How does Jane Austen use imagery in Northanger Abbey?

Imagery:

A family of ten children will be always called a fine family, where there are heads and arms and legs enough for the number; but the Morlands had little other right to the word, for they were in general very plain, and Catherine, for many years of her life, as plain as any. She had a thin awkward figure, a sallow skin without colour, dark lank hair, and strong features — so much for her person; and not less unpropitious for heroism seemed her mind.