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.

31. Why is rapid adaptation of receptors for touch and pressure so significant when one approaches and then quietly holds a posture?

Answer: In the beginning (coming into a posture) touch and pressure receptors send a constant barrage of signals into the brain and spinal cord, signals that encourage the practitioner either to come further into the posture or to back off, so this input is very useful at that stage. After a few seconds, as soon as one stops moving, touch and pressure receptors start adapting to the stimuli and stop sending signals back into the central nervous system, enabling the practitioner to focus the mind single-mindedly on alternative objects of concentration such as breathing patterns.

32. What muscles are involved (at the end of exhalation) in keeping the upper half of the body lifted in the cobra variation with tightly engaged lower extremities (fig. 2.10), and what muscle lifts the body higher during inhalation?

Answer: Strap muscles on the posterior aspect of the neck, deep back muscles of the spine, extensors of the arms and forearms, gluteal muscles of the hips, and calf muscles on the posterior aspect of the leg all keep the body lifted during the course of exhalation. The respiratory diaphragm is then responsible for lifting the body even higher during inhalation.

33. What architectural plan of the rectus abdominis muscles and their innervation by motor nerves enables one to practice agni sara as described in chapter 3?

Answer: The rectus abdominis muscles are segmented, as illustrated by the washboard appearance of those muscles in body builders with 10% or less body fat. The individual segments are separated by tendinous inscriptions of connective tissue, and the individual segments of the muscles are separately innervated by motor nerves. Since different segments of the spinal cord innervate different segments of the muscles, it becomes possible (with practice) for the practitioner to control them separately and to produce the characteristic rolling in of the muscles from the pubis to the sternum during exhalation and their release in the opposite direction during inhalation.

34. Why is breathing such an important issue in standing backbends?

Answer: The diaphragm presses down against the abdominal organs during inhalation, and since the abdominopelvic cavity is a closed cavity, this increases intra-abdominal pressure. The increased intra-abdominal pressure in turn protects the spine and keeps excess tension off the intervertebral disks during backbends. Therefore, for maximum security (keeping the airway open) it is better to pull to the rear while inhaling maximally. On the other hand, experts in backbending who are certain of themselves can come into a more pronounced backbend at the end of exhalation when the dome of the diaphragm is higher in the torso and not pressing down against the abdominal organs. Beginners can do that as well, but they should be careful since taking tension off the diaphragm during exhalation also leaves them more vulnerable.

35. Why are the locust postures generally more demanding than the cobra postures?

Answer: First, they are very unnatural. In ordinary life one would rarely if ever lie prone and lift the thighs with the knees extended. By contrast, lifting the upper half of the body from a prone position is much less alien, as when a baby lifts its head to look up and forward. (Also, recall how children and teens often watch television while lying prone on the floor with their chins propped up with their hands and forearms.) Second, and more specifically, extending the thighs to the rear from a prone position with the knees straight is mechanically difficult, and the poses place peculiar stresses on the lower back, stresses that can shock those who are doing them for the first time.

36. In ideal circumstances of strength and flexibility, what are the main joints in the body that are of primary interest in forward bending postures?

Answer: First and possibly most important are the hip joints, in which one would like to be permitted at least 90 degrees of flexion at the synovial junctions between the heads of the femurs and the acetabula of the pelvic bones. Second is the lumbar spine, in which a total of 60 degrees of flexion between T12 and the sacrum is desirable. Third are the sacroiliac joints, in which ideally 5-10 degrees of slippage between the extremes of full nutation and full counternutation is permitted.

37. Considering all the alternative classes of postures in which one can accomplish twisting (inverted, standing, sitting, and supine), what order might be suggested for beginners in going from safest to most demanding?

Answer: Supine is the most elementary since the hips do not have to be flexed and since the back is protected by physical contact with the floor. Standing is next because the hips are neither flexed or extended (unless one purposely does combinations), and because twisting in a standing posture is common in everyday life. Inverted is third because (quoting from the text) "the lower extremities are free to move around in space rather than remaining fixed in positions that are defined by the placement of the feet on the floor." Sitting twists are most demanding because they are not what one experiences in daily life and because they place unusual and peculiar stresses on the hip joints.

38. For someone of average height and good health who has had extensive experience in doing the headstand, what is the expected systolic/diastolic blood pressure in muscular arteries at the top of the head, at heart level, and in the ankles? First list the pressures standing up and then list pressures that would be expected in the headstand.

Answer: Standing, blood pressure is about 100/60 mm Hg at the top of the head, 120/80 at heart level, and 210/170 in the ankles. In the headstand, blood pressure will be expected to be about 150/110 mm Hg at the top of the head, 120/80 at heart level, and 40/0 in the ankles.

39. What warnings prior to using a 5-inch shoulder support for the first time (lifted shoulderstand) are appropriate for a student who is otherwise experienced in practicing the classic shoulderstand? And second, what warnings prior to trying the classic shoulderstand are appropriate for a student who has always used a substantial prop for the shoulders.

Answer: First, try a thin mat under your shoulders before using a thick support, and explore how it is more difficult to keep your balance with your shoulders propped than while doing the classic shoulderstand (that is, without a prop). Second, if your training in the past has always been using a prop, be careful about coming incautiously into the classic shoulderstand so as not to overly stretch (or even tear) the trapezius muscles and strap muscles of the posterior aspect of the neck, muscles which are not accustomed to the stress of the unpropped posture.

40. How would you make an older student who is stiff and whose neck and lower back are uncomfortable more at ease in the (supine) corpse pose?

Answer: Have such a student lie on a fairly soft surface and place substantial pillows under the head and knees, the head because this student is probably bent forward chronically and will be comfortable only with their head lifted markedly, and the knees because supporting the knees in a flexed position takes strain off the lower back.