Types of joint

Joints are classified according to the degree of movement possible at each one. There are three main joint classifications:

• fibrous - no movement is possible (also known as fixed joints)

• cartilaginous - slight movement is possible

• synovial — freely moveable joints.

Fibrous joints

These are immovable joints with tough fibrous tissue between the bones. Often the edges of the bones are dovetailed together into one another, as in the sutures of the skull. Some examples of fibrous joints include the joints between the teeth and between the maxilla and mandible of the jaw.

Student activity

Now complete Activity 3.3 in the resources for this book on Dynamic Learning Online.

Fig 3.13 A fibrous joint

Cartilaginous joints

These are slightly movable joints which have a pad of fibrocartilage between the end of the bones making the joint. The pad acts as a shock absorber.

Some examples of cartilaginous joints are those between the vertebrae of the spine and at the symphysis pubis, in between the pubis bones.

- Intervertebral disc pTr O on r^r-aCi cn -L , .-V_

- Intervertebral disc pTr O on r^r-aCi cn -L , .-V_

Fig 3.14 A cartilaginous joint

Synovial joints

These are freely movable joints which have a more complex structure than the fibrous or cartilaginous joints. Before looking at the different types of synovial joints it is important to have an understanding of the general structure of a synovial joint.

The general structure of a synovial joint

Synovial Joint

Fig 3.15 A synovial joint

• A synovial joint has a space between the articulating bones which is known as the synovial cavity.

• The surface of the articulating bones is covered by hyaline cartilage which is supportive to the joint by providing a hard-wearing surface for the bones to move against one another with the minimum of friction.

• The synovial cavity and the cartilage are encased within a fibrous capsule which helps to hold the bones together to enclose the joint. This joint capsule is reinforced by tough sheets of connective tissue called ligaments which bind together the articular ends of bones.

The joint capsule is reinforced enough to allow strength to resist dislocation but is flexible enough to allow movement at the joint.

The inner layer of the joint capsule is formed by the synovial membrane which secretes a sticky oily fluid called synovial fluid which lubricates the joint and nourishes the hyaline cartilage.

As the hyaline cartilage does not have a direct blood supply, it relies on the synovial fluid to deliver its oxygen and nutrients and to remove waste from the joint which is achieved via the synovial membrane.

Ball and socket joint

Hinge joint

Ball and socket joint

Hinge joint

Condyloid joint

Condyloid joint

Pivot joint

Pivot joint

Saddle joint Fig 3.16 Types of synovial joint

Gliding joint

Types of synovial joints

Synovial joints are classified into six different types according to their shape and the movements possible at each one. The degree of movement possible at each synovial joint is dependent on the type of synovial joint and its articulations.

Type of synovial joint

Description

Movement

Example

Ball and socket

Formed when the rounded head of one bone fits into a cup-shaped cavity of another bone

Allows movement in many directions around a central point; flexion, extension, adduction, abduction, rotation and circumduction

Hip and shoulder joints

Hinge

Where the rounded surface of one bone fits the hollow surface of another bone

Movement is possible in only one plane; allows flexion and extension

Knee and elbow joints, joints in between the phalanges

Condyloid

The joint surfaces are shaped so that the concave surface of one bone can slide over the convex surface of another bone in two directions

Although a condyloid joint allows movement in two directions, one movement dominates. Movements possible include flexion, extension, adduction and abduction

Wrist joint and joint between the metacarpals and phalanges (metacarpophlangeal joints)

Gliding

Often referred to as synovial plane joints as they occur where two flat surfaces of bone slide against one another

Allow only a gliding motion in various planes (side to side/back and forth)

Joints between vertebrae and sacroiliac joint

Pivot

Occurs where a process of bone rotates in a socket; one component is shaped like a ring and the other component is shaped so that it can rotate within the ring

Only permits rotation

Joint between the first and second cervical vertebrae (atlas and axis) and joint at the proximal ends of the radius and the ulna

Saddle

Shaped like a saddle; articulating surfaces of bone have both rounded and hollow surfaces so that the surface of one bone fits the complementary surface of the other

Movements possible at this joint include flexion, extension, adduction, abduction and a small degree of axial rotation

Thumb joint

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

Get My Free Ebook


Responses

  • michelino lettiere
    What are the six types of synovial joints?
    2 years ago

Post a comment