Human Anatomy of the Skeleton

The human skeleton consists of 206 bones. The skeleton is the hard structure to which the soft tissue in the body connects. It also protects the internal organs of the body. Bones contain marrow, which is essential in the production of red blood cells.

Bone

• Bone is hard and holds many minerals, but bone is a living structure and also has blood vessels, nerves and collagen. Two cells are specific to bone. Osteoblasts help with the formation of new bone, and osteoclasts help with the breakdown of old bone. Bones can be long, short, flat or irregular. Long bones are found in the arms and legs such as the humerus or femur. Short bones are found in the wrists and ankles. The two other types of bones are flat bones, such as the cranium, and irregular bones.

The Human Skeleton

• The human skeleton can be divided into the axial skeleton and the appendicular skeleton. The axial skeleton includes the skull, vertebrae, sternum and ribs. The appendicular skeleton includes the bones in the appendages (meaning the arms and legs). There are 22 bones in the head and 33 bones in the spine, including 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar, 5 sacral and 4 in the coccyx. Each arm and leg has approximately 30 bones each, most of which are found in the ankle and wrist.

Function: Movement and Protection

• One of the main functions of the human skeleton is to allow movement and provide protection for the body. Bones are connected together by ligaments, and the muscles are connected to the bone by tendons. The connection of the muscles and skeleton allow movement of the body. In addition, the skeleton protects vital organs such as the heart, brain and lungs.

Function: Mineral Storage

• Bones also help to regulate mineral levels within the human body. Two of the main minerals that it helps to regulate are calcium and phosphorus. When the body has an excess of these minerals, they are stored within the bone. When the body experiences a deficiency of these minerals, they are taken out of the bone and put back into circulation.

Function: Red Blood Cell and Immune Cell Production

• The skeleton also plays a major roll in the immune health of the individual and the production of red blood cells. Bone marrow contains stem cells and is responsible for these two functions. The stem cells in bone marrow can develop to for red blood cells and platelets. The stem cells can also develop to form the cells that make up the immune system, including B-cells and natural killer cells.