esophagus to diaphragm
Esophageal hiatus
Constrictions of the esophagus
15 - 23 - 40 cm from upper incisors
Where does the thoracic duct drain into?
Junction between IJV and subclavian vein
Anterior mediastinum boundaries
Superior: Superior mediastinum / sternal angle
Inferior: Diaphragm
Anterior: Body of sternum and transversus thorasis muscle
Posterior: Pericardium
