Superior & Posterior Mediastinum Flashcards
Define mediastinum
mass of tissues & organs separating the 2 lungs
Where is the mediastinum located
Located between sternum in front & vertebral column behind
Located from thoracic inlet above to diaphragm below
What does the mediastinum contain within it?
Contains all structures in thorax, except the lungs!
What is within the 5 different boundaries of the mediastinum?
Anterior: sternum & costal cartilages
Posterior: thoracic vertebral bodies
Superior: thoracic inlet
Inferior: diaphragm
Lateral: pleura
What organs/vessels/nerves are within the middle of the mediastinum?
Heart
Pericardium
Great vessels
phrenic nerves
What organs/vessels/nerves are within the superior portion of the mediastinum?
Trachea
esophagus
Great vessels
Vagus nerves
Thoracic duct
Thymus
What organs/vessels/nerves are within the posterior portion of the mediastinum?
Esophagus, descending aorta, vagal trunks, azygos and hemiazygos nerves
What organs/vessels/nerves are within the anterior portion of the mediastinum?
Thymus and lymph nodes
The superior mediastinum contains what 7 things?
Aortic arch
Superior vena cava
Esophagus & trachea
Thoracic duct
Vagus & phrenic nerves
Thymus gland
Azygos vein
The aortic arch is a continuation of ___ as it leaves the heart
ascending aorta
___ is a remnant of ductus arteriorsis
Ligamentum arteriosum
What are the 3 branches of the aortic arch?
Brachiocephalic trunk
Left common carotid artery
Left subclavian artery
What does the brachiocephalic trunk subdivide into?
Right subclavian artery & right common carotide
What combines to form the superior vena cava?
R & L brachiocephalic vein
What are the brachiocephalic veins?
Internal thoracic, vertebral, inferior thyroid, highest intercostal vein
Deoxygenated or oxygenated blood goes into the superior vena cava
Deoxygenated
Where does the superior vena cava lie?
lies on R side of mediastinum anterolateral to trachea & posterolateral to ascending aorta
Esophagus location
runs posterior to trachea, anterior to bodies of vertebra, posterior to L principal bronchus
Trachea location
between aorta & esophagus
Thoracic duct originates in the ___ and ascends through ___ and terminates at ___
Originates in abdomen & starts above diaphragm in a structure called cysterna chyli
Ascends through both posterior & superior mediastinum
Terminates at L subclavian & internal jugular veins
Vagus & phrenic nerve location
Neck
The R & L vagus nerve branches to ___.
What does the R recurrent laryngeal nerve loop around & ascend into?
What does the L recurrent laryngeal nerve loop around & ascend into?
Branches to pulmonary, esophageal & cardiac plexuses
R recurrent laryngeal nerve - loops around subclavian artery & ascends into neck to innervate larynx
Left recurrent laryngeal nerve - loops around aortic arch & ascends into neck to innervate larynx
Phrenic nerves come off of what roots?
3, 4, 5
What’s significant about the thymus gland?
It shrinks after puberty
The posterior mediastinum contains the
Descending aorta
Azygos vein
Homizygos vein
Thoracic duct
Esophagus
Phrenic nerves
Vagus nerves
Splanchnic nerves
Where does the descending aorta begin, where’s its location?
Begins at lower border of T4 (at level of sternal angle)
Located posterior to diaphragm
What are the branches of the descending aorta?
Bronchial artery
Posterior intercostal artery
Subcostal artery
Esophageal artery
Phrenic (superior) artery
The azygos vein is formed by the junction of the. Where does it end?
- R subcostal & R ascending lumbar veins
- Ends in lower part of superior vena cava
The azygos vein receives tributaries from
R posterior intercostal vein
R superior costal V
The accessory homizygos vein is formed by the union of
3 or 4 posterior intercostal veins above T8
The homizygos vein is formed by the junction of ___. It ends around ___
L subcostal & L ascending lumbar veins
Ends around T8 by crossing to R & joining azygos vein
The homizygos vein receives tributaries from
L posterior intercostal veins below T8
Accessory hemiazygos vein
The upper 1/3 is ___ & lower 2/3 is ___ in the esophagus
Voluntary
Involuntary
Where does the esophagus lie? What does it have a close relationship with?
Lies posterior to trachea & aorta in superior mediastinum & a bit to R of midline
Has close relationship w/ vagus, cervical, & thoracic sympathetic trunk
The vagus nerves lie behind the
Principal bronchi
In the esophageal plexus, ___ lie in the upper 1/3 & ___ lie in the lower 2/3
Voluntary motor fibers
Autonomic fibers
What are the vagal trunks? What lies in the anterior & posterior portion?
R & L nerves come together
Anterior = primarily from L vagus
Posterior = primarily from R vagus
What are splanchnic nerves? Where are the greater, lesser, & lowest splanchnic located?
Preganglionic sympathetic fibers that pass through diaphragm to abdominal viscera
Greater = T5-T10
Lesser = T9-T11
Lowest = T12 or last
The sympathetic trunk is part of what nervous system?
Autonomic nervous system
In the splanchnic nerves, ganglia communicate w/ intercostal nerves via
rami communications (gray & white)
Trosier’s sign is accompanied by
weight loss & vomiting
