In human anatomy, what is the basic action of any muscle?

Bending the trunk forward (spinal flexion), such as when performing an abdominal crunch, primarily uses which muscle?

Which action is primarily performed by the iliopsoas muscle at the hip joint?

What is the primary action of the quadriceps femoris muscle group at the knee joint?

What is the primary action of the transversus abdominis muscle?

Which action is primarily performed by the infraspinatus muscle at the glenohumeral (shoulder) joint?

What is the primary action of the gracilis muscle at the hip joint?

Which of the following is an action of the external abdominal oblique muscle?

In standard anatomical position, what is the primary action of the erector spinae muscle group when contracting bilaterally?