Note: For each of the following questions (one for each chapter in Anatomy of Hatha Yoga), please answer in 100 or fewer words using complete sentences.

11. In a lunging posture, what is the role of the quadriceps femoris muscle, and what is the technical term for describing its gross mode of operation as its muscle fibers become more active during the course of lengthening while coming into the lunge?

Answer: The quadriceps femoris muscles act as antigravity muscles in any lunging posture. They play a central role in maintaining your upright posture, especially on the side with the bent knee. The muscles lengthen eccentrically as you slowly drop your weight.

12. What is the significance of minute as compared to alveolar ventilation in yoga postures?

Answer: Minute ventilation is the total amount of air you breathe in and out over a period of 60 seconds (the touch of the breath in the nostrils, as yoga teachers like to say), and alveolar ventilation is the amount of air that gets beyond the anatomic dead space per minute (beyond the airways) and that is available for exchange with the blood. Alveolar ventilation is more important when we look at breathing exercises.

13. Why and how should novices be cautioned to stabilize the lumbar region while doing double leglifts?

Answer: Beginners should be encouraged to keep their lumbar region stabilized (either rounded to the rear in the fire exercise supported by the forearms, or pulled flat against the floor with the abdominal muscles for a standard supine double leglift), because during the course of any style of double leglift the psoas muscles pull forward strongly on the lower back, and such exercises place too much stress on the lumbar region unless it is held firmly in place.

14. Why is gravity the most fundamental issue regarding standing forward bends, especially for novices, and why is this the case? Finally, what are the two main possibilities regarding how standing forward bends are supported?

Answer: The role of gravity is the foremost issue in standing forward bends because the upper body is pitched so far off axis. Novices can either support such postures with external props such as the upper extremities, wall, desk, or block of wood, or they can support the poses internally with a combination of the skeleton, abdominal muscles, and respiratory and pelvic diaphragms.

15. Anatomically, what stops us from bending backward very far at the hip joints, and what is the significance of this anatomical design (same feature) for forward bending at the hips?

Answer: There is a spiral of ligaments (the pubofemoral ligament, the ischiofemoral ligament, and the iliofemoral ligament) that collectively becomes taut as we try to hyperextend the hip joints in a backward bend. As the spiral becomes tighter, extension becomes ever more insistently limited, and the head of the femur is driven ever more firmly against the hip socket (the acetabulum). Flexion, on the other hand, loosens the spiral, and this is what allows us to bend forward with comparative ease at the hips.

16. Under what circumstances and why is bending forward from the waist reasonable, and under what circumstances and why is bending forward from the hips desirable?

Answer: Bending forward from the waist (spinal flexion) is better suited for most stereotyped forward bending movements because there is less weight to contend with than in the case of bending forward from the hips and because the spine is a flexible rod well suited for bending and twisting. Bending forward from the hips is more desirable for most forward bending postures in hatha yoga because the hip joint is a synovial joint whose femoral head can rotate easily in the acetabulum.

17. Anatomically, what limits spinal twisting in the lumbar region?

Answer: Spinal twisting in the lumbar region is limited by the sagittal (front-to-back and up-and-down) orientation of the superior and inferior articulating processes of the lumbar spine, and by the fact that the axis of rotation is located well behind the lumbar intervertebral disks and vertebral bodies.

18. What are some of the more prominent differences between how a beginner and an advanced practitioner handle their body weight while coming into the headstand?

Answer: Beginners tend to support an excess amount of their weight on their arms and forearms, they are tempted to toss their feet up in the air and hope for the best, and they exhibit an uncertain balance from start to finish. Advanced students support more of their weight on their head and neck, they come up and back down gracefully and systematically, and they are confident of balancing their weight at all times.

19. What are the most important cautions for safely learning the classic shoulderstand?

Answer: Work first and with a lot of patience doing preliminary postures such as the various inverted action poses and quarter plow while always being careful not to force the head and neck into uncomfortable degrees of flexion and traction. Slowly increase your capacity over a period of weeks for straightening the body into the full posture. Many teachers teach students to prop the shoulderstand and plow with a thick pad or rolled-up blanket under the shoulders.

20. What are the boundaries of the four triangles with respect to the right tetrahedron that is formed by the classic meditative sitting postures?

Answer: One triangle lays on the floor below the base of the spine and the distal ends of the knees, with an imaginary line connecting the knees. Two more triangles are described by the upright spine behind, the right and left thighs, and the right and left upper extremities. The last triangle that completes the tetrahedron is described by imaginary lines running from the top of the head to the knees and connecting the knees.