Conquer the Kaplan Nursing Entrance 2025 – Prep, Practice, and Prosper!

An extensor muscle serves the primary function of extending or straightening the bones at a joint. This is crucial during various movements, such as when straightening the arm at the elbow or the leg at the knee. Extensor muscles work by contracting to pull the bones away from each other, thereby allowing for an increase in the angle between them. This action is fundamental in many daily activities, from walking and running to performing tasks that require reaching out or lifting objects.

In contrast, options that mention bending a joint or contracting involuntarily do not accurately describe the role of extensor muscles. Bending a joint refers to the action of flexor muscles, while involuntary contraction typically pertains to smooth or cardiac muscles, not specifically to extensors. Additionally, the formation of blood cells is a function related to the bone marrow and not to the role of extensor muscles in movement. Understanding the specific role of extensor muscles is essential for grasping how our bodies move and maintain posture.