Milia are small, white cysts commonly seen around the cheeks. Overview. Milia are commonly found on the skin of people of all ages. They are formed when keratin (a substance produced by the skin) becomes entrapped beneath the outer layer of the skin, forming a tiny cyst. An individual milium (the singular of milia) is formed at the base of a hair follicle or sweat gland.
The basic first level structure of cortical bone are osteons. Trabecular bone is much more porous with porosity ranging anywhere from 50% to 90%. It is found in the end of long bones (see picture above), in vertebrae and in flat bones like the pelvis. Its basic first level structure is the trabeculae. III.
The basic unit of Compact Bone is an  osteon , which is also known as a  Haversian System . Each Haversian System (unit) has a cylindrical structure that consists of four parts: 1  A central tube called a Haversian Canal, which contains blood vessels and nerves.2  The Haversian Canal is surrounded by alternate layers of:here are two main types of bone tissue, compact bone and spongy bone. Individual bones in the body can be formed from both of these types of bone tissue. The diagram on the right shows the physical structure of a typical  long bone .