The importance of Thoracic Spine for back bending asanas

For the first practical lesson of my YTT journey, while I was doing the first round of Surya Namaskar A, Master Ram commented that my lumbar spine is very flexible which there are good and bad advantages for it. And then I found out that I have been engaging the wrong spine/back muscles for the asanas and especially in back bending asanas even though I have been practicing yoga on and off for a couple of years.

During Back bending asanas, I will be engaging my lumbar spine the most and not my thoracic spine. Sure, it always looks nice and flexible to have that arch looking there but then again, I have never liked back bending due to the amount of pressure I got to put and have on my lower back. And after coming out of the pose, my lower back will be feeling extremely aching. And even if I were to do the asanas that will help to relieve the aching, I will still be feeling a little aching. So little did I know I am actually weakening my lumbar spine every time I am compressing it and jamming it.
So below are some of the basic and easy asanas/exercises that will help you to stretch, open up and activate your thoracic spine before we get into the back bending asanas.
Baby Cobra
1. Lay down on your belly and feet flat on the ground
2. Inhale, place your palms (fingers facing forward) beside the side of your chest and elbows internally rotate towards your midline
3. Exhale, draw your shoulder blades, engage your core and rhomboids
4. Inhale, keep your shoulders away from your ears, extend your chest and head up while using light pressure push on your hands.
5. Stay here for a couple of breaths
6. Last inhale to extend up higher
6. Exhale, gently lower down and rest your chin or forehead back on the floor or mat
7. Repeat the same for a couple of rounds with the option of lifting the hands away from the floor as well
Sphinx Pose
1. Lay down on your belly and feet flat on the ground
2. Inhale, place your elbows and internally rotate towards your midline. Hands and fingers will automatically be facing forward.
3. Exhale, draw your shoulder blades, engage your core and rhomboids
4. Inhale, keep your shoulders away from your ears, extend your chest and head up while using light pressure push on your elbows.
5. Stay here for a couple of breaths
6. Last inhale to extend up higher
6. Exhale, gently lower down and rest your chin or forehead back on the floor or mat
7. Repeat the same for a couple of rounds with the option of lifting the hands away from the floor as well
Kneeling Thoracic Spine Twist
1. In a table top position, ensure that your wrists are in-line with your shoulders and knees are in-line with your hips
2. Inhale, Abduct your right hand out and laterally rotate your rotator calf up while engaging your rhomboids
3. Exhale, medially rotate your rotator calf down and adduct your right hand back to the center
4. Do this for a couple of times and repeat the same on the other side
Wall Slides
1. Lean your back against the wall with your feet a few inches away from wall
2. Slightly flex your knee and press your whole back against the wall. Make sure there is no arch or hole on the lower back and head is still relaxed
3. Inhale, flex your elbows and lean against the wall right, in-line with your shoulders
4. Exhale, slide your elbows down towards your midline
5. Inhale, slide your elbows halfway up but not into a straight hands
6. Ensure that you are always engaging your core and rhomboids
Cat Cow against the wall
1. Standing facing a wall, about one foot away and placed your palms on the wall around the same height as your chest
2. Exhale, walk backward, flex your hips and fold into a L shape. You may adjust the placement of your palms in order to be in-line with your shoulders and pelvis is in a neutral position
3. Inhale, extend your spine
4. Exhale, flex your spine
5. Do this for a couple of times