Types of Joints
Joints of human beings can be classified on different bases. Each base divides joints into different categories. There are three types of classifications of joints; Structural classification, Functional classification, and Regional classification. Lets have a look at all of these.
In this type of joints the bones are joined together by means of fibrous tissue. Due to the presence of fibrous tissue these joints are either immovable or permit movement to a very little extent. Fibrous joints are further divided into the following subtypes;
- Sutures: These are peculiar to skull and are immovable. According to the shape of the bony margin the sutures may be;
- Plane sutures
- Serrate sutures
- Denticulate sutures
- Squamous sutures
- Limbous sutures
- Syndesmosis: In this type of fibrous joints the bones are connected with interosseus ligament for example the inferior tibiofibular joint.
- Gomphosis: These are also known as peg and socket joints. Examples are tooth in the socket.
In this type of joints there is a piece of cartilage between the bones which hold the bones together and makes a joint. Cartilaginous joints are further divided into the following subtypes;
- Primary cartilaginous joints: (synchondrosis): In this subtype the bones are united by a plate of hyaline cartilage so that the joint is immovable and strong. These joints are temporary in nature because after a certain age the cartilaginous plate is replaced by the bone. Examples of this type of joints are joint between the epiphyses and diaphysis of a growing long bone, the costochondral joint and the first chondrosternal joint.
- Secondary cartilaginous joints: (symphysis): These are also known as fibro-cartilaginous joints. There articular surface is covered by a thin layer of hyaline cartilage and the bones are united by fibro-cartilage. These joints are permanent and persist throughout the life of an individual. Typically the secondary cartilaginous joints occur in the median plane of the body and permit limited movements because of compressible pad of cartilage in them. The thickness of the fibro-cartilage in these joints is directly related to the range of movement the joint offers. Examples of this type of joints are; symphysis pubis, manubrio-sternal joint and intervertebral joints between the vertebral bodies.
Synovial joints are most evolved and therefore most mobile type of joints. Visit the page: Synovial Joints for more detail.
Immovable joints: (Synarthroses)
They are fixed joints at which there is no movement. The articular surfaces are joined by tough fibrous tissue. Often the edges of the bones are dovetailed into one another as in the sutures of the skull.
Partially moveable joints: (Amphiarthroses)
They are joints in which slight movement is possible. A pad of cartilage lies between the bone surface and there is a fibrous capsule to hold the bone and cartilage in place. The cartilages of such joints also act as shock absorbers for example the intervertebral discs between the bodies of vertebrae where the cartilage is strengthened by extra collagen fibers.
Freely moveable joints: (Diarthroses)
They are the synovial joints of structural classification. They are freely moveable though at some of them the movement is restricted by the shape of the articulating surfaces and by the ligaments which hold them together. These ligaments are of elastic connective tissue.
Skull type: They are the joints of the skull and are immovable
Vertebral type: They are the joints of vertebral column and are slightly moveable
Limb type: They are the joints of upper and lower limbs and are freely moveable.