Classification Of Joints

Question 1

Fibrous Joints

Answer 1

Bones concerned are bound by tough fibrous tissue- strength joints.
Further classified into sutures, gomphoses, and syndesmoses.

Question 2

Sutures

Answer 2

Type of fibrous joint.
These are immovable joints only found bw the flat plate-like bones of the skull.
Limited movement until about 20yrs of age, after which they become fixed. They are most important at birth as at that stage they are not fused, allowing deformation of the skull as it passes through the birth canal.

Question 3

Gomphoses

Answer 3

Immovable joints and are found where the teeth articulate with their sockets in the maxillae (upper teeth) or the mandible (lower teeth)
The fibrous connection that binds the tooth and socket is the periodontal ligament

Question 4

Syndesmoses

Answer 4

Slightly movable joints. Structure is comprised of bones held together by an interosseous membrane.
Key in providing strength along long bones, preventing them from separating
Eg: Middle radio-ulnar and middle tibio-fibular joint

Question 5

Cartilaginous

Answer 5

In cartilaginous joints, the bones are attached by fibrocartilage or hyaline cartilage.
There are 2 main types: Primary cartilaginous and cartilaginous secondary joints.

Cartilage is an excellent shock absorber as it is essentially a thick gel. Important in the pelvis and spine.

Question 6

Synchondroses

Answer 6

Also known as primary cartilaginous joints. They only involve hyaline cartilage. The joints can by immovable or slightly movable.
Eg: joint bw the diaphysis and epiphysis of a growing long bone.

Question 7

Symphyses

Answer 7

Also know as a secondary cartilaginous joint, it can involve fibrocartilage or hyaline cartilage.
These joints are slightly movable
Eg: pubic symphysis

Question 8

Synovial

Answer 8

Joint filled with synovial fluid. These joints tend to be fully movable and are the main type of joint found around the body.
Allow a huge range of movements, which are defined by the arrangement of their surfaces and the supporting ligaments and muscles.
Often classified by their movement: hinge, saddle, plane, pivot, condyloid, ball and socket.

Question 9

Hinge joint

Answer 9

Permits flexion and extension

Eg: Elbow

Question 10

Saddle Joint

Answer 10

Concave and convex joint surfaces unite at saddle joints.

Eg. Metatarsophalangeal joint (toes)

Question 11

Plane Joint

Answer 11

Permit gliding or sliding movements

Eg: acromioclavicular joint ( collarbone to shoulder blade)

Question 12

Pivot joint

Answer 12

Allows rotation. A round bony process fits into a bony ligamentous socket.
Eg: Atlantoaxial (top of neck) and proximal radio-ulnar joint (elbow)

Question 13

Condyloid

Answer 13

Permits flexion, extension, addiction, abduction, and circumduction
Eg: metacarpophalangeal joint

Question 14

Ball and socket joint

Answer 14

Permits movement in several axis; a rounded head fit into a concavity
Eg: Glenohumeral joint (shoulder)

Question 15

Stability of joints- Shape, size, and arrangement of articular surfaces.

Answer 15

Most important factor is the relative proportion of 2 articulating surfaces. For example, in the shoulder joint, the humeral head is disproportionately larger than the glenoid fossa or the scapula that it sits in making the joint more unstable as there is less contact bw bones.
In contrast the acetabulum of the pelvis fully encompasses the femoral head which makes the hip more stable. However, while the hip is more stable, the should has more ROM.

Question 16

Stability of joints - ligaments

Answer 16

Ligaments prevent excessive movement that could damage the joint. As a general rule, the more ligaments a joint has and the tighter they are, the more stable the joint is.

Ligaments can stretch, tear or even damage the bone they attach to.

Question 17

Stability of joints - tone of surrounding muscles

Answer 17

Eg: support provided by the rotator cuff muscles, which keep the head of the humerus in the shallow glenoid cavity of the scapula. If there is loss of tone, such as old age or stroke, the shoulder can dislocate. (Dislocations can tear the rotator cuff muscles making the person more susceptible to further injuries.）

Also important for knee stability. Inappropriate or unbalanced training can cause the knee to be prone to injury through muscle imbalance. This can lead to chronic pain.