That’s a Fact (Length of Adult Bones) 198.8 16.94 12.40 104.1 6.69 11.10 32.1 19.88 The average femur (thigh bone) is about ____ inches. The average sternum (breastbone) is _____ inches. The ulna (or inner lower arm) is on average ____ inches long, whereas the radius (outer lower arm) is about ____ inches long. The shin bone is called the tibia. On average it is about ____ inches long. References available Answers: Femur (thigh bone) = 19.88 Sternum (chest) = 6.69 Ulna (inner lower arm) = 11.10 Radius (outer lower arm) = 10.40 Tibia (shin bone) = 16.94 in