If a muscle crosses the spinal joints of the trunk posteriorly with a vertical direction to its fibers,what action of the trunk at the spinal joints will it most likely have?
A)flexion
B)extension
C)lateral flexion
D)contralateral rotation

Question

Quizplus · Accepted Answer

A muscle with vertical fibers that crosses the spinal joints of the trunk posteriorly is most likely to be involved in extension of the trunk at the spinal joints. This is because the contraction of the muscle will result in the upward movement of the torso, which is the action of extension. Option A (flexion) is incorrect as this would require a muscle with fibers oriented in a more horizontal direction. Option C (lateral flexion) is also not likely as this would usually require muscles oriented obliquely along the side of the trunk. Option D (contralateral rotation) is also less likely as it would require muscles oriented obliquely with respect to the spine.

If a Muscle Crosses the Spinal Joints of the Trunk