Mother is related to Earth. Earth is related to Place. Bed is a type of Place. 
Head is related to Hand. Hand is related to Limb. Thigh is a type of Limb. Thigh is related to Neck. 
Mother <--RelatedTo--> Earth <--RelatedTo--> Place <--IsA-- Bed 
Head <--RelatedTo--> Hand <--RelatedTo--> Limb <--IsA-- Thigh <--RelatedTo--> Neck 