In both Agnisambhasana (Firelog pose, or Ankle-to-Knee pose) and Gomuhkasana (Cow-Faced pose), one of the key anatomical factors is that the thighs need to laterally/externally rotate in order to keep the knees safe. If the thighs don't laterally rotate enough in these postures then the medial condyle of the femur will dig into the medial meniscus of the knee and overstretch the lateral collateral ligament (for a more detailed overview of this, be sure to check out the video Keeping the Front Knee Safe in Pigeon). A great hands-on assist in both postures is to manually press the outer thighs down to help facilitate the lateral rotation. For more flexible people, you can also deepen the stretch in these postures by adding a little bit of your body weight to the top of their pelvis to increase anterior tilt. Check out the video to see these assists, and then practice them with a friend or in class!
Are you practicing Virabhadrasana 2 with your hips "square to the side" and your front hip bone lifted in an effort to "make your pelvis more level"? These two cues seem to be very popular in Warrior 2, and while they might have some benefit early on, as your flexibility increases there is a good chance that they will lead to bony compression in your hip joints, which over time might wear down the cartilage and other soft tissues in and around the hip. This isn't going to benefit you in any way, and could potentially lead to osteoarthritis later in life, so it's good to learn how to recognize compression when it's happening so that you can back off. And if you're teaching asana, it's good to know how to cue the posture to help your students avoid compression.
While I probably shouldn’t have favorites, I do confess to having a special fondness for the piriformis. It’s got a super cool name that just kind of rolls off the tongue (click here to hear it pronounced), it feels great to stretch it, and when it’s flexible it’ll add much more sukha to your Sukhasana (Comfortable pose) and make postures like Eka Pada Galavasana (Flying Crow) more accessible. However, if it’s tight it will limit the ability of the femur to laterally rotate within the hip joint, which has a lot of potentially not-so-great consequences (both on and off the yoga mat). By taking the time to learn more about this little muscle you’ll be able to more skillfully stretch it in your own practice and help your students find ways to safely stretch it in theirs.
Check out this fun little video that I put together awhile ago showing a posture progression that prepares for Eka Pada Galavasana, Flying Crow. I’ve updated this post to include some bullet points after the video indicating which muscles need to be stretched, and which postures you can stretch them in.
When coming into pigeon pose, if a student is unable to laterally rotate the thigh at the hip joint sufficiently they may inadvertently overstretch the ligament on the outside of their knee (the LCL) and/or compress the soft tissue on the inside of the knee (the medial meniscus). In the video below we explore how this might happen, and offer a few suggestions that can remedy the issue.