Surgery General a149f973 Scabbard Trachea; True is? A Flattening of trachea B Caused by lateral compression by swellings C Caused by lateral compression by tumors D All of the above High-Yield Explanation SCABBARD (SABER-SHEATH) TRACHEA Flattening of trachea caused by lateral compression by swellings or tumors. Causes: Carcinoma thyroid, thyroiditis, carcinoma larynx, goitre.