S1) Bones and Joints Flashcards
What is a joint?
A joint / articulation is a point of contact between neighbouring bones, between cartilage and bones, or between teeth and bones
Which factors are affected by the structural characteristics of a specific joint?
- Strength
- Magnitude of movement
- Types of movement
What are the three main categories of joints?
Describe the structure and function of fibrous joints and provide some examples
- Structure: lack a synovial cavity, articulating bones are held very closely together by fibrous connective tissue
- Function: permit little/no movement
- E.g. skull sutures, inferior tibiofibular joint, posterior sacroiliac joint*
State the structure and function of cartilaginous joints
- Structure: lack a synovial cavity, articulating bones are tightly connected by cartilage
- Function: permit little/no movement
There are two types of cartilaginous joints.
Identify and describe them
- Primary cartilaginous joints: hyaline cartilage connecting tissue e.g. epiphyseal plate
- Secondary cartilaginous joints (symphyses): fibrocartilage disc as connecting tissue e.g. pubic symphysis
What are 5 important characteristics of synovial joints?
- Joint cavity
- Articular cartilage
- Articular capsule (two layers)
- Rich blood and nerve supply
- Accessory ligaments (extracapsular & intracapsular)
Identify and describe the two layers of the synovial joint capsule
- Outer fibrous capsule (may have accessory ligaments)
- Inner synovial membrane (secretes lubricating synovial fluid)
Identify the 6 different types of synovial joints
Identify and describe the general types of movement that occur at synovial joints
- Gliding movements: articulating surfaces slide across each other
- Angular movements: change in the angle between articulating bones (flexion, extension, abduction, adduction, circumduction)
- Rotation: a bone turns around its own longitudinal axis (medial rotation, lateral rotation)
Describe the structure and function of planar joints and provide an example
- Structure: articulating surfaces are flat / slightly curved (non-axial joint)
- Function: gliding movements occur
- E.g. sternoclavicular joint*
Describe the structure and function of hinge joints and provide some examples
- Structure: convex surface of one bone fits into the concave surface of another bone (mono-axial joint)
- Function: flexion and extension occur
- E.g. knee joint, elbow joint, ankle joint*
Describe the structure and function of pivot joints and provide an example
- Structure: rounded/pointed surface of one bone articulates within a ring formed by another bone and a ligament (mono-axial joint)
- Function: rotation occurs
- E.g. atlanto-axial joint (C1 and C2)*
Describe the structure and function of condyloid (ellipsoidal) joints and provide an example
- Structure: oval-shaped condyle of one bone rests against the elliptical cavity of another bone (bi-axial joint)
- Function: flexion, extension, abduction, adduction, circumduction occur
- E.g. wrist joint*
Describe the structure and function of saddle joints and provide an example
- Structure: articular surface of one bone is saddle-shaped and articular surface of the other bone resembles the legs of a rider sitting in a saddle (bi-axial)
- Function: movement is less restricted
- E.g. CMCJ between trapezium the base of metacarpal I*
Describe the structure and function of ball-and-socket joints and provide two examples
- Structure: ball-like surface of one bone rests against the cuplike depression of another bone (poly-axial)
- Function: flexion, extension, abduction, adduction, circumduction, rotation occur
- E.g. shoulder and hip joints*
Identify and describe the 6 special movements which occur only at certain joints
- Elevation&depression – upward and downward movement of the mandible
- Protraction&retraction – mandible or shoulder girdle move forward and backward parallel to the ground
- Inversion&eversion – sole of foot moves medially and laterally
- Dorsiflexion&plantar flexion – bending of the ankle joint
- Supination&pronation – forearm turns anteriorly and posteriorly
- Opposition – movement of the thumb across the palm
What are the 5 factors affecting contact and range of motion at synovial joints?
- Structure/shape of the articulating bones
- Strength&tension of the joint ligaments
- Arrangement&tone of muscles around the joint
- Apposition of neighbouring soft tissues
- Disuse of a joint
What drives the effects of ageing on joints?
The effects of ageing on joints are variable among individuals and are affected by genetic factors and wear and tear
Identify 5 effects of ageing on synovial joints
- Decreased production of synovial fluid
- Thinning of articular cartilage
- Shortening of ligaments
- Decrease in ligamentous flexibility
- Degenerative changes in load-bearing joints
