The stuff that is seen under the drawing, that defines the figure has been broken down in steps below.
What I'll call "deep layer muscles" (most of these aren't really but they are about as deep as we're going to go. Erector Spinae describes the whole of the muscle group (including sacrospinalus) running along the spine which keeps the body upright and pulls the upper torso back into position after being pulled downward/inward from the Abdominials etc. Rhomboid (minor and major) inserts into the medial edge of the scapula and infraspinatus, teres minor and teres major make up part of the rotator cuff.
Latissimus dorsi originate along the spine and top portion of top of the pelvis, the largest muscle of the back which acts to bring the humerus backward or if the humerus is in a locked position, brings the rest of the back toward the humerus (think pull-up).
Trapezius make up the visible back of the neck, originating up from the lowest point on the ribcage and the ribs and inserting into the back (occiciptal region) of the skull.