FRC Functional Anatomy & Biomechanics

Question 1

According to the convex-concave rule, when a convex joint surface moves on a fixed concave surface, how do roll and glide relate?

Accepted Answer

Roll and glide occur in opposite directions

Answer

A convex surface moving on a fixed concave surface rolls one way and glides the opposite way.

Question 2

During glenohumeral abduction, which way does the humeral head glide on the glenoid?

Accepted Answer

Inferiorly

Answer

The convex humeral head rolls superiorly and glides inferiorly to remain centered during abduction.

Question 3

In open-chain knee extension, the concave tibial plateau moves on the convex femur; which way does the tibia glide?

Accepted Answer

Anteriorly

Answer

With concave-on-convex motion, roll and glide occur in the same direction, so the tibia glides anteriorly.

Question 4

What is the close-packed position of the tibiofemoral joint?

Accepted Answer

Full extension with tibial external rotation

Answer

The knee is close-packed in full extension with external rotation of the tibia, where congruency and ligament tension are maximal.

Question 5

Which term describes the movement of bones through space as seen from outside the body, such as flexion or abduction?

Accepted Answer

Osteokinematics

Answer

Osteokinematics describes gross bone movement through planes, while arthrokinematics describes motion between joint surfaces.

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