tooth morphology trait periodontal ligament morphology trait VT:0003668 EFO:0007780 Trait.ontology Any measurable or observable characteristic related to the shape, structure, color or pattern of the fibrous connective tissue that surrounds the root of a tooth, separating it from and attaching it to the alveolar bone; normally extends from the base of the gingival mucosa to the fundus of the bony socket, and its main function is to hold the tooth in its socket.