Articular system

Overview:

The main components of the articular system are:

==Ligaments:== Band of fibrous tissue that connects 2 bones and provides attachment for the cartilage, fascia and muscle.

%%Tendons:%% Connects the muscle of the bone.

^^Cartilage:^^ Fibrous tissue that covers the ends of bones, can withstand great amounts of pressure and tension and also provides a cushion for the joint.

Joints are points of contact between 2 or more bones. Joints can be classified into 3 types,

==Cartilaginous joints== which are slightly moveable (e.g. intervertebral disks). Cartilaginous joints also include fibrocartilage or hyaline (articular) cartilage between the 2 bones.

$Fibrous joints$, which are not moveable (sutures of the skull). Fibrous joints also have a thin layer of fibrous periosteum between the 2 bones.

^^Synovial joints^^ which are totally moveable and often sites of movement-related Injuries. These injuries include the knee and shoulder. Synovial joints can also

·       All synovial joints contain these 7 common components

·       Synovial fluid for joint lubrication and nutrition

·       Articular cartilage to spread out and absorb forces

·       Articular capsule to surround and protect the joints

·       Synovial membrane to produce the fluid for the joint

·       Capsular ligaments to limit excessive joint motion

·       Blood vessels to provide nutrients, permits healing to occur

Sensory nerves transmit pain and awareness of position (proprioception)

Functions:

There are three main functions of the articular system:

1. To allow motion of the musculoskeletal system
2. To bear weight
3. To hold the skeleton together

Types:

There are 6 different types of joints in the human body. These are the ==gliding joints== @@hinge joints@@, $pivot joints$, %%Condyloid%% or ^^ellipsoidal joints^^, @@saddle joints@@ and ^^ball and socket^^

==Gliding joints:==

·       Articular surfaces are essentially flat

·       Allow only slipping or gliding movements

·       Only examples of non-axial- joints

·       E.g., intercarpal/intertarsal joints, vertebral articular processes

@@Hinge joints:@@

·       Cylindrical projections of one bone fits into a through shaped surface on another

·       Motion is along a single plane (like a mechanical hinge)

·       Uniaxial joints permit flexion and extension only

·       Examples: Elbow and interphalangeal joints

$Pivot joints:$

·       Rounded end of one bone protrudes into a “sleeve.” Or ring, composed of bone (and possible ligaments) of another

·       Uniaxial rotation of one bone around its own long axis

·       Examples: “No” motion of the head via joint between the 2nd and 3rd vertebra

Condyloid or ellipsoidal joints:

·       Oval articular surface of one bone fits into a complementary depression in another

·       Both articular surfaces are oval

·       Biaxial joints permit all angular motions

·       Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle) joints

%%Saddle joints:%%

·       Similar to condyloid joints but allow greater movement

·       Each articular surface has both a concave and a convex surface

·       Example: carpometacarpal joint of the thumb

^^Ball-and-socket joints:^^

·       A spherical or hemispherical head of one bone articulates with a cup like socket of another

·       Multiaxial joints permit the most freely moving synovial joints

·       Examples: shoulder and hip joints

Growth and Maturation:

The older we get the cartilage around our bones and joints starts to deteriorate naturally. The smooth tissue and cushions joints and help them move more easily and disappears with age. We are essentially wearing out the body’s natural shock absorbers. In addition, we lose muscle tone and bone strength as we get older. This means that our articulation (joints) system bears more stress.

Examples of joints

Some familiar joints are

·       Skull

·       Intervertebral discs

·       Shoulder

·       Elbow

·       Wrist

·       Thumb

Metacarpophalangeal (knuckle joint)