Articular System 1 - Introduction

Question 1

Define joint or articulation?

Answer 1

A joint or articulation is the site where two or more bones meet.

Question 2

What is the function of joints?

Answer 2

1. Uniting bones to bones, bone to cartilage, cartilage to cartilage, bone with teeth.
2. Provide mobility.
3. Resist various forces including compression, tension and shear stress. (CTS)

Question 3

Identify the joints of the body?

Answer 3

Question 4

How are joints classified?

Answer 4

1. Based on the type of connective tissue that binds the articulating surfaces of the bones.
2. Whether a space occurs between the articulating surfaces.

Question 5

Classify joints structurally?

Answer 5

Fibrous (no movement):
Occurs where bones are united by dense regular (fibrous) connective tissue

Cartilaginous (some movement):
Occurs where bones are united by cartilage.

Synovial (no movement):
1. Has a fluid-filled cavity that separates the cartilage-covered articulating surfaces of the bone.
2. Articulating surfaces are enclosed within a capsule and the bones are also united by various ligaments.

Question 6

Classify joints functionally?

Answer 6

Question 7

Describe the function and provide examples of fibrous joints - Gomphoses?

Answer 7

Function:
2. Allow microscopic movements = allows us to determine how hard we bite or if there is something stuck in between our teeth.

Location:
1. Between the roots of individual teeth and the sockets of the mandible or maxilla.

Question 8

Describe the function and provide examples of fibrous joints - Sutures?

Answer 8

Function:
1. Immovable = protective adaptation.

Location:
1. Adult skull

Question 9

What is a fontanelle?

Answer 9

Gaps between the cranial bones filled with membranous connective tissue.

Question 10

Describe the general structure and provide examples of fibrous joints - Syndesmoses?

Answer 10

Structure:
1. United by short dense connective tissue fibers but are not interlocked.
Function:
Slight movement.

Location:
1. Between the bones of the forearm (radius and ulna) and the leg (tibia and fibula).

Question 11

Label the fontanelles of the neonatal skull?

Answer 11

Question 12

What do cartilaginous joints contain and how can you differentiate between the 2 types?

Answer 12

1. Contain a pad of cartilage that is wedged between the ends of bones.
2. Depending on the types of cartilage.

Question 13

Describe the general structure and provide examples of cartilaginous joints - synchondroses?

Answer 13

Structure:
Bones are united by hyaline cartilage.

Examples:
1. Epiphyseal (growth) plate of long bones in children.

2. Adults = first sternocostal joint between the manubrium of the sternum and the costal cartilage of the first rib.

Question 14

Describe the general structure and provide examples of cartilaginous joints - Symphyses?

Answer 14

Structure:
Bones are lined with hyaline cartilage, which in turn are fused to an intervening pad of fibrocartilage.

Function:
Slight movement.

Example:
1. Intervertebral discs.

2. Pubic symphysis.

Question 15

Label the vertebrae?

Answer 15

Question 16

Label the diagram below of a synovial joint?

Answer 16

Question 17

What are the 2 layers of the articular capsule of a synovial joint and what are they made of?

Answer 17

Fibrous (outer) layer:
Structure = Made of dense connective tissue.
Function = Strengthens the joint to prevent the bones from being pulled apart.

Synovial (inner) membrane:
Structure = Made primarily of areolar connective tissue.
Function = Produces the synovial fluid that fills the joint cavity.

Question 18

Describe the structure and function of the joint cavity and articular cartilage of the synovial joint?

Answer 18

Joint Cavity:

Structure:
The space between the articular surfaces of the bones of a synovial joint.
Movement:
Space = movement, the type and degree of rotation.

Articular Cartilage:

Structure:
Layer of hyaline cartilage covering the articular surfaces of the bones of a synovial joint.
Function:
1. Reduces friction.
2. Prevents damage to the articulating bone surfaces.
3. Acts as a shock absorber.

Question 19

Describe the structure and function of the ligament of the synovial joint?

Answer 19

Structure:
1. Made of dense regular connective tissue.

Function:
1. Support the stability of synovial joints by preventing movements in undesirable directions and limiting the range of normal movements.

Question 20

What are the 3 main factors responsible for the stability of of joints?

Answer 20

1. Articulating bone shapes.
2. Static stabilisers (capsule, ligaments, intracapsular structures)
3. Dynamic stabilisers (muscles surrounding and acting at the joints).

Question 21

Explain what a ‘bursa’ and ‘tendon sheaths’ are?

Answer 21

Bursa:
Fibrous sacs lined with synovial membrane inside that contain a small amount of synovial fluid.

Tendon Sheaths:
Elongated bursae that wrap around tendons.

Question 22

Define uniaxial, biaxial, and multiraxial synovial joint types?

Answer 22

Uniaxial:
Movement in one plane.

Biaxial:
Movement in two planes.

Multiaxial:
Movement in all three planes.

Question 23

Label the synovial joint types?

Answer 23

Question 24

What are the definitions for the synovial joint types - plane, pivot, hinge, saddle, condyloid and ball-and-socket?

Answer 24

Plane = the flattened surface of one bone articulates with a similar surface of another bone.

Pivot = rounded surface of one bone fits into a ring formed by a ligament and another bone.

Hinge = convex surface of one bone articulates with the concave surface of another bone.

Saddle = saddle-shaped surface of one bone articulates with a similar surface of another bone.

Condyloid = oval surface of one bone articulates with the depressed oval surface of another bone.

Ball-and-socket = round head of one bone articulates with the cup-shaped depression of another bone.

Question 25

What are the functions for the synovial joint types - plane, pivot, hinge, saddle, condyloid and ball-and-socket?

Answer 25

Plane = gliding movements.
Pivot = rotation around a central axis.
Hinge = flexion and extension in the sagittal plane around a transverse axis.
Saddle = flexion/extension and abduction/adduction.
Condyloid = flexion/extension and abduction/adduction.
Ball-and-socket = flexion/extension, abduction/adduction, medial/lateral rotation and circumduction.

Question 26

Name the examples of movement allowed by synovial joints?

Answer 26

Flexion, Extension, Lateral Flexion.

Abduction, Adduction.

Circumduction, Opposition/Reposition.

Rotation, Pronation, Supination.

Elevation, Depression, Protraction, Retraction.

Dorsiflexion, Plantarflexion, Inversion, Eversion.

Question 27

Lisa the 3 factors influencing the stability of joints?

Answer 27

Articular Surfaces:
Shapes of the articular surfaces determine the movements allowed at a joint.

Ligaments:
Unite the bones and prevent excessive or undesirable movements.

Muscle Tone:
Are kept taunt and are the most important factor in joint stability.

Question 28

What tissue covers the articular surfaces in synovial joints & what tissue makes up ligaments?

Answer 28

Hyaline cartilage

Dense regular connective tissue