De Troyer A, Farkas G A
Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota 55905.
J Appl Physiol (1985). 1989 Dec;67(6):2614-21. doi: 10.1152/jappl.1989.67.6.2614.
The shortening of the canine parasternal intercostals during inspiration may have a passive component, and we have previously speculated that this might result from the actions of the levator costae and external intercostals (J. Appl. Physiol. 66: 1421-1429, 1989). The present studies were designed, therefore, to evaluate the pattern of activation of these muscles in the dog and to define their action on the rib cage during breathing. The results indicate that 1) the levator costae and external intercostals in the cranial part of the rib cage are active during inspiration, both in the supine and in the prone posture; 2) the inspiratory activation of the two muscles is increased after bilateral phrenicotomy; 3) it is increased even more when the parasternal intercostals in the different interspaces are also denervated; and 4) when the levator costae and external intercostals are the only muscles active during inspiration, the ribs continue to move cranially, and the sternum, rather than moving caudally as it does in the intact animal, moves cranially as well. Therefore, we conclude that the levator costae and external intercostals in the dog have a true inspiratory function. When needed, they are capable of causing a significant expansion of the rib cage and the lung during breathing.
犬吸气时胸骨旁肋间肌的缩短可能有被动成分，我们之前推测这可能是肋提肌和肋间外肌作用的结果（《应用生理学杂志》66: 1421 - 1429, 1989）。因此，本研究旨在评估犬这些肌肉的激活模式，并确定它们在呼吸过程中对胸廓的作用。结果表明：1）胸廓上部的肋提肌和肋间外肌在吸气时均有活动，无论是仰卧位还是俯卧位；2）双侧膈神经切断术后，这两块肌肉的吸气激活增加；3）当不同肋间的胸骨旁肋间肌也去神经支配时，其激活增加得更多；4）当肋提肌和肋间外肌是吸气时唯一活动的肌肉时，肋骨继续向头侧移动，胸骨不像在完整动物中那样向尾侧移动，而是也向头侧移动。因此，我们得出结论，犬的肋提肌和肋间外肌具有真正的吸气功能。必要时，它们能够在呼吸过程中使胸廓和肺显著扩张。
