Short video of the back muscles on the posterior torso (superficial, intermediate, deep)
Identifies:
Superficial
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboid minor
Rhomboid major
Intermediate
Serratus posterior superior (not shown)
Serratus posterior inferior
Deep
Splenius capitus
Semispinalis capitus
Erector spinae group
Rotators