Page:The New International Encyclopædia 1st ed. v. 11.djvu/871

LARYNGITIS. losis. The symptoms are hoarseness or complete loss of voice, pain in the throat, increased by coughing, speaking, or swallowing. Laryngoscopic examination reveals an unnatural pallor of the laryngeal mucous membrane and the presence of small ulcers. The prognosis for recovery in this form is unfavorable. The treatment consists in local applications of lactic acid, solution of nitrate of silver, etc. For croupous laryngitis, see

LARYN'GOSCOPE (from Gk., larynx, larynx + , skopein, to look). An instrument composed of two mirrors and employed for the examination of the throat. The laryngoscope was devised by Kobert Liston, but was much improved and first practically employed by Czerniak. The two mirrors are called the laryngoscopic mirror and the head-mirror. The laryngoscopic mirror is a small circular mirror placed on a stalk attached to its margin, at an angle of from 120° to 150°, the stalk being about six inches in length, and being composed of flexible metal, so that it can be bent at the will of the operator. The head-mirror is a large reflecling mirror, about four to six inches in diameter, with a central opening through which the observer looks. It is attached to a spectacle frame by a stiffly working ball-and-socket joint, or, better, to a band passing about the forehead. The rays from an electric light or from a good lamp are concentrated by means of this reflector on the laryngeal mirror, which is placed against the soft palate and uvula. The larvngeal mirror, introduced with the right hand. is maintained at such an inclination that it throws the light downward and illuminates the parts to be examined, while at the same time it reflects the images of the parts into the eye of the observer through the central opening of the reflector. By this means he can look through the larynx into the trachea or windpipe. The tongue, covered with a hand-kerchief or with a small towel, is held lightly with the left hand and thus kept out of the way. By means of this instrument we can see the actual position of small tumors, ulcers, etc., and ascertain the color and condition of the nuieous membrane lining the first part of the respiratory tract. The .same arrangement is also very fre- quently employed in examination of the posterior aspect of the nasal cavities.

LAR'YNGOT'OMY (Gk., from . larynx, larynx + , -tomia, a cutting, from , temnein, to cut). A medical term signifying the operation of cutting into the larynx (q.v.). This operation is performed in some cases of dipththeria by preference over tracheotomy (q.v. ). when for special reasons the trachea is to be avoided. Laryngo-tracheotomy is the term applied to an incision made through the lower part of the laryngeal cartilages and extending down into the trachea. The incision in each ease is made for the purpose of placing in position a tube through which the patient breathes while the glottis is closed by the disease.

LAR'YNX (Noo-Lat., from Gk. larynx, larynx). The organ of voice. It also takes a part in the respiratory process, as all air passing either to or from the lungs must pass through it. It is a complex piece of mechanism resembling a box composed of pieces of cartilage, which may be moved on each other, and inclosing the membranous bands (the choralæ vocales) by which the vocal vibrations are produced. It is situated between the trachea, or windpipe, and the base of the tongue, at the upper and front part of the neck, where it forms' a considerable projection (especially in men) in the middle line; it opens superiorly into the pharynx, or throat, and interiorly into the windpipe. The cartilages of which the skeleton of the larynx is composed are nine in number; viz. the thyroid and the

hy.b., Hyoid bone: ''th. hy. mem., thyro-hyoid membrane; th. car., thyroid cartilage; c. Th. mem., crico-thyroid membrane; rs. tra. rings of trachea; th. hy. lig.'', thyro-liyoid lig:ainent; ''sup. cor., superior cornu; s. tub., superior tubercle; s. w., surface of wing overlapped by inferior constrictor; inf con.'', inferior constrictor. cricoid cartilages, the epiglottis, the two arytenoid and the two cuneiform cartilages, and the two corniciila hiryngis. The thyroid (Gr., shield-like) cartilage consists of two square plates of cartilage united in front at an acute angle, which forms the projection which is commonly known as the pomium Adami, or Adam's apple. Each of these plates is prolonged at the upper and lower posterior corners. The thyroid cartilage forms almost the whole of the anterior and lateral walls of the larynx.

The cricoid (Gr., ring-like) cartilage is a ring whose lower margin is parallel to the first ring of the trachea, to which it is united by fibrous membrane. Its upper border is connected in front with the lower border of the thyroid cartilage by a thick yellow fibrous tissue. It presents two articular surfaces on either side; viz. a lower one, which articulates with the inferior cornua of the thyroid cartilage, and an upper one. which is oval in form and supports an arytenoid cartilage. The arytenoid (Gr., ladle-like) cartilages are pyramidal bodies resting on the oval articular surfaces at the upper and posterior part of the cricoid cartilage. When in situ, they present a concave posterior surface. From their connection with the vocal cords, and from their great mobility as compared with the two larger cartilages, the arytenoids play a very important part in the mechanism of the larynx. The epiglottis is a very flexible cartilaginous valve, situated at the base of the tongue, and covering the opening of the larynx. Its direction is vertical, except during deglutition, when it becomes horizontal. It is attached inferiorly. by a kind of pedicle, to the angle of the thyroid cartilage. Upon removing the investing mucous membrane, the cartilage is found to be perforated