Sacrum

Anatomy

The sacrum is a single wedge-shaped bone formed by the fusion of five sacral vertebrae. In childhood, the sacral vertebrae are separated by intervertebral discs in much the same manner as the upper parts of the spinal column. However, around the age of 20 these vertebrae start to fuse by ossification of the discs. This is a gradual process and it is not uncommon for ossification to only be completed up to or even beyond 40 years. The sacrum is wider in proportion to the length in females although the first sacral vertebra (S1) is larger in males.

continue reading Sacrum and Coccyx (Tailbone) of the Spine Anatomy and Pictures

Human bones are hard and rigid structures that develop during life as cartilaginous tissue in fetal life is gradually replaced with bone tissue. Eventually this tissue undergoes calcification which makes it hard and strong. Throughout life the bone is undergoing remodeling due to the action of bone cells like osteoblasts and osteoclasts. The bone tissue is maintained by another bone cell known as an osteocyte. In order to make bone, osteoblasts keep depositing osteoid tissue which becomes calcified. Simultaneously osteoclasts are resorbing this bone. However, the rate of deposition and resorption are kept in balance so that there is not an excess nor deficiency of bone mineral. To maintain normal bone mineralization, the body needs an adequate supply of calcium and phosphate. This is derived from the food (dietary intake) when it is absorbed from the gut. Vitamin D plays an important role in calcium absorption from the gut and also on bone mineralization. When there is a deficiency of vitamin D, these processes are affected and leads to diseases of the bones.

continue reading Osteomalacia (Adults) or Rickets (Children) – Soft Bone Disease

There is often a misconception that bone is a calcified mass that is ‘dead’ and lacks sensation. However, bone is very much a living part of the body which is constantly undergoing remodeling. It is covered by a fibrous sheath known as periosteum which is rich in blood vessels and nerves. Some of these nerves accompany nutrient arteries into the interior of bone through haversian canals. The bone therefore has sensory abilities and the presence of pain receptors (nociceptors) on the periosteum means that pain from the bone is possible.

Being a hard structure under normal circumstances means that the injury to bone has to be significant to elicit pain. Since bones are often covered by muscles, connective tissue, fat and skin, these structure are more likely to be the source of the pain particularly in an injury. Subchondral   bone tissue is covered by cartilage that forms part of a joint, which are more prone to injury and pain than bone tissue itself. With regards to the musculoskeletal system in general, pain more often emanates from the muscles and joint than from the bone. However, when there is bone pain, particularly acute, it is excruciating.

continue reading Bone Pain (Osteodynia) Location, Symptoms and Causes

Bones are important structures of the body that plays a role in protecting the soft tissue and serves as a lever for muscles. The human skeletal system is made up of 206 bones in the adult. These bones can be categorized as part of the axial skeleton or appendicular skeleton. The bones of the axial skeleton include the skull, vertebral column and ribcage. The appendicular skeleton bones include those of the upper and lower limbs, as well as the bones that connect the axial and appendicular skeleton like the pelvic bone.

There are number of diseases that may affect the bones and disrupt the normal bone structure. Human bone is made up of three parts – mineral, matrix and cells. The bone mineral is calcium phosphate crystals deposited as hydroxyapatite. The bone matrix is made up on an outer compact tissue which is hard and inner spongy cancellous tissue. There are three types of bone cells – osteoblasts, osteocytes and osteoclasts – are responsible for forming, shaping, maintaining and resorbing bone. The constant activity of these cells and the interplay of its different functions are responsible for maintaining the the structural integrity of bone.

continue reading Osteoporosis Pathophysiology, Causes, Signs and Symptoms

The skeletal system is made up of some 206 bones in adults which provides form for the soft tissues of the body, protection and a hard lever structure for the muscles. Bones are much more than calcified masses that are present in various shapes and is living tissue just like any other part of the body. These are dynamic components of the body that are constantly undergoing resorption, renewal and remodeling to maintain its shape, structure and strength.

Bones develop in fetal life, first as a cartilaginous framework (anlage). This cartilage is subsequently removed while bone tissue is laid down concurrently (endochondral ossification) in most bones. A similar process known as intramembranous ossification occurs in flat bones. Bone itself is composed of an inorganic mineral component and organic matrix component. Blood vessels, nerves, cartilage and bone marrow that all interact with bone tissue may not be considered as bone but are essential for the formation and maintenance of bone tissue.

continue reading Human Bone Anatomy, Structure, Cells and Formation