Physiognomy

The term physiognomy refers to features of the body, primarily the face, especially so when, in the narrow sense, these features are used to infer the relatively enduring character or temperament of an individual.

Phrenology

The term phrenology refers to features of the skull and that certain brain areas have localized, specific functions of the mind.  Phrenology is typically referred to as a sub-category of Physiognomy.  Poe deliberately uses elements of both phrenology and physiognomy to enhance the authenticity of his characterizations and to emphasize the indissoluble bond linking the physical to the spiritual and psychological. In addition to their cranial protuberances, Poe's characters reveal their spiritual and psychological tendencies via skin tone, hair texture, clothing, and "airs." (Grayson)  More specifically, Poe utilizes the use of phrenology in his stories The Man of the Crowd and Ligeia.  

This is a picture depicting the different 'compartments' of the brain that depict characteristics.