Interval 4 Flashcards
Parts of the mediastinum:
- superior (above sternal angle)
- anterior
- inferior
- posterior
superior mediastinum:
- between 1st vertebrate and first rib
- horizontal plane between sternal angle and the intervertebral disc (T4 - 5)
- trachea, brachiocephalic vein, thymus, aortic arch, esophagus, thoracic duct
posterior mediastinum contents:
- esophagus with vagus nerve
- descending aorta
- thoracic duct
- sympathetic trunk
- inferior to horizontal T4-5 plane
- between the pericardium, vertebral column, and diaphragm
middle mediastinum contents:
- heart
- ascending aorta
- pulmonary trunk
- pulmonary veins
- phrenic nerves
anterior mediastinum:
- smaller vessels and nerves
- fat
CT
-thymus in children
Layers of the superior mediastinum:
- endocrine layer: thymus (extends into anterior)
- venous layer: SVC, left/right brachiocephalic veins
- arterial layer: arch of aorta & 3 branches: brachiocephalic artery, left common carotid, and left subclavian
- respiratory layer: trachea, arch of aorta, azygos vein
- digestive layer: contains esophagus
brachiocephalic veins:
- posterior to the sternoclavicular joint
- form by the union of the internal jugular vein and a subclavin vein
- left brachiocephalic vein crosses behind thymus
division of the brachiocephalic artery:
- right common carotid and right subclavian
* common carotids in the middle
ligamentum arteriosum:
- fetal remnant of ductus arteriosus (shunted blood from PT directly to aorta)
- between left pulmonary artery and arch of aorta
Presence of trachea in cross sectional imaging means what?
–you are in the neck or superior mediastinum
indentations on the esophagus:
- two: one from the arch of the aorta (on the left) and one from the left main bronchus anteriorly
- causes constriction site
- two other constriction sites: origin of the esophagus in the neck and at the esophageal hiatus of the diaphragm
thoracic duct:
- contains lymph from the entire abdominal region
- courses posterior to the esophagus
- deviates left, empties into the left subclavian and left internal jugular veins
Vagus Nerve:
- left and right
- through superior mediastinum to the posterior and pass posterior to the root of the lung
- form esophageal plexus on esophagus
- cardiac and pulmonary branches enter the cardiac plexus
left recurrent laryngeal nerve:
- in superior mediastinum
- comes off the vagus nerve after it passes the arch of the aorta
right recurrent laryngeal nerve:
- NOT in superior mediastinum
- hooks around the right subclavian
phrenic nerves:
-pass anterior to the root of the lung
Where to hear mitral valve?
- most commonly diseased
- 5th intercostal space, few cm from the sternum
- problems cause enlarged left ventricle and hypertrophy of right
pulmonary hypertension:
- mitral valve problem (mitral stenosis) causes left ventricle to swell and blood get backed up in left atrium/lungs
- right ventricle hypertrophies as it tries to compensate to the increased resistance
Thrombus in left atrium:
- due to back up from mitral stenosus
- blood clot, can travel into left ventricle -> circulation -> brain -> stroke
posterior mediastinum
- inferior to horizontal T4-5 plane
- between the pericardium, vertebral column, and diaphragm
esophagus muscle:
- skeletal muscle in upper 1/3
- smooth muscle in lower 1/3
- mix in the middle
esophagus innervation:
-esophageal plexus (formed by left/right vagus)
hemiazygos veins:
- drain into the azygos after crossing midline at T8 (azygos drains into SVC at sternal angle)
- receive blood from posterior intercostal veins
organs of the posterior abdominal wall:
kidneys, ureters and adrenal glands