Mediastinum Flashcards
where is sympathetic chain wrt vertebral column?
lateral to vertebral column
which side of the mediastinum is the SVC on?
superior vena cava is on right side
Describe the course of the esophagus
- originates at C6
- pass from neck to superior mediastinum
- posterior to trachea
- into inferior (posterior) medastintum
- through diaphragm at T10
- ends at T11
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descibe borders of anterior mediastinum
continuous with superior mediastinum at sternal angle, bottom is diaphragm, anterior is sternum and posterior is pericardium
boundaries of superior mediastinum
from plane through jugular notch and T1 vertebra down to
plane though sternal angle and T4/T5 intervertebral disc
where does thoracic aorta begin/end?
- begins at T4/T5 IV disc
- ends at T12 vertebral level at aortic hiatus (to become abdominal aorta)
contents of anterior mediastinum
- thymus (extends into anterior mediastinum)
- loose CT and fat
- lymph vessels and lymph nodes
- mediastinal branches of internal thoracic vessels
where is thymus
root of neck (superior mediastinum and anterior mediastinum)
immediately deep to manubrium
Superior vena cava returns blood from what structures to heart?
returns blood from everything superior to diaphragm except heart and lungs
contents of middle mediastinum (13)
- heart
- ascending aorta
- inferior portion of SVC
- terminal portion of azygous vein
- primary bronchi
- pulmonary trunk
- R and L pulmonary arteries
- pulmonary veins
- phrenic nerves
- pericardiacophrenic vessels
- cardiac plexus
- IVC
- lymph nodes
what is azygos sytem of veins?
- longitudinal veins that receive blood from the body wall and mediastinal viscera
- forms collateral pathways between IVC and SVC
thoracic duct drains lymph from where?
from all of body except right upper quadrant
When the aortic arch is ascending where is it in relation to other structures?
aortic arch ascends anterior to right pulmonary artery and trachea, then goes posterior
Trachea and esophagus orginate at what vertebral level?
C6
describe path of hemiazygos & accessory hemiazygous veins
normally empty into azygous vein but path is variable
What occurs at the indicated spots?
Label A-D
A. Sympathetic chain
B. Greater splanchnic nerve
C. Lesser splanchnic nerve
D. Least splanchnic nerve
branches of aortic arch
- brachiocephalic trunk (1st branch)
- right common corotid artery
- right subclavian artery
- left common carotid artery (2nd brach)
- left subclavian artery (3rd branch)
describe path of azygos veins
- originates around L1
- enters thorax @ posterior mediastinum via aortic hiatus
- ascends to the right of thoracic duct
- arches over root of right lung to join SVC
at what level does the superior vena cava pass into the mediastinum and where does it terminate?
into mediastinum at sternal angle and terminates at level of 3rd costal cartilage
inferior mediastinum boundaries
from plane through sternal angle and T4/T5 intervertebral disc down to
diaphragm
further subdivided into anterior, middle, posterior mediastunum
describe path of left recurrent laryngeal nerve
- arises from left vagus nerve
- passes around aortic arch before ascending between trachea and esophagus to reach larynx
significant branches of thoracic aorta (6)
- posterior intercostal arteries
- esophageal arteries
- bronchial arteries
- mediastinal branches
- pericardial branches
- superior phrenic arteries
describe path of thoracic duct
- starts at cisterna chyli (~T12)
- ascends through posterior mediastinum posterior to esophagus between descending thoracic aorta and azygous vein
- goes left and enters superior mediastinum
- ends at junction of left subclavian vein and left IJV (internal jugular vein)
describe path of right vagus nerve
- enters superior mediastinum posterior to brachiocephalic vein
- descends posterior to superior vena cava and along right margin of trachea
- passes posterior to root of lung in posterior mediastinum
- branches into pulmonary plexus and inferiorly to esophageal plexus and posterior vagal trunk
which 3 thoracic splanchnic nerves course in posterior mediastinum and where are they formed?
- Greater splanchnic nerve (formed from T5-T9)
- Lesser splanchnic nerve (formed from T10-T11)
- Least Splanchnic nerve (formed from T12)
Whats the smallest subdivision of the mediastinum?
anterior (inferior) mediastinum
where is thoracic aorta wrt esophagus?
thoracic aorta is mostly to the LEFT of the esophagus
what are the great veins and what part of the mediastinum are they in?
- right and left brachiocephalic veins
- superior vena cava
all in superior mediastinum
Describe left vagus nerve path
- enters superior mediastinum posterior to left brachiocephalic vein
- passes anterior to aortic arch and posterior to root of lung in posterior mediastinum
- gives off left recurrent laryngial nerve
- branches into pulmonary plexus, inferiorly to esophageal plexus and anterior vagal trunk
what joins to form left and right brachiocephalic veins and where do they join?
union of internal jugular veins and subclavian veins
occurs posterior to sternoclavicular joint
what nerve supplys motor innervation to diaphragm?
phrenic nerve
what are the great arteries and what section of the mediastinum are they part of?
- arch of aorta (and proximal portion of its major branches)
- brachiocephalic trunk
- left common carotid
- left subclavian
all in superior mediastinum
what is the aortic arch continuous with on both sides?
continuous with ascending aorta
then continuous with descending thoracic aorta (posterior to root of left lung)
what is the primary lymphoid organ?
thymus
what unites to form superior vena cava and where does this occur?
left and right brachiocephalic veins join at level of 1st costal cartilage
phrenic nerve supplies sensory branches to what?
pericardium, mediastinal pleura, diaphragm
describe path of pericardiacophrenic vessels
- travel with phrenic nerves
- 3 structures
- pass anterior to root of lung and descend through the middle mediastinum between fibrous pericardium and medastinal pleura
describe path of phrenic nerve
- originates in neck (C3,4,5)
- pass anterior to subclavian artery and posterior to subclavian vein
- enter superior mediastinum
where does trachea end
ends at sternal angle (before inferior mediastinum)
where does arch of aorta start?
begins at level of sternal angle, posterior to 2nd right sternocostal joint (not covered by pericardium)
