FORCES DEFORMING THE RIB CAGE.
Interim rept., Feb-Jun 66,
MILAN UNIV (ITALY) ISTITUTO DI FISIOLOGIA UMANA
Pagination or Media Count:
The relaxed rib cage was squeezed along the lateral diameter at different lung volumes with closed airways. The force applied, the decrease of the lateral diameter, the increase of the dorsoventral diameter, and the esophageal and gastric pressures were measured. During a 10-kg. squeeze the increase of the esophageal pressure is negligible, notwithstanding the decrease of the rib-cage cross section and the lack of muscle contraction. The diaphragm is lowered, probably through the lowering of the ribs. A marked decrease of the rib-cage size without a parallel change of the esophageal pressure occurs also when shifting from sitting to standing at functional residual capacity. The work done by the equipment to reduce the lateral diameter as much as during expiratory efforts is about one-third the compressive work done by the muscles during maximum static efforts performed at functional residual capacity and at 60 of the vital capacity. During the breathing cycle the deformation work may become appreciable when the flow resistances are high. Author
- Anatomy and Physiology