Final answer:
The angle of pull is the angle between the muscle force vector and the bone it's attached to, affecting the force the muscle can exert. This angle changes with joint movement, affecting muscle length and consequently, force generation. Muscle arrangement and muscle names also contribute to their function and identification.
Step-by-step explanation:
The angle formed by the muscle force vector relative to the bone on which the muscle is attached is known as the angle of pull. This concept is vital in understanding how muscles create movement at the joints. Skeletal muscles are attached to bones via two ends - the origin, which is the fixed, stabilized point, and the insertion, which is the moveable end that pulls on a bone during a muscle contraction.
For example, consider the biceps muscle during forearm flexion (bending the elbow). The brachioradialis and brachialis assist in this movement, acting as synergists to stabilize the insertion point. The prime mover, in this case, is typically the biceps brachii, which exerts a force that changes with the angle of the elbow joint. An increase in angle results in a lengthened bicep muscle, allowing it to exert more force than when it is shorter and contracted rigidly.
Moreover, the arrangement of the muscle fibers, known as fascicles, and their various configurations, such as parallel, circular, and pennate, affect the muscle's range of motion and force generation capability. Muscle names often reflect characteristics like location, shape, or the bones associated with the origin and insertion, such as the gluteal muscles, tibialis anterior, and pectoralis major.