help 44- during respiration a- inspiration is a passive movement with no aid from muscles y b- external intercostals muscle is an inspiratory muscle & (c) during inspiration the diaphragm is pulled down d- forced expiration is aided by relaxation of the abdominal muscles x49- the coronary arteries arise from the arch of aorta x b-) each gives atrial and ventricular branches c- doesn't supply the conducting system x d- anastomose with each other at anterior surface of the heart.