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.
Figure 100 â ECG demonstrating premature atrial contractions. Discussion. A cardiac arrhythmia or dysrhythmia is an abnormality in the cardiac muscle contraction or variation in the normal rhythm. This includes rhythm loss, irregular rhythms or abnormal regular rhythms.