roll and slide mechanism

Question 1

Concave on convex

Answer 1

Where the 2 surfaces will roll and slide in the same direction

– elbow (ulnarhumeral joint)- flexion and extension

Question 2

convex on concave

Answer 2

Where the 2 surfaces will roll and slide in different directions

– atlantooccipital joint- flexion and extension

– sternoclavicular joint- elevation

– glenohumeral joint- abduction

– wrist carpals- radial and ulnar deviation

– knee flexion into extension and extension into flexion

– talocrural joint- dorsi and plantar flexion

Question 3

Elbow (ulnarhumeral joint)- flexion and extension

Answer 3

Concave on convex

the 2 surfaces will roll and slide into the same direction

Pivot point- capitulum of elbow

Concave surface- ulnar

Convex surface- humerus

Humerus is passive and the ulnar and radius are active where the movement is driven

Flexion- during flexion of the elbow, the ulnar will roll and slide upwards in the same direction

Extension- during extension of the elbow, the ulnar will roll and slide downwards in the same direction

Question 4

Atlantooccipital joint- flexion and extension

Answer 4

Convex on concave

The surfaces will roll and slide in the opposite directions

Convex surface- atlas facet
Concave surface- occipital facet

Passive- C1
Active- Occiput

Flexion- the occipital facet will roll anteriorly and slide posteriorly

Extension- the occipital facet will roll posteriorly and slide anteriorly

Question 5

Sternoclavicular joint- elevation (abduction)

Answer 5

Convex on concave

surfaces roll and slide in opposite directions

Convex- proximal clavicle
Concave- manubrium

Passive- both the manubrium and the clavicle are passive
Active- the movement comes from the GH joint and the scapula

Elevation- when the GH joint abducts, the clavicle will elevate and will rotate towards the sternum and slide downwards

Question 6

Glenohumeral joint- abduction

Answer 6

Convex on concave
2 surfaces will roll and slide in opposite directions

Convex- humeral head
Concave- glenoid fossa of scapula

Passive- scapula is fixed and passive
Active- the humerus drives the movement

Abduction- the head of the humerus will rotate superiorly and slide inferiorly

For this to happen there needs to be healthy rotation and depression of the latissimus dorsi.
There also needs to be depression of the humerus from the subscapularis

There needs to be accompanying rotation of the clavicle