Articulations

What’s an articulation?

it’s a joint, which is a site where two or more bones meet.

Now, joints are classified in two ways:

1. By structure

2. By function

Structure Fibrous Cartilaginous Synovial
Function Synarthrosis Amphiarthrosis Diarthrosis

These categories interrelate in the sense that:

Fibrous joints are synarthrotic, meaning they are generally immovable joints

Cartilaginous joints are generally amphiarthrotic which is defined as a semi movable joint

Synovial joints are characterized as diarthrotic which means they are freely moveable.

Now lets get into detail:

Fibrous joints

Fibrous joints are made of dense fibrous connective tissue and there is no joint cavity present. There are three different types of fibrous joints:

1. Suture

2. Syndesmosis

3. Gomphosis

 

Moving onto Cartilaginous joints:

Much like the synovial joints, cartilaginous joints don’t have a joint cavity. Instead of dense fibrous connective tissue, cartilaginous joints are comprised of cartilage which connects articulating bones. These types of joints are not highly moveable and are usually classified as amphiarthrotic. There are two different types of cartilaginous joints:

1. Synchondrosis:

2. Symphysis:

Lastly, Synovial joints are defined as articulating bones separated by a fluid containing joint cavity. This is what sets synovial joints apart from cartilaginous joints and fibrous joints. Additionally, synovial joints are diarthrotic which means they are freely movable.

The components of a typical synovial joint include:

articular cartilage- lines the ends of bones in a joint

articular capsule-  encloses the joint cavity of a synovial joint.

synovial fluid- lubricates the joint surfaces and nourishes articular cartilages.

synovial cavity

reinforcing ligaments

nerve endings

Stabilizing factors:

1. Deep sockets

2. Close fit of articular surfaces

3. More ligaments

4. Muscle tone

Structures of the synovial joints:

Function Structure
Bursae act as cushion or buffer flattened fibrous sacs filled with synovial fluid
Tendon Sheaths reduce friction elongated tubelike bursae which wraps around tendons
Articular fat pads act as a cushion between fibrous capsule and synovial membrane or bone
Menisci Separate articular surfaces fibrocartilage pads

And there you have it. Joints and articulations in a nutshell, hope you enjoy 🙂

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