Diseases of the nose and throat . enoids (Fig. 105). The muscles controlling the movements of the laryngeal cartilagesare divided into two groups, extrinsic and intrinsic. The extrinsic are20 3o6 DISEASES OF THE NOSE AND THROAT. the sternothyroid, the thyrohyoid, the stylo- and palato-pharyngeusand the inferior constrictor of the pharynx. Of the intrinsic mus-cles the cricothyroid is attached to the front and side of the cricoidand to the lower border of the thyroid cartilage. The lower fiberspass to the border of the inferior cornua and act by pulling thecricoid directly backwards while the s
Diseases of the nose and throat . enoids (Fig. 105). The muscles controlling the movements of the laryngeal cartilagesare divided into two groups, extrinsic and intrinsic. The extrinsic are20 3o6 DISEASES OF THE NOSE AND THROAT. the sternothyroid, the thyrohyoid, the stylo- and palato-pharyngeusand the inferior constrictor of the pharynx. Of the intrinsic mus-cles the cricothyroid is attached to the front and side of the cricoidand to the lower border of the thyroid cartilage. The lower fiberspass to the border of the inferior cornua and act by pulling thecricoid directly backwards while the spreading fibers which form therest of the muscle swing the cricoid upon the cricothyroid joints, pull-ing it backwards as well as upwards. Some anatomists erroneouslydescribe the swinging or tilting movement as taking place in thethyroid rather than the cricoid, but most authorities agree that theorigin and fixed point of the cricothyroid muscle are upon the thy-roid cartilage and that therefore the posterior are the movable ends. Fig. 107. Scheme of Action of Posterior Crico-arytenoid Muscles.(Landois and Stirling.) of the vocal bands. For this reason Jurasz advocates calling themuscle thyrocricoid instead of cricothyroid. The practical effect,stretching of the vocal bands, is the same in either case. This mus-cle is a tensor of the vocal bands (Fig. 106). The posterior cricoarytenoid muscle arises from the cricoid car-tilage and is inserted into the outer angle or muscular process ofthe arytenoid cartilage. Its upper fibers rotate the arytenoid whilstthe lower fibers pull the whole mass of the arytenoid outwards. Itis, therefore, a dilator of the glottis, or abductor of the vocal bands(Fig. 107). ANATOMY OF THE LARYNX. 307 The lateral cricoarytenoid muscle springs from the upper borderof the cricoid between the origin of the cricothyroid and the crico-arytenoid articulation, and is inserted into the forepart of the mus-cular process of the arytenoid. It rotates the cartilage
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Keywords: ., bo, bookcentury1900, bookdecade1900, booksubjectnose, bookyear1903
