Final answer:
Coordinated movement at the elbow joint involves the biceps and triceps muscles functioning as a flexor-extensor pair, respectively. The muscles apply force to the bones they are connected to via tendons, thus moving the joint effectively as a lever system.
Step-by-step explanation:
Coordinated movement in the human body, particularly at the elbow joint, requires the precise action of skeletal muscles working in pairs across joints. These muscle pairs consist of a flexor, such as the biceps, and an extensor like the triceps. When the biceps muscle contracts, it pulls on the forearm causing the elbow to flex, or bend. Conversely, when the triceps contract, the elbow extends or straightens.
The contraction of muscles provides the effort or force in our musculoskeletal system, analogous to a lever system. Muscles attach to bones via tendons very close to the joints, acting as fulcrums, thereby creating a mechanical advantage that allows for effective movement. This setup ensures that while muscles exert large forces within the body, they efficiently translate these into movement at the limb with lesser force, albeit over a greater distance.
Furthermore, other muscles can assist in the movement by stabilizing adjacent structures or resist the action to control the motion smoothly. This intricacy in muscle arrangement allows us to perform complex and precise movements needed for all activities in our daily lives, from the utmost basic such as walking and sitting to those requiring fine motor skills.