Thursday, December 8, 2022

Reflections from the Cadaver Lab: Week 2 Day 4

Reflecting on my fourth day of week two teaching the 2022 Cadaver Lab.

Each year I teach this cadaver lab, I plan on posting some reflections at the end of each day. I did pretty well this year, posting for days 1-4 of the first week. And then I got off track. This is for two reasons. 1) Dissection lab is very tiring both mentally, but also physically. One is standing the entire day and working over a table, accounting for the physical aspect, but it is also mentally tiring due to the sustained concentration. This is especially true when you are teaching. 2) There is really so much to highlight that at the end of the day it almost makes it too difficult to remember what I was planning to post when I get home. This is made worse by point number one.

Day 4 is the same as last week. It is the day that evisceration occurs and the organs are studied. It is not only this, however. The dissection continues into deeper layers of the anterior neck and extremities so that you can follow myoneurovascular structures from the neck and into both the thoracic cavity but also the upper extremities and you can follow myoneurovascular from the abdominal cavity into the lower extremities. Day 4 is really the culmination of the week up to this point.

Here are some reflections:

  1. There are many things I teach to acupuncturists regarding the channel sinews (jingjin) and their myofascial connections. Reflection of the biceps brachii is a great example of this. With the biceps reflected, you get a great view of the coracobrachialis and the brachialis. The brachialis has two myofascial connections. On the lateral side of the humerus, it has a clear myofascial connection to the deltoids, especially the anterior fibers. Following this path highlights the a deep branch of the Lung sinew channel. However, the brachialis also has a clear myofascial connection to the coracobrachialis which highlights the Pericardium sinew channel. This connection is great in anatomy texts, but much more obvious on a fresh tissue dissection when you can put tension into these myofascial planes. Visually it is apparent, but the tactile portion helps solidify the understanding when considering how injury can affect this plane.

  2. The IT band is really a fascinating structure when you do dissection. It is really almost abstract because, to view this structure, you have to remove the fascia lata (the deep fascia of the thigh) while retaining the IT band. This means you cut an artificial line on the anterior and posterior border and remove the fascia lata off up to this line you created. There is a guideline regarding where you make this line and that is the TFL muscle. The ITB does have some variability in tension from specimen to specimen, but nothing like what you feel when you palpate patient's lateral thighs. There is far more variation with patients. So, all of these tight IT bands really has more to do with the baseline tension in the TFL and/or the underlying vastus lateralis. I think the vastus lateralis is the more likely thing practitioners are palpating. When reflecting the IT band, you follow under the TFL to the ASIS to reflect both together. You have to find the fascial plane between the TFL and the underlying gluteus medius when doing this. It is hard to differentiate. Which is also the case when you palpate and needle these structures on patients. I think many times, clinicians are sensing the gluteus medius and advancing the needle to this muscle when they think they are treating the TFL.

  3. The plantar foot is organized in layers which can be followed in dissection. The superficial layer has the plantar fascia which has a very clear connection to the underlying flexor digitorum brevis, but it also has a clear connection to the adductor hallucis. This is the layer of the Kidney sinew channel. The next layer involves has the flexor digitorum longus, quadratus plantae, and lumbricals. This is the layer of the Liver sinew channel. The final layer includes the tibialis posterior, flexor hallucis and adductor hallucis. This is the layer of the Spleen sinew channel. These layers are well depicted in Netter and other anatomy atlases because the plantar foot is so clearly organized this way in dissection. The channels would follow would also be associated with this order.

  4. I saw a pretty odd anomaly of the psoas major. I will look a bit closer and try to describe tomorrow.

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