Diaphragm

(di'a-frăm.) (Gr. diaphragm a, literally a partition - wall.] (Anat.) A large muscular membrane stretched transversely between the thoracic and abdominal cavities, which it separates from each other. When it contracts, its fibres become straight, the chest is enlarged, and the abdomen diminished. It is then an inspiratory muscle. It may also diminish the capacity of the chest, and be an expiratory muscle. The muscle plays an important part in sighing, yawning, coughing, sneezing, laughing, sobbing, crying, hiccoughing, singing, vomiting, and in the excretion of fæces and urine, .-(Opt.) A circular ring, or annulet, used in some kinds of optical instruments. Diaporesis, (dī-a-por-ē'sis.) [Gr., perplexity. ] (Rhet.) A figure expre ive of the speaker's doubt or hesitation as to the manner in which he should proceed in his discourse, the subjects of which he has to treat being all of equal significance or importance. [s. 284]