Value

Achromatic:  A- meaning "without", chroma- meaning "intensity of color". Without hue (Blacks, grays, and whites).

Midtones, shadows and light were used to create this composition. 

There's value but there's no hue.

Chiaroscuro: Italian word for the technique of using shadows and light. to create depth.

Chiaroscuro is just a fancy word to express the use of value to crate a 3-D object in a 2-D space.

Cross-Hatching: technique of adding depth to a composition that uses lines to add value.

The neck, tail, and back limbs are the areas where cross-hatching is seen the clearest.