What is Anatomy of Bones ?

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The bones are connected together in such a manner as to form joints or articulations and are bound firmly together at these joints by strong white fibrous bands called ligaments. The muscle are united to the bones by other bands called tendons. The difference between ligaments and tendons is that ligaments bind bone to bone whereas tendons bind muscle to bone. Inside the joint, the bones are covered with a slick, somooth material that is called articular cartilage. Articular cartilage is the material that allows bones to move against one another in the joints of the body. The cartilage lining is about ¼ - inch thick in most weight-bearing joints such as the ankle, hip or knee. It is soft enough to allow for shock absorption but tough enough to last as long as it is not injured. This cartilage is again covered with a membrane called the synovial membrane. From this membrane, a fluid called synovial fluid comes out to lubricate the joints. 

As bones are connected together to form joints, these joints can be classified as movable or immovable. Immovable joints are those in which bones are in actual contact such as joints in the skull. Movable joints are those in which bones forming them are capable of moving against each other. 

Movable Joints are again Divided into Two Types 

1) Perfect Joints 
• Gliding joints in which bones slide over each other, e.g., ankle and wrist joint.
• Ball and socket joints having a round head that rotate in a hollow socket, e.g., shoulder and hip joint.
• Pivot joints in which a projection of one bone serves as a pivot for the rotation of the other, e.g., atlas and axis.

2) In Imperfect Joints, The bones do not move on each other but all motion is due to flexibility of the layer of cartilage between them. The vertebrae with intervertebral cartilages form such joints. 

In the upper limb, one end of the clavicle articulates with the top of the sternum and the other end forms a joint with the scapula and humerus. The outer end of the clavicle articulates with one of the two processes, which project from the top of the scapula, and is attached to other processes by means of strong ligaments. At the upper and inner part of the scapula, a shallow concave surface called glenoid cavity receives the rounded head of the humerus. The joint thus formed has greater movement than any other joint in the body. The lower end of the humerus forms a hinge joint with the ulna. The ulna also has a projection behind the humerus forming olecranon process, which prevents the forearm moving too far back. The humerus is also attached to the radius as its lower end. The lower end of the radius gives attachment of the bones of the wrist. The wrist is composed of eight small bones called carpal bones, which are united by means of ligaments. The other end of the wrist is attached to five long bones called metacarpal bones, which form the palm of the hand. The metacarpal bones are then attached to palanges, which form bones of the fingers. Read Previous   Read More...