Goldman M D, Loh L, Sears T A
J Physiol. 1985 May;362:189-204. doi: 10.1113/jphysiol.1985.sp015670.
The activation of the levator costae, a set of axial muscles inserted between each rib and the vertebra immediately rostral, has been studied electromyographically in a human subject, standing upright, with head erect ('neutral' posture). Caudal levator costae muscles (T9, and T10) are active during eupnoea. Periodic activity in phase with inspiration occurs in admixture with different levels of tonic activity that is strongly influenced by posture. Postural changes and various voluntary respiratory manoeuvres which should lengthen or shorten the levator costae muscles increase and decrease, respectively, their activity in the 'neutral' posture. The tonic activity was most readily enhanced by contralateral flexion of the spine, and this could bring to threshold phasic activity not otherwise present. Conversely, ipsilateral flexion could abolish both phasic and tonic components. Active expiratory efforts and static voluntary relaxation of the respiratory muscles could diminish or abolish levator costae activity. Paradoxically, chest-directed inspiratory efforts maintained at elevated lung volume with open glottis could also diminish or abolish levator costae activity. We attribute this to shortening of the levator costae muscles and unloading of their muscle spindles by the elevation of the ribs due to the action of the external intercostal and parasternal muscles. The results are discussed in relation to the mechanical coupling between the diaphragm and the lower rib cage; emphasis is given to the possible independent motions of the lower two or three ribs and the abductor action of their corresponding levator costae muscles, based on anatomico-physiological considerations.
肋提肌是一组附着于每根肋骨与紧邻的上位椎骨之间的轴性肌肉。研究人员在一名直立、头部挺直（“中立”姿势）的人体受试者身上，通过肌电图对肋提肌的激活情况进行了研究。在平静呼吸时，下位肋提肌（T9和T10）处于活跃状态。与吸气同步的周期性活动与不同水平的紧张性活动混合出现，且紧张性活动受姿势的影响很大。姿势改变以及各种应会使肋提肌伸长或缩短的自主呼吸动作，分别会增加或降低其在“中立”姿势下的活动。脊柱对侧屈曲最容易增强紧张性活动，这可能会使原本不存在的相位性活动达到阈值。相反，同侧屈曲可能会消除相位性和紧张性成分。主动呼气努力以及呼吸肌的静态自主放松可能会减弱或消除肋提肌的活动。矛盾的是，在声门开放的情况下，保持肺容积升高的向胸部的吸气努力也可能会减弱或消除肋提肌的活动。我们将此归因于由于肋间外肌和胸骨旁肌的作用，肋骨抬高导致肋提肌缩短及其肌梭卸载。结合膈肌与下胸廓之间的机械耦合对结果进行了讨论；基于解剖生理方面的考虑，重点探讨了下两到三根肋骨可能的独立运动及其相应肋提肌的外展作用。
