The objective of the "Aging Hand" is to give students the opportunity to trace developmental changes in bones of the hand at different ages. Most of the bones that eventually form are made from cartilage. As the child grows, the cartilage changes into bone by a process known as ossification at the sites of growth plates. These ossification areas will help students understand how bone grows in length. This process occurs at set times during the growth of a healthy child. (Refer to "Growth of a Long Bone.") This shows where bone grows in length and in width. Refer to "The Aging Hand" Activity Sheet. The line drawings on these pages were based on x-ray photographs of hands from various females-infant to adulthood. In the x-ray it is easy to detect ossification since the only areas that clearly show up are those formed of bone. The cartilage is almost invisible. In these drawings, students will see the gradual appearance and growth of hand bones as bone replaces "invisible" cartilage. Also in the x-ray, changes in density can be observed as the hand becomes older. However, in the line drawings, these density changes are not seen. To illustrate these changes refer to the drawing showing two metacarpals. One metacarpal shows more bone mass drawn in the shaft of the compact bone (making the medullary cavity appear smaller). The other shows less bone mass in the shaft (making the medullary cavity appear larger). Students will be asked to answer questions from their careful observations.
Photographs of female hands at different ages are used in the activity. Skeletal development is more rapid in women than men. This is apparent at three months of age and becomes more pronounced as men and women grow older. The photographs on which the line drawings were based were from:
Bone, hand, sequencing, x-ray