CMTBC Registration Practice Exam

The application of an adduction force to the distal aspect of the forearm is designed to assess the stability of the lateral aspect of the elbow joint. In this context, the lateral collateral ligament plays a crucial role in maintaining stability against varus forces—those that attempt to push the forearm inward towards the body.

When the adduction force is applied, it stresses the lateral collateral ligament, allowing practitioners to evaluate its integrity. If this ligament is compromised, it may not adequately prevent excessive motion that could lead to elbow instability or injury.

The other structures have different functions or are located differently in relation to the forces applied during this assessment. The medial collateral ligament primarily provides support against valgus forces (forces pushing the forearm outward), while the annular ligament stabilizes the radial head during rotations of the forearm. The interosseous membrane, connecting the radius and ulna, helps to transfer loads but does not directly respond to adduction forces. Hence, the lateral collateral ligament is specifically tested with an adduction force applied to the forearm.

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