Posterior Mediastinum

Question 1

Boundaries of the Posterior Mediastinum

Answer 1

Superior: horizontal plane thru the sternal angle
Posterior: bodies of vertebrae T5-T12
Anterior: pericardium
Lateral: mediastinal pleurae (left and right)
Inferior: diaphragm

Question 2

Thoracic Aorta

Answer 2

To the left and slightly posterior to the esophagus

Question 3

Relationship between the heart to the esophagus

Answer 3

The esophagus lies immediately posterior to the left atrium and part of the left ventricle

Question 4

Right Vagus Nerve

Answer 4

It’s in the angle formed by the arch of the azygos vein and the superior vena cava
-the fibers of the right vagus nerve spread out on the (mostly) posterior surface of the esophagus

Question 5

Left Vagus Nerve

Answer 5

Crosses the left side of the arch of the aorta

-it’s fibrous contribute to the (mostly) anterior part of the esophageal plexus

Question 6

Esophageal Plexus

Answer 6

Near the diaphragm, fibers of the esophageal plexus come together to form the anterior and Posterior vagal Trunks

• the vagal trunks are found on the inferior part of the esophagus, just before they pass thru the diaphragm.
• the vagal trunks pass thru the diaphragm with the esophagus and innervate a large part of the GI tract

Question 7

Arch of the azygos vein

Answer 7

It arches superior to the root of the right lung

-it turns into the azygos vein which goes inferiorly to the level of the diaphragm

Question 8

Thoracic Duct

Answer 8

Lies immediately to the left of the azygos vein, posterior to the esophagus

• it’s thin walled and easily torn
• inferiorly it passes thru the diaphragm with the thoracic aorta
• superiorly the termination of the thoracic duct is the junction of the left internal jugular vein and the left subclavian vein

Question 9

Posterior intercostal veins

Answer 9

Tributaries to the azygos vein (on the right side)

-on the left side: they drain into the hemiazygos vein or accessory hemiazygos vein
These veins then cross the bodies of the ninth and eight thoracic vertebrae respectively and terminate by draining into the azygos vein

Question 10

Posterior Intercostal Arteries

Answer 10

The right arteries cross the midline on the anterior surface of the vertebral bodies

Question 11

Sympathetic Trunk

Answer 11

It crosses the head of ribs 2-9.
Inferior to rib 9, it lies on the sides of the thoracic vertebral bodies

-it has one sympathetic ganglion for each thoracic vertebral level

Question 12

Rami Communicantes

Answer 12

(White and gray) connect each intercostal Nerve with it’s corresponding thoracic Sympathetic ganglion
(The more lateral of the 2 rami is the white ramus communicantes)

Question 13

Greater Splanchnic Nerve

Answer 13

Receives contributions from the fifth thru the ninth thoracic sympathetic ganglia and that it’s not completely formed until lower thoracic levels
-its found on the sides of vertebral bodies T5-T9 while the sympathetic trunk crosses the heads of the ribs 5 to 9 (the trunk is located posterior to the greater splanchnic nerve)

Question 14

Lesser Splanchnic Nerve

Answer 14

Arises from the 10th and 11th thoracic sympathetic ganglia

Question 15

Least Splanchnic Nerve

Answer 15

Arises from the 12th thoracic sympathetic ganglion