Classification of Joints

Question 1

What are the two ways joints are classified?

Answer 1

1) By the type of tissue present

2) By the degree of movement permitted

Question 2

What is a joint?

Answer 2

Defined as a connection between two bones in the skeletal system

Question 3

Fibrous Joints

Answer 3

Where the bones are bound by a tough, fibrous tissue

These are typically joints that require strength and stability over range of movement

Further subclassified into sutures, gomphoses and syndesmoses

Question 4

Sutures (Fibrous Joints)

Answer 4

Immovable joints (aka synarthrosis) and are only found between the flat, plate-like bones of the skull

There is limited movement until approx. 20 years of age after which they become fixed and immobile

This limited movement is most important at birth, allowing deformation of skull as it passes through birth canal

Question 5

Gomphoses (Fibrous Joints)

Answer 5

Also immovable joints (aka synarthrosis)

They are found where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth)

Question 6

Syndesmoses (Fibrous Joints)

Answer 6

Slightly moveable joints (aka amphiarthrosis)

They are compromised of bones held together by an interosseous membrane (a thick dense fibrous sheet of connective tissue that spans the space between two bones)

For example the middle tibiofibular joint

Question 7

Synarthrosis

Answer 7

Immovable joint

Question 8

Amphiarthrosis

Answer 8

Slightly moveable joint

Question 9

Diarthrosis

Answer 9

Freely moveable joint

Question 10

Cartilaginous Joints

Answer 10

The bones in the joint are united by fibrocartilage or hyaline cartilage

There are 2 main types: synchondroses (primary cartilaginous) and symphyses (secondary cartilaginous)

Question 11

Synchondroses (Primary Cartilaginous Joints)

Answer 11

The bones are connected by hyaline cartilage

These are immovable joints (synarthrosis)

Question 12

Symhyses (Secondary Cartilaginous Joints)

Answer 12

The bones are connected by a layer of fibrocartilage

They are slightly movable (amphiarthrosis)

Question 13

Synovial Joint

Answer 13

Defined by the presence of a fluid-filled joint cavity contained within a fibrous capsule

They are freely moveable (diarthrosis) and are the most common type of joint found in the body

Can be sub-classified depending on the shape of their articular surfaces (joint connection surface): hinge, saddle, plane, pivot, condyloid, ball & socket

Question 14

Hinge (Synovial Joint)

Answer 14

Permits movement in one place- usually flexion and extension

E.g. elbow joint, ankle joint, knee joint

Question 15

Saddle (Synovial Joint)

Answer 15

Characterised by opposing articular surfaces with reciprocal concave-convex shapes (like a horse and its saddle)

E.g. carpometacarpal joints (where fingers meet hands)

Question 16

Plane (Synovial Joint)

Answer 16

The articular surfaces are relatively flat, allowing the bones to glide over one another

E.g. acromioclavicular joint, subtalar joint

Question 17

Pivot (Synovial Joint)

Answer 17

Allows for rotation only, it is formed by a central bony pivot which is surrounded by a bony-ligamentous ring

E.g. proximal and radionular joints, atlantoaxial joint

Question 18

Condyloid (Synovial Joint)

Answer 18

Contains a convex surface which articulates with a concave elliptical cavity, aka ellipsoid joints

E.g. wrist joint, metacarpophalangeal joint, metatarsophalangeal joint

Question 19

Ball & Socket (Synovial Joint)

Answer 19

Where the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone

It permits free movement in numerous axes

E.g. hip joint, shoulder joint