. The anatomy of the horse, a dissection guide. Horses. 228 THE ANATOMY OF THE HORSE. elastic fibres connecting it to the thyroid ; but in the horse this action is assisted by the hyo-epiglottideus muscle. THE MUSCLES OF THE LAEYNX. Extrinsic Group.—This includes the sterno-thyroid, the thyi'O-hyoid, and the hyo-epiglottideus. The last of these is a single muscle; the other two are double. The Steeno-THYROID Muscle (Fig. 26). See page 146. The Thyro-hyoid Muscle (Figs. 26 and 27). This is a dark-coloured, fleshy nuiscle taking origin from the thyroid cornu (heel process) of the hyoid bone, and
. The anatomy of the horse, a dissection guide. Horses. 228 THE ANATOMY OF THE HORSE. elastic fibres connecting it to the thyroid ; but in the horse this action is assisted by the hyo-epiglottideus muscle. THE MUSCLES OF THE LAEYNX. Extrinsic Group.—This includes the sterno-thyroid, the thyi'O-hyoid, and the hyo-epiglottideus. The last of these is a single muscle; the other two are double. The Steeno-THYROID Muscle (Fig. 26). See page 146. The Thyro-hyoid Muscle (Figs. 26 and 27). This is a dark-coloured, fleshy nuiscle taking origin from the thyroid cornu (heel process) of the hyoid bone, and inserted into an oblique line on the outer surface of the thyroid wing. Action.—Acting alone, the thyro-hyoid muscles would elevate the larynx between the thyroid cornua of the hyoid bone ; but when they act in concert with the sterno-thyroid, the thyroid cartilage will be steadied, and will serve as the fixed point for the crico-thyroid and thyro- arytenoid muscles. The Hyo-epiglottideus Muscle (Fig. 27) takes migin from the upper face of the body of the hyoid bone; and passing back- wards in the middle line, it is inserted into the anterior surface of the epiglottis at its lower part. Its fibres are mixed with a quan- tity of fatty-elastic tissue. Action.—To assist the natural elasticity of the epiglottis in restoring the cartilage to the erect position at the close of the act of deglutition. Intrinsic Group.—This includes four pairs of muscles, viz., the crico-thyroid, the thyro-arytenoid, the posterior crico-arytenoid, and the lateral crico-arytenoid; and a single muscle—the arytenoid- eus. The Ceico-thyroid Muscle (Fig. 26) arises from the side of the cricoid cartilage; and its fibres, passing obliquely upwards and back- wards, are inserted into the lower edge of the thyroid wing. Action.—This, muscle acts on the crico-thyroid joint, increasing the tension of the vocal cord by increasing the distance between the fore- part of the thyroid and the base of the ar
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Keywords: ., bookcentury1800, bookdecade1880, booksubjecthorses, bookyear1884
