Elastic tissue.

 This form of connective tissue contains a large proportion of elastic fibers. It is found in the walls of arteries and in the air tubes of the respiratory tract and assists in keeping these vessels and passages open. It is also present in certain ligaments, as in the ligamentum sub-flava of the vertebral column where because of its elastic and extensible qualities it materially assists in the performance of sustained muscular effort, as in maintaining the erect position of the spine.