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.

51. Outline briefly the anatomy of how sensory input gets into the spinal cord and how motor commands to skeletal muscles gets out.

Answer: Sensory information gets into the spinal cord from the skin and joints, etc, via mixed (motor and sensory) spinal nerves, from there to dorsal roots, and from dorsal roots into the substance of the spinal cord. Motor information is carried from the spinal cord out the ventral roots, and from the ventral roots into mixed (motor and sensory) spinal nerves for distribution to skeletal muscles.

52. In a supine posture, why does the abdominal wall come forward during relaxed inhalations?

Answer: The abdominal wall comes forward during supine inhalations for two reasons: first, because the abdominopelvic cavity is a closed cavity and something has to yield when the dome of the respiratory presses inferiorly against the liver, stomach and other abdominal organs; and second, in a supine posture the abdominal wall is ordinarily relaxed and therefore CAN easily yield and come forward.

53. What is the one word that best describes the shape and function of the pelvic diaphragm in the male and female? Explain how this is so.

Answer: The word is hammock, and just as a hammock supports someone in a gentle curve, the pelvic diaphragm supports the pelvic organs in standing and sitting postures. The only thing you would have to add to a real hammock to make the analogy complete would be apertures in its base for convenience of elimination.

54. Compare and contrast the essential features of the triangle and revolving triangle postures.

Answers: First for comparisons, both postures are standing bends that are executed with the thighs abducted and the feet directed toward the side of the bend. Second, for contrasts, the triangle is a side bend in which one tries to keep the pelvis facing the front as much as possible, whereas the revolving triangle swivels the pelvis, bends forward, and then twists the torso so the chest is facing the rear. Excepting the comparisons and their similarity of names, the classic revolving triangle is practically unrelated to the classic triangle.

55. Devise a series of prone backends that are safe for older beginning students without back problems and without structural impediments such as chronically bent-forward postures.

Answer: Start 1) with the simplest prone relaxed crocodile, continue 2) with placing the hands in front of the face and pushing up moderately with the hands, then 3) place the hands in the classic cobra position and lift up with the back muscles, keeping the lower extremities firm, next 4) experiment with breathing, noticing that inhalation lifts the upper half of the body and exhalation drops it down independently of the back muscles, and last 5) experiment with pushing up into the simplest upward-facing dog keeping the knees on the floor.

56. What anatomical features prevent beginning and even many intermediate students from folding their chests down fully against their thighs while their knees are extended in paschimottanasana?

Answer: The first line of resistance is usually the hamstrings, which run from the ischial tuberosities past the rear of the knee joint to the tibia and fibula. The adductor muscles that take origin from the base of the pelvis far to the rear also contribute to the resistance, although not nearly as much as when the thighs are abducted. Inflexibility for flexion in the lower back also commonly contributes to the inability to come all the way forward.

57. Why is breathing restricted in sitting half spinal twists?

Answer: Breathing in half spinal twists is restricted for two reasons. One, the twisted torso compresses all the abdominopelvic organs and makes it difficult to press the dome of the diaphragm down during inhalation and makes it difficult to use the abdominal muscles to aid exhalation. Two, the upraised thigh is pressed against the abdomen, contributing to the same effects.

58. Why are even slightly inverted postures so helpful in improving the strength and mobility of the respiratory diaphragm?

Answer: There are two reasons. First, the diaphragm comes under tension and operates not only to draw air into the lungs but to press the abdominal organs away from the head against the force of gravity. Second, the weight of the abdominal organs insures that inverted exhalations will be more complete, thus reducing the functional residual capacity and improving the mobility of the diaphragm.

59. What is the most essential single feature common to both the classic shoulderstand and the third stage (version) of the plow posture? Assume no props are being used.

Answer: In both postures (for intermediate and advanced students only) the chin is pressed firmly against the sternum, acting as a lever to create a gentle traction throughout the neck.

60. What are the anatomical advantages to using a short, tilted-forward bench for sitting meditation?

Answer: There is little or no stress or tension on the adductor muscles, and the lumbar lordosis is easily maintained in its pitched-forward position. Thus it is easier to sit upright in this posture than in any of the classic cross-legged meditative sitting postures, which place tension on the adductors and result in rounding of the lower back to the rear in all but the most flexible students.