With the first ribs fixed by neck muscles (scalene muscles and sternocleidomastoid muscle), the intercostals muscles (especially external intercostal muscles and interchondral part of internal intercostal muscles of opposite side), elevate the 2nd to 12th ribs and thus act as inspiratory muscles.
Medical Dictionary. arrhythmia. play. noun arÂ·rhythÂ·mia \Ä-Ërith-mÄ-É\. Medical Definition of arrhythmia. : an alteration in rhythm of the heartbeat either in time or force.
siÂ·nus arÂ·rhythÂ·miÂ·a. rhythmic, repetitive irregularity of the heartbeat, the heart being under the control of its normal pacemaker, the sinuatrial node. Synonym(s): juvenile arrhythmia. sinus arrhythmia. an irregular cardiac rhythm in which the heart rate usually increases during inspiration and decreases during expiration. It is common in children and young adults and has no clinical significance except in elderly patients.