The muscle Christian is talking about is highlighted in blue, and the tendon sheath is the blue tube at the bottom. My read is that that sheath had moved to the side a bit, closer to the others?
Anatomy atlases like that often include the tendon of the muscle in the marked muscle, so I’m talking roughly about the end of the thing that’s marked in blue on the image. From the view of that image, the blue muscle is the thing that’s most left at that point. In my case, it was moved right from that and so that you would still see it when looking at the hand from that perspective instead it being hidden on the other side of the hand.
I took a screenshot from my anatomy atlas app, hopefully it’s a bit helpful. https://i.ibb.co/RpMfpJX/Screenshot-20210603-191621.png
The muscle Christian is talking about is highlighted in blue, and the tendon sheath is the blue tube at the bottom. My read is that that sheath had moved to the side a bit, closer to the others?
Anatomy atlases like that often include the tendon of the muscle in the marked muscle, so I’m talking roughly about the end of the thing that’s marked in blue on the image. From the view of that image, the blue muscle is the thing that’s most left at that point. In my case, it was moved right from that and so that you would still see it when looking at the hand from that perspective instead it being hidden on the other side of the hand.