periodontal ligament (PDL), the fibrous connective tissue that surrounds a tooth and attaches the tooth to the alveolus. It is composed of many bundles of collagenous tissue arranged in groups, which lie at differing angles relative to the root of the tooth, the alveolus, and the gingiva due to the forces of mastication, between which lies loose connective tissue interwoven with blood vessels, lymphatic vessels, and nerves. Also called periodontium.
