VH Dissector: Mediastinum

In this exercise we will reverse dissect the structures related to the superior, anterior and posterior mediastinum by adding them into the VH Dissector one by one. Click on the step buttons to progress through the model build.

Begin with the thoracic cage

STEP 1

Add the thoracic duct.

Notice that the thoracic duct begins in the abdomen with the cisterna chyli (chyle is the name for the contents that flows through the lympahatic system). This duct empties into the left brachiocephalic vein.

STEP 2

Add the azygos vein

Zygos means two, therefore an Azygos vein means "not" two. You can see the remnants of the two veins with the hemizygous vein. The azygous vein empties into the superior vena cava.

STEP 3

Add the diaphragm

Notice that both the hemizygous veins and the thoracic duct leave the abdomen near the crus of the diaphragm that allows the aorta to pass from the thorax to the trunk. Rotate the cadaver to get a sense of this relationship.

STEP 4

Add the esophagus

STEP 5

Add the tracheo-bronchial tree

STEP 6

Add the major arteries of the thorax. Use the highlight tool to access labels identifying all the structures in your model.

STEP 7

Now return to the VH Dissector to continue building the mediastinum model:

Add the pulmonary arteries.

STEP 9

Add the major veins of the thorax.

Then, rotate the cadaver so that you can visualize the azygous vein draining directly into the superior vena cava just above the right bronchus.

STEP 10

Add the pulmonary veins.

STEP 11

Add the lungs.

STEP 12

Add the thymus which sits just posterior to the sternum.

STEP 13

The mediastinum separates the two pleural cavities which contain the lungs, and extends from the thoracic inlet to the diaphragm and from the sternum to the thoracic vertebrae.

In this view the the left side of the thorax has been removed in order to allow us to visualize the compartments of the mediastinum.

Using the Highlight tool to highlight thoracic vertebrae T4 and T5. Then draw a line between the sternal angle and the space between T4 and T5. Superior to this line is the superior mediastinum.
Visualize the anterior, middle and posterior compartments of the inferior mediastinum.

STEP 14

Add the right and left vagus nerves.

The right and left vagus nerves follow the esophagus through the superior and posterior mediastinum.

STEP 15

Add the ligamentum arteriosum which is the remnant of the ductus arteriosus.

STEP 16

Add the right and left recurrent layngeal nerves.

Note that the left recurrent laryngeal nerve wraps under the aorta very near to the ligamentum arteriosum.

The right recurrent laryngeal goes under the right subclavian artery.

STEP 17

Add the phrenic nerve which originates from the anterior rami of C3 to C5. It follows the scalene muscle of the neck and enters the thoracic inlet between the subclavian artery and vein.

The phrenic nerve is lateral to the vagus nerve. Trace its path from its entry into the superior mediastinum as it follows a path between the pleura and the pericardium to the inferior mediastinum and enters the diaphragm.

STEP 18

Add the mediastinal lymph nodes and discuss the drainage of these nodes and their implications in health and disease.

STEP 19

Additional Review Bookmarks

Below are some additional links to VH Dissector Bookmarks to help you preview and review the anatomy of the thorax:

Nerves of the thorax in relation to the bronchi and ribs: Highlights the pathways of the vagus and phrenic nerves (posterior and anterior to the hilum of the lung respectively) as well as the location of the intercostal nerves relative to the ribs.

Credits:

VH Dissector steps modified for Drexel Dissector by Dr. Haviva Goldman from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.

CT Scans from radiopaedia.org

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