1 . Sitting in your chair and straightening your leg (moving from a flexed knee

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Question

1. Sitting in your chair and straightening your leg (moving from a flexed knee to an extended knee) is an example of?

a concave joint surface moving on a convex joint surface

a convex joint surface moving on a concave joint surface

2. Performing the up phase of a triceps extension (moving from a flexed elbow to an extended elbow) is an example of

a concave joint surface moving on a convex joint surface

a convex joint surface moving on a concave joint surface

a concave joint surface moving on a convex joint surface

a convex joint surface moving on a concave joint surface

The movement of joints is also known as "Arthrokinematic movement" & the science is Arthrokinematics.

1. if a person sitting in his chair (flexed knee) and straightening his leg (extended knee) is an example of a concave

joints surface moving on a convex surface. Since knee joint is a " Tibio-femoral articulation", in which concave

tibial( related to tibia bone) plateaus articulates on the convex femoral condyles(grooves of femur bone).

When posterior part of this joint glides, it increases flexion and while tibiofemoral anterior glides it performs

extention.

2. Performing the up phase of a triceps or moving from a flexed elbow to an extended elbow is an example of a

convex joint suface moving on a concave surface. Since this is a type of "Humero-radial articulation". in that

convex capitulum of humerus bone articulates with the concave radial head( head of radius bone).

Dorsal or posterior gliding of radius bone increases elbow extention while ventral or anterior glide of head of the

radius increases elbow flexion.

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