Reflections from Cadaver Lab: Week 2 Day 5

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

On the fifth day of lab, we have the donors turned back into a prone position to complete the dissection of the posterior portion of the body. This is actually the first half of the day. For the second half, students are able to finalize any project that they are working with and start exploration to study anything. This week involved exposing the cranial cavity and brain, cutting the vertebral arch to expose the spinal cord and cauda equina, exploring the ligaments of the hip and knee, and dissecting deep into the medial thigh to get to the very deepest layer here. Here are some reflections:

1. I am teaching, so am back and forth between tables constantly to help advise, help with the dissection, and help identify structures. In some ways this slows down for me during the second half of the day. My colleague that I teach with frequently opens the cranial cavity and highlights structures of the brain. As one would expect, this generates a lot of enthusiasm, and I am usually working to complete a project while he is doing this. This year, I reflected back the muscles of the hip down to the level of the ligaments. This provided a very nice model for these ligaments. I was also able to reflect back to the deepest layer of the groin and expose the obturator externus and also get a very good model of the obturator nerve which could then be followed from the abdominal cavity medial to the psoas and into the medial thigh. This nerve has something to do with the Kidney divergent channel. I feel this is the case because I think that the du mai has something to do with the nerves which exit from the lumbar plexus and wrap around the abdomen to innervate the lower portion of the abdominal muscles such as the internal and external obliques and the transverse abdominis. Specifically, the ilioinguinal, iliohypogastric and subcostal nerve follow the trajectory and describe function of this vessel. I wrote a post about this recently, and you can find this here.
   
   The Kidney divergent channel is said to intersect with the dai mai at L2, which is exactly what the obturator nerve does. This is why I feel it is part of the Kidney divergent channel, at least the lower half of this secondary channel.


2. The lumbar plexus is houses between the anterior and posterior layers of the psoas major. We discuss this on an online recorded class available here. I was able to reflect back this anterior layer of the psoas and reveal the lumbar plexus nerves. On this specimen, the psoas was different than I have seen. It had two main grouping of fascicles and almost looked like two separate muscles. This muscle has an interesting fascicle arrangement all of the time, but this was different. I had two distinct branches that then blended with the iliacus muscle. The best I could tell was that the anterior and posterior layer were more distinct from each other than usual, but I was not able to return and figure this out because I got called to other areas for assistance.


3. Being able to move and palpate a specimen while seeing the structures helps inform what you feel. For instance, mobilizing the hips with just the ligaments holding the hips helps you feel what just the ligaments feel like in this movement. Or doing a varus and valgus stress test with the ligaments exposed helps refine this test. And doing Lachman;s test while watching a torn ACL move gives so much information.

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