DUODENUM (L. _duodeni_, twelve). The twelve-inch intestine; so called from its being equal in length to the breadth of twelve fingers. The first portion of the small intestines, beginning from the pylorus. DURA MATER (_hard-mother_). The outermost membrane of the brain. E EFFLUVIA (L. _effluo_, to flow out). Exhalations, vapors, &c. ELASTICITY. The property or power by which a body compressed or extended returns to its former state. ENAMEL. The hard exterior surface of the teeth. ENCEPHALON (Gr. _èn_, in, _kephalē_, the head). The brain; the contents of the skull, consisting of the cerebrum, cerebellum, medulla oblongata, and membranes. EPIDERMIS (Gr. _epi_, upon, and _dérma_, the skin) The cuticle, or scarf-skin; the thin, horny layer which protects the surface of the integument. EPIGLOTTIS. A cartilage of the larynx, situated above the glottis. EPIPLOON (Gr. _plēo_, to sail). The omentum; a membranous expansion which _floats_ upon the intestines. EPITHELIUM (Gr. _títhēmi_, to place). The cuticle on the red part of the lips, and on the mucous membranes in general. EXCRETION (L. _excerno_, to separate from). A general term for the perspiration, fæces, &c., which are separated and voided from the blood or the food. EXPIRATION (L. _expiro_, to breathe). That part of the respiration in which the air is expelled. Compare _Inspiration_. EXUDATION. _Transpiration._ The flow of liquid from the surface of the skin or membrane, an ulcer, &c. F FACIAL (L. _facies_, the face). Belonging to the face; as _facial nerve_, _facial vein_, &c. FALX. A scythe or sickle. The _sickle_-like processes of the dura mater, situated between the lobes of the cerebrum and cerebellum. FASCIA (L. _fascis_, a bundle). Literally, a scarf or large band. Hence it is applied to the aponeurotic expansion of a muscle. FASCICULUS (L. dim. of _fascis_, a bundle). A little bundle; a handful. Thus, a muscle consists of _fasciculi_ of fibres. FAUCES. The gullet or upper part of the throat; the space surrounded by the vellum palati, the uvula, the tonsils, and the posterior part of the tongue. FEMUR, FEMORIS. _Os femoris._ The thigh-bone; the longest, largest and heaviest of all the bones of the body. FIBRE (L. _fibra_, a filament). A filament or thread, of animal, vegetable or mineral composition. FIBRIL. A small filament or fibre, as the ultimate division of a nerve. The term is derived from _fibrilla_, L. dim. of _fibra_, a filament. FIBRIN. A tough, fibrous mass, which, together with albumen, forms the basis of muscle. FIBRO-CARTILAGE. Membraniform cartilage; a substance intermediate between proper cartilage and ligament. FILAMENT (L. _filum_, a thread, _forma_, likeness). Thread-like; applied to the papillæ at the edges of the tongue. FISSURE. A cleft; a longitudinal opening.