The articular system "joints" شرح المفاصل وانواعها

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Articular system
Joints are the areas where 2 or more bones meet. Most joints are mobile, allowing the bones to move. Joints consist of the following: Cartilage. This is a type of tissue that covers the surface of a bone at a joint
They make the skeleton flexible - without them, movement would be impossible. Joints allow our bodies to move in many ways
Joints can be classified by the type of the tissue present (fibrous, cartilaginous or synovial)
A fibrous joint is where the bones are bound by a tough, fibrous tissue. These are typically joints that require strength and stability over range of movement.
Fibrous joints can be further sub-classified into sutures, gomphoses and syndesmoses.
Sutures are immovable joints (synarthrosis), and are only found between the flat, plate-like bones of the skull.
There is limited movement until about 20 years after which they become fixed and immobile. They are most important in birth, as at that stage the joints are not fused, allowing deformation of the skull as it passes through the birth canal.
Gomphoses
Gomphoses are also immovable joints. They are found where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth)
Syndesmoses
Syndesmoses are slightly movable joints
They are comprised of bones held together by an interosseous membrane. The middle radioulnar joint and middle tibiofibular joint are examples of a syndesmosis joint.
Classification by type of tissue
Fibrous - bones connected by fibrous tissue.Cartilaginous - bones connected by cartilage.Synovial - articulating surfaces enclosed within fluid-filled joint capsule
Fibrous Joints
A fibrous joint is where the bones are bound by a tough, fibrous tissue. These are typically joints that require strength and stability over range of movement.
Fibrous joints can be further sub-classified into sutures, gomphoses and syndesmoses.
Sutures
Sutures are immovable joints (synarthrosis), and are only found between the flat, plate-like bones of the skull.
There is limited movement until about 20 years of age, after which they become fixed and immobile. They are most important in birth, as at that stage the joints are not fused, allowing deformation of the skull as it passes through the birth canal
Gomphoses
Gomphoses are also immovable joints. They are found where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth).
The tooth is bound into its socket by the strong periodontal ligament.
Syndesmoses
Syndesmoses are slightly movable joints (amphiarthroses).
They are comprised of bones held together by an interosseous membrane. The middle radioulnar joint and middle tibiofibular joint are examples of a syndesmosis joint.
Cartilaginous
In a cartilaginous joint, the bones are united by fibrocartilage or hyaline cartilage.
There are two main types: synchondroses (primary cartilaginous) and symphyses (secondary cartilaginous).
Synchondroses (primary cartilaginous joints )
In a synchondrosis, the bones are connected by hyaline cartilage. These joints are immovable (synarthrosis).
An example of a synchondrosis is the joint between the diaphysis and epiphysis of the long bones
Symphyses (secondary cartilaginous joints)
Symphysial joints are where the bones are united by a layer of fibrocartilage. They are slightly movable (amphiarthrosis).
Examples include the pubic symphysis, and the joints between vertebral bodies.
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A synovial joint
is characterised by the presence of a fluid-filled joint cavity contained within a fibrous capsule. It is the most common type of joint found in the human body, and contains several structures which are not seen in fibrous or cartilaginous joints
Types of synovial joints according to axes of movement
1-Uniaxial
movement take place around single axis (elbow joint )
2- Biaxial
movements take place around two axes (wrist joint)
3- Multiaxial
movements occur around more than 2 axes (shoulder joint)
Synovial joints are subdivided based on the shapes of the articulating surfaces of the bones that form each joint. The six types of synovial joints are pivot, hinge, ellipsoid saddle, plane, and ball-and socket-joints
1-Hinge( elbow joint)
2- Pivot (proximal radioulnar joint)
3- Ellipsoid ( wrist joint)
4- Saddle (Carpometacarpal joint of the thumb )
5- Ball and socket (shoulder/ hip joints)
6- plane (sternoclavicular joint)