I want you to answer honestly right now, do these hands look like yours when you are in Downward Facing Dog? (see #1)
No? How about this? (see #2)
Now, why am I being so picky about your hands and fingers positioning?
Truth is, the grounding and positioning of your hands and fingers play a crucial role in stabilizing any asanas that require arm balances (e.g., downward facing dog, caturangas, upward facing dog, crow pose, handstand, etc). Think of your hands like your feet whenever you are in poses that require their support. Think of the strength your hands need to provide to allow you to "stand" on your hands.
Moreover, when you have your hands turned outwards in weight-bearing positions, this can cause stress in your poor wrist joints. Whenever a student comes up to me with wrist pain, I always take a look at their hands in downward facing dog and plank first. Most of the time, their wrist pains are caused by the unstable grounding of the inner palms and the lifting of the knuckles, as you saw above.
Let's look at the anatomical structure of the wrist:
Notice how the forearm bone, the ulna, attaches to the metacarpals (wrist bones), and how thin it compares to the mighty radius. Now, doesn't it make sense that you distribute more weight towards the inner forearm and the inner palms due to the sturdier structure of the radius? The fleshier part of the inner palms also provide more strength and stability.
Why is it so hard for beginners to grip firmly into the inner palms, in particular the thumb and index fingers? Here are some of my hypotheses and thoughts:
First of all, being a bi-ped (walking on two feet), it is not required for us to use our hands to grip firmly on walls, grounds, and trees. If you don't use it, you'd lose it. We are no longer used to engaging our entire hands and fingers for grip and support.
Secondly, a lot of yoga asanas require us to engage our bodies to our center core, to concentrate on muscles more towards the center lines of our bodies, the deeper layers of muscles that keep the body strong, supported, and supple. Most workouts and exercises nowadays concentrate on the exterior toning and bulking, rather than the interior. I see a lot of students try to muscle their ways through caturangas and upward-facing dogs with the strengths of their pecs, biceps, and triceps. Although these big muscles are indeed involved, they forget about the underlying, smaller but crucial muscles [continue here] When I feel my forearm muscles at work, I feel a subtle connection to my inner armpits and core.
So, how do proper hand and fingers positioning look like? I give several different cues in my classes: (1) Plant the knuckles of your thumb and index fingers into the mat. (2) Imagine the skin of your fingers have sticky qualities like octopus' tentacles and you're plastering your hands into your mat. (3) Spread your fingers as wide as you can, then ground them.
To simplify and concentrate only on the workings of your hands, practice first on your hands and knees before you attempt a downward facing dog, since the latter pose has a lot of other things going on in the asana as well.
Of course, everyone learns differently, so this one is for my visual leaners:
aving strong foundations in the hands translate to strong support in the core. I guarantee that once you master the art of hand stabilizing in downward facing dog, arm balancing asanas will become much more accessible. Think about it, how else do you expect the rest of your body to rely its weight on your hands and arms when they are shaky and ungrounded?
Last but not least, take your time as you explore the phenomenal dexterities and strengths of your fingers as you work through the grounding aspects of your hands. I sometimes see yoga asanas as a way for us to explore the individualities as well as the continuities of our body parts just as a baby explores his own feet, legs, hands, mouth, and nose for the first time.
Try this out and experience the revolutionary effects of grounding your hands and fingers!