. A treatise on anatomy, physiology and hygiene : designed for colleges, academies and families. the anterior side of the spinal column. 199. In the erect position, there is a constant slight oscil-lation of the body backward and forward, like the movementof a pendulum; while, in the stooping posture, the muscleson the posterior side of the spinal column are kept in a stateof continued tension and contraction, to prevent the body fromfallmg forward. This enfeebles the muscles of the back, andexhausts the nervous energy, while position favorstheir development and power, because there
. A treatise on anatomy, physiology and hygiene : designed for colleges, academies and families. the anterior side of the spinal column. 199. In the erect position, there is a constant slight oscil-lation of the body backward and forward, like the movementof a pendulum; while, in the stooping posture, the muscleson the posterior side of the spinal column are kept in a stateof continued tension and contraction, to prevent the body fromfallmg forward. This enfeebles the muscles of the back, andexhausts the nervous energy, while position favorstheir development and power, because there is an alternatecontraction and relaxation of the muscles. Again, in thestooping position, the lower limbs are curved at the knee. In 198. Why will a person who stands erect walk furtheri and perform morttabor, than if he assumed the stooping posture ? 199. Why aie the muMlesof the back so soon exhausted iu the stooping position ? HYGIENE OF THE MUSCLES. 97 this altitude, there is a constant tension of the muscles of thelower extremities, which produces muscular exhaustion. Fig. 48. Fig. tig. 48. 1, A p-erpendicular line from the centre of tlie feet to the upper extreinitvof the spinal column, where the head rests. 2, 2, 2, The spinal column, witli its threenatural curves. Here the head and body are balanced upon the spinal column andoints of the lower extremities, so that the muscles are not kept in a state of erect position of the body and head is always accompanied with straight lowerliml)s. Fig. 49. 1, A perpendicular line from the centre of the feet. 2, Represents theunnatural curved spinal column, and its relative position to the perpendicular, (1.)The lower limbs are curved at the knee, and the body is stooping forward. Whilflstanding in this position, the muscles of the lower limbs and back are in continuedtension, which exhausts and weakens them. What is represented by figs. 48 and 49 r 9 98 ANATOBIY, PnYSIOLOGY, AND HYGIENIi. 200. When it is necessary
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