Femur is a bone of human body which is also known as thigh bone. This is the biggest bone of the body and is found in the upper thigh. Femur is the strongest bone in human body that can help in bearing stress. This bone gets broken when the pressure goes up to 18,000 pounds or above per square inch. The upper end of femur is called head that has ball-like shape. It is connected with acetabulum which is like a socket of ilium. The other end of femur is attached with tibia and the axis of movement of femur is outside of its substance. This bone plays a vital role in making people run faster and run while holding weight. The femur involves in almost all sports activities that involve running or weight lifting.
Humerus is the upper arm bone which is the second biggest bone in human body. It is the biggest and longest bone in the upper extremity of the body. At the proximal end, humerus has a smooth, thick and large head. This head is connected with a socket which is known as scapula. The other end of humerus is called distal end that is connected to ulna. The head of humerus is attached with scapula in a way that helps in holding the ligaments and muscles together in a strong and systematic manner. Humerus is very strong bone and helps in picking up heavy things and also assists the human body in performing almost all upper body activities in a perfect manner.