Brad's Iyengar Yoga Notebook
Urdhva Mukha Svanasana
Urdhva Mukha Svanasana is done more commonly than Bhujangasana (Cobra) in the Iyengar school of yoga.   It is a more active asana than Bhujangasana.   The difference between Urdhva Mukha Svanasana and Bhujangasana is that in Bhujangasana you are trying to achieve more of a coiling of your spine, a back bending.   To this end, you do not straighten your arms in Bhujangasana but rather keep them bent and pull them with your hands on the mat (rather than pressing your hands into the floor as in Urdhva Mukha Svanasana) to draw your torso more and more into a coiling backbend.   Urdhva Mukha Svanasana involves pushing with your arms into the floor, straightening them, and focusing more on an extension of your spine than strictly a deeper coiling backbend like Bhujangasana.
When coming into the pose from a prone position, either place your hands on your mat far down your torso close to your floating ribs to begin with or you will need to drag your body forward so that your hips come closer to your hands as you raise your torso upward.   You can also come into the pose from Adho Mukha Svanasana by rolling over the tops of your toes.
As far as your feet are concerned, you may do the pose while remaining on the balls of your feet, or you may roll over the tips of your toes and be on the dorsum (tops) of your feet, which is the more classical variation.   Doing the pose on the balls of your feet is more work for your legs (your thighs in particular) and less work on your lower back.   Having your toes turned under gives you more access to the strength of your legs and doesn't compress your lumbar region as much.   This version on the balls of your feet is good for warming up your spine during the initial few Surya Namaskars, for example.   It is also good in general to stop at this point (on the balls of the feet) for people with low back problems.   Doing the pose in the classical way on the dorsum (tops) of the feet involves more work in the lumbar spine.
Actions of the hands, arms, and shoulders
Lengthen and broaden your hands on the floor as in Adho Mukha Svanasana.   Try to keep the pressure out of your wrists by shifting your weight a little more into the base joints of your fingers, especially your forefingers.   If you have a wrist injury, it helps a little to turn your hands outward in this and other poses.
Your shoulders should be aligned vertically over your hands with your arms perpendicular to the floor.   Lift up through your inner arms and turn your arms outward so that your inner elbow creases face forward.   Continue rotating your upper arms strongly outward throughout the pose.   Your arms should always be externally rotating in this pose, although it is difficult in this position, to create space for your chest to move through and past your arms.   Don't press your inner arms against your side ribs as you draw your chest forward and your elbows toward your buttocks.
The most critical part of this pose is the lift of your inner arms and how that action helps you to lift your chest.   These actions can be learned more clearly by doing the pose with your hands on blocks.   If your arms donít do their job 100%, weight and pressure falls into your lower back.   So address the lift of your inner arms over and over.   The lift of your inner, upper arms gives the whole action of the pose.
Draw your shoulder blades deeply into and down your back toward your hips and draw your shoulders down away from your ears.   Pull your shoulders back as much as possible.   Your shoulders must stay back as you take your chest through your arms by dragging your feet forward.   A good time to try to aim for in this pose is 3 minutes, though that is hard.   Geeta Iyengar says it sometimes takes her 60 seconds to set her shoulder blades properly in this pose.   Move your shoulder blades downward and into your back strongly.   Take your trapezius skin and the skin over your shoulder blades down your back.   Remember, it is the lower scapulae that you want to draw inward and lift from.
A more subtle shoulder action you should learn is to raise the middle part of your shoulders and lower the outer (heads) of your shoulders to lengthen your neck fully.
Actions of the torso, hips, and pelvis
Your chest should be out in front of your hands in this asana (unlike in Bhujangasana).   The feeling in your torso should be one of moving forward and upward to avoid compressing your lumbar area.   Circularize your armpit chest as in Tadasana.   There is a circular action that you should imagine in your shoulder blades moving down as your chest lifts upward.   Keep uplifting from your sternum toward the ceiling.   Broaden your chest from side to side.   Broaden and lift your collarbones.   Open your clavicles to the sides.
Move your side ribs forward more and more.   Lift the sides of your chest.   How much can you lift and expand (from side to side) you lower ribs?
Move your navel away from the floor and inward toward your spine and lift your pubic bone toward your navel.   Tuck your tailbone underneath and draw your pubic bone and abdomen upward toward your chest to help protect your lumbar spine.   This action is important in all backbends.   Move your tailbone toward your pubic bone and lift the front of your spine maximally.   Feel as if you are lifting your pubic bone toward your sternum.   Don't push your groins forward -- you have to lift out of your legs so you don't compress your lumbar spine.
Look upward without compressing the back of your neck.   Raising your chin up helps to move your thoracic spine in.   Hold your head back by lengthening your neck, not merely by tilting your head back.   The energy of this pose is one of a circle or smooth arc, not a bend at the low back.   This feeling also can be learned more easily by placing your hands on blocks.
Actions of the legs and feet
Have your feet hip width apart.   As in all backbends, firming your legs as much as possible will help make your spine more supple.   Lift the backs of your legs strongly toward the ceiling while at the same time elongating through both legs.   Draw your outer shins inward toward each other.   Tighten your buttocks and draw the backs of your thighs strongly toward your buttocks.   The feeling in your legs should be that of uplifting, as if you were supporting someone who is standing on your sacrum.   Try to feel that you are bending more from your upper and middle back than from your lower back.
The knees and thighs have a tendency to roll outward in all backbends with the tightening of the buttocks and tucking of the pelvis.   Roll the tops of your thighs and knees inward to counteract this tendency.   Lift your inner knees toward the ceiling.   Verify the front sides of your thighs are parallel to the floor.   Lift your inner thighs and spread your buttocks apart.   When you're up in the pose release your buttocks but continue to lift your inner thighs, inwardly rotating your upper legs.   Another way of saying this is to take the backs of your thighs outward away from each other.   This is the same action.   Also, hit your inner thighs outward toward your outer thighs.
You will need to do these leg actions before bringing your pelvis forward as previously discussed.
Don't lose your Virasana feet.   Make sure you are squarely on the centers of the top of each foot.   Do not allow them to turn inward (sickle).
(1) Press your hands to lift your chest.
(2) Press your feet down and lift your inner thighs.
(3) Lift your inner, upper arms, and
(4) Take your pelvis forward and upward.
Fully extend through your arms and legs as much as possible in this pose.
To come out of the asana, first roll back over your toes and press up into Adho Mukha Svanasana.   When moving into Adho Mukha Svanasana from Urdhva Mukha Svanasana, try to maintain the backbending flavor in your spine.