Tuesday, December 14, 2021

Anatomy, Dissection, and the Chong Mai

I just finished leading two 5-day dissection classes for the University of Tampa Physician Assistant program. While I was teaching ‘standard’ Western anatomy and guiding the student teams through the full body dissection, the Chinese medical channel system was never too far from my mind. I did occasionally share some of this information to the PA students, but it is obviously not the anatomy that they are studying, and I was sparing with this information. Below is one aspect I shared, and something that I got an even better appreciation of: the anatomy associated with the chong mai, or penetrating vessel.

Inferior epigastric artery and vein connecting
into iliac artery and vein.
One of the tables (there were teams of 5 people working on each donor) produced a very similar view to this image on the left. This is created by slowly resecting the obliques, then cutting the rectus abdominis from the pubic bone and resecting it superior. Underneath the rectus abdominis are these vascular structures which are the epigastric artery and vein. There is some complicated anatomy associated with the fascial layers inferior to the umbilicus (look up the arcuate line if you want more information), but suffice it to say that these vascular structures run deep to the rectus abdominis, and that the fascial plane that they run in dives a bit deeper as these blood vessels connect with the iliac artery and vein.

Epigastric artery and vein running
deep to the rectus abdominis

This fascial plane is what I associate with the Spleen sinew channel; it is the fascial plane that runs deep to the rectus abdominis, connects with the anterior diaphragm and then follows the diaphragm around to the crura (attachments on the lumbar spine) of the diaphragm. However, this fascial plane also houses these epigastric arteries and veins. These vascular structures change names as they reach the thoracic cavity, becoming the internal thoracic artery and vein (also called the internal mammary artery and vein), and running along the deep surface of the sternum and anterior ribcage. During dissection, we cut a window through the sternum and ribcage to access the thoracic cavity; when we remove this window and look at the undersurface, these vascular structures are apparent.

Internal thoracic artery and vein
running just posterior to the
anterior ribcage

Traveling superior, these arteries and veins join with the subclavian artery and brachiocephalic vein. It is not necessary for this discussion to get too detailed about this anatomy, but there is a relationship between these vessels coming from the thoracic cavity and similar vessels in the neck which supply the neck and face.

Collectively, these vessels supply the skin, muscles, and bone on the anterior region of the body, umbilical region, diaphragm, pleura, pericardium, thymus, and important structures of the neck.

Finally, in the thoracic cavity, these blood vessels branch into the intercostal arteries and veins; they drain into the thoracic aorta and a venous structure called the azygos vein, all in the posterior portion of the thoracic cavity and consistent with the posterior branch of the chong mai. Clinically, these vessels act as a collateral circulation for blood movement from and to the heart. If there is obstruction in the aorta, blood will take this collateral circulation route. If the blood is abundant, these vessels can be filled, so they act as a bit of a reservoir.

Go back and review the chong mai with this anatomy in mind and you will see it in an entirely different light. These structures are in the myofascial plane of the Spleen sinew channel, regulated by a Spleen channel point, SP 4, and they clinically match the description and topography of the chong mai.

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