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47 Cards in this Set

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Where is the mediastinum located?
In the thoracic cavity found between the two pleural cavities.
Borders of the Mediastinum
Superior- Superior Aperture of Thorax
Inferior- Diaphragm
Anterior- Sternum and the costal cartilages
Posterior- Thoracic vertebral bodies and intervertebral discs from T1-T12
Medial/Lateral- Mediastinal Pleura (between two pleural cavities)
3 Parts of the Inferior Mediastinum
1) Anterior - bordered anteriorly by sternum/transversus thoracic muscles/costal cartilages & posteriorly by anterior border of pericardial sac
2) Middle - unexplained
3) Posterior - unexplained
Superior mediastinum is separated from the Posterior mediastinum by what?
Imaginary line, drawn from the sternal angle directly posteriorly to the intervertebral disc between T4/5
Most anterior structure located in the superior mediastinum
Thymus
What is the thymus, and what are the differences in young/adult?
Primary lymphoid organ in the body that gradually becomes involuted as we become older. It's bilobed.
Blood and Venous supply of the Thymus
Blood - branches of the internal thoracic artery called anterior mediastinal branches and from anterior intercostals
Venous - Inferior thyroid vein off of the internal thoracic vein
What is a thymoma?
A cancer of the thymus that can become malignant in younger people (very rare)
What vessels are most anterior in the superior mediastinum?
Veins
What forms the right and left brachiocephalic vein?
Subclavian and internal jugular
Is the right or left brachiocephalic vein longer and why?
Left because it passes anteriorly to the vessels coming off of the arch of the aorta
What two things form the superior vena cava?
Right and Left brachiocephalic vein
What part of the superior vena cava is in the superior mediastinum, and which part is in the middle mediastinum?
Superior Mediastinum - Superior 1/2 of superior vena cava
Middle - Inferior 1/2 of superior vena cava
Where does the arch of the aorta (ascending aorta) turn into its arch?
Around the second costal sternal cartilage junction
General early path of the arch of the aorta and its clinical significance
As it ascends out of the heart, crosses over the left main bronchus, right at the bifurcation of the treaches. It's now anterior to esophagus. If arch has aneurism, will press on esophagus and bronchial tubes (mainly left main bronchus). (very common)
In which direction are aortic aneurisms mostly easily treated and why? How are they treated?
Posteriorly because it can be compressed on the posterior abdominal wall to slow bleeding. To treat, go in through femoral artery, put a sheath internally that blocks these off and platelets cannot adhere.
3 Branches off of the arch of aorta
Brachiocephalic trunk, left common carotid, and left subclavian
How does the phrenic nerve run in the superior mediastinum and what does it run with?
Descends down on the lateral aspect of the pericardial sac and runs with the pericardiacophrenic artery, a branch of the internal thoracic artery
Where does the arch of the azygous run?
Arches over the root of the lung, ending into the superior vena cava
Where does the left vagus nerve descend between on the superior area of the mediastinum?
Between the trachea and esophagus
Where does the right vagus nerve descend? What branch comes off of the right vagus nerve, and what's its course?
Descends across the arch of the aorta and then the recurrent left laryngeal artery, then hooks around underneath the ligamentum arteriosum
What is the ligamentum arteriosum and what did it used to do?
Remnant of the ductus arteriosus, which shunts blood from the pulmonary artery directly into the aorta so it doesn't have to circulate through the lungs.
Bronchial cancer/metastatic lung cancer that invades lymph nodes around trachea may invade which nerve and cause paralysis on the left side of trachea (causing hoarseness)
Left recurrent laryngeal nerve
How would a doctor check to see if someone had bronchial/metastatic lung cancer?
Look down into larynx and see which side is paralyzed. Look for obvious changes to the epithelium of the area.
What does the recurrent laryngeal innervate?
Passses up to innervate the larynx and gives motor innervation to the esophagus for voluntary movement
3 Parts of the Esophagus and their muscle composition
1) Superior 1/3 - voluntary (skeletal) muscle
2) Middle 1/3 - mixture of voluntary and involuntary (smooth) muscle
3) Distal 1/3 - Goes into stomach and passes through diaphragm (made up of involuntary smooth muscle)
Why do you have to be careful when you intubate someone?
Trachea is anterior to the esophagus, and cartilaginous rings are incomplete posteriorly, so you can easily poke through and pierce the esophagus
Where does the posterior mediastinum begin superiorly?
It begins below intervertebral discs T4/5
Give the relationship of the arch of the aorta to the esophagus as one goes from superior to inferior.
Superiorly, arch of aorta is anterior to the esophagus. As one goes inferiorly, esophagus becomes anterior to the aorta, particularly where it passes through the diaphragm and the esophageal hiatus.
What are the common things that can constrict the esophagus?
Pharynx, arch of the aorta, left main bronchus, trachea, or diaphragm
What is the most common place for an esophageal constriction?
Diaphragm
What causes the stomach to push back up through the diaphragm because the abdominal cavity is so large that they compress the diaphragm and up it goes?
Hiatal Hernia
What are the branches of the descending thoracic aorta?
(Visceral)
A Right Bronchial Artery
2 Left Bronchial Arteries
Pericardial Branches
Esophageal
Mediastinal

(Parietal)
Superior Phrenic branch
Subcostal branch
Intercostal Arteries
What do the left bronchial arteries supply?
Bronchi, trachea, tissues of lungs, lymphatics around the lungs, superior part of the esophagus
What does the superior phrenic branch of descending (thoracic) aorta supply?
Passes down to posterior aspect of diaphragm to help supply diaphragm with help of the musculophrenic artery
Which intercostal branch is the subcostal branch of descending aorta and which rib is it below?
12th intercostal branch and below 12th rib
What is the cisterna chylii? Where is it? What major channels pass into it?
Receives lymphatic drainage from the abdominal viscera and drains into the thoracic duct. Located below the diaphragm. One channel is from abdominal viscera. 2 paired channels come up from the lower extremities of pelvic region.
Give the course of the lymphatics beginning with the cisterna chylii and relation to aorta/esophagus.
Cisterna cylii goes through diaphragm along with the aorta
Begins to the right of the aorta and to the left of the esophagus. Around T4 to T6, crosses to left and descends deep to arch of aorta and esophagus, to reach thoracic duct.
How much of the body does the thoracic duct drain? What part of the body does it drain? What drains the rest of the body?
Drains 75% of the body; everything but the right arm, head, neck, and thorax. Right lymphatic duct drains the rest.
Where does the right lymphatic duct drain into?
It terminates/drains into the junction on the right between the right subclavian and internal jugular
What type of autonomic innervation do the superior and inferior 1/3 of esophagus have?
They both have sympathetic and parasympathetic innervation.
What does the left vagus nerve turn into as it comes down toward the diaphgram?
Anterior vagal trunk.
What vagus nerve principally makes up the anterior vagal trunk and which makes up the posterior vagal trunk?
Left vagus - anterior vagal trunk
Right vagus - posterior vagal trunk
On which side of the body do the splanchnic nerves reside?
Right side of the body
Give the spinal nerve innervation of the following splanchnics:
1) Greater
2) Lesser
3) Least
1) T5-T9
2) T10-T11
3) T12
Tell about the type of innervation of splanchnic nerves.
Pre-ganglionic sympathetic nerves, which have passed out with the root of the nerve through white rami and back down to form these nerves. They pass inferiorly into the abdominal cavity and terminate in some plexuses instead of innervating structures in the mediastinum or thoracic cavity.
Which ganglia do the greater, lesser, and least splanchnic nerves run to?
Greater/Lesser - Celiac ganglion
Least - Aorticorenal ganglion