There are approximately 642 skeletal muscles within the typical human it only takes seven of these to twist the throttle on your crotch rocket it probably takes considerably more to hang on for dear lifet shirt design reads it takes 37 muscles to frown 17 to smile 7 to twist the throttleour crew neck short sleeved mens t shirts are 100 premium cotton in a soft pre shrunk jersey knit our womens t shirts are lighter weight 150g tees made with deluxe 30s soft style yarns for a soft feel