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Joints are flexible connections of bones. There are many different types of joints in the human body, effecting a maximum of flexibility.

All in all, more than 200 bones of the human skeleton are connected with each other by joints. They differ in type of joint and flexibility. In addition, there is also a differentiation of synovial joints and fibrous and cartilaginous joints, complicating the precise counting of joints. The flexibility of joints is very different. There are several movement axes: stretching and bending, adducting and abducting, outer and inner rotation. The full range of motion is not given to every joint. This depends upon the structure of the joints.

Fibrous and cartilaginous joints are cartilaginous or fibrous connections, permitting a certain flexibility (i.e. connection between sacral bone and ilium bone, cranial bone, rib cartilage). There is no big flexibility for these joint connections. Therefore, they are called fibrous and cartilaginous joints.

A synovial joint is always built according to the same principal: two ends of a bone, which are separated by a joint cavity, build joint head and socket. There is a cartilage between the two partners of any joint in the joint cavity, working as antishock pad and protecting the articular surfaces. Furthermore, articular disks can be embedded in the joint cavity, which compensate the imbalance of socket and joint head.

These joints are surrounded by ligaments and the joint capsule, which is filled with synovial fluid.

All in all, there are about 360 joints. If you only count synovial joints, there are just over 100 in the human body. 


Synovial joints can be divided into different groups (types of joints):

  • The ball and socket joint: This type of joint makes movements possible around an indefinite number of axes. The shoulder and hip joints are typical ball and socket joints.
  • The saddle joint: This type of joint makes the movement around two axes possible in the thumb basal joint. A rotation around the longitudinal axis is not possible.
  • The hinge joint: This type of joint can be found in the elbow joint. Movements around one axis are possible (with two main movement directions: bending and stretching).
  • The condyloid jointor: It is a joint with two ovoid joint parts. This type is biaxial and can be found, i.e., between skull and first cervical vertebra.
  • The pivot joint: It is a joint between the first two cervical vertebras. These are connected by a pivot joint and can only move around one axis.


          Ball and socket joint    Condyloid jointor                 Saddle joint                    Hinge joint                            Pivot joint

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