What is the X in X-mas?
smooth muscle n.
Muscle tissue that contracts without voluntary control, having fine myofibrils but lacking transverse striations and found in the walls of internal organs, blood vessels, and hair follicles.
muscle that shows no cross stripes under microscopic magnification. It consists of narrow spindle-shaped cells with a single, centrally located nucleus. Smooth muscle tissue, unlike striated muscle, contracts slowly and automatically. It constitutes much of the musculature of internal organs and the digestive system.