Effect of spaceflight on the human body of muscle fibre prominent in muscles also change. Slow twitch endurance fibres used to maintain posture are replaced by fast twitch rapidly contracting fibres that are insufficient for any heavy labour. Advances in research on exercise, hormone supplements and medication may help maintain muscle and body mass. Bone metabolism also changes. Normally, bone is laid down in the direction of mechanical stress. However, in a microgravity environment there is very little mechanical stress. This results in a loss of bone tissue approximately 1.5% per month especially from the lower vertebrae, hip and femur. Due to microgravity and the decreased load
Hyoid bone the mouth and the tongue above, the larynx below, and the epiglottis and pharynx behind. Its name is derived . The hyoid bone is classed as an irregular bone and consists of a central part called the body, and two pairs of horns, the greater and lesser horns. The body of the hyoid bone is the central part of the hyoid bone. The greater and lesser horns () are two sections of bone that project from each side of the hyoid. The greater horns project backward from the outer borders of the body; they are flattened from above downward and