ANATOMY OF THE LARYNX 



513 



TABLE OF THE SEVERAL GROUPS OF THE INTRINSIC MUSCLES OF THE LARYNX AND 



THEIR ATTACHMENTS. 



Group Muscle 



I. 



Abductors. 



II. and III. 

 Adductors 



and 

 Sphincters. 



Attachments 



Action 



Crico-aryt- This pair of muscles arises, on either side, 

 enoidei from the posterior surface of the cor- 

 postici. responding half of the cricoid cartilage. 

 From this depression their fibers con- 

 verge on either side upward and out- 

 ward to be inserted into the outer angle 

 of the base of the arytenoid cartilages 

 behind the cricoarvtenoidei laterales. 



Draw inward and 

 backward the outer 

 angle of arytenoid 

 cartilages, and so 

 rotate outward the 

 processus vocalis and 

 widen the glottis. 



In three 

 layers: 



a. Outer 

 layer, 

 Thyro- 

 aryepi- 

 glottici. 



A pair of muscles. Flat and narrow, Help to narrow or 

 which arise on either side from the pro- close the rima 

 cessus muscularis of the arytenoid car- glottidis. 

 tilage, then passing upward and inward 

 cross one another in the middle line to 

 be inserted into the upper half of the 

 lateral border of the opposite arytenoid 

 cartilage and the posterior border of the 

 cartilage of Santorini. The lower fibers 

 run forward and dowmvard to be in- 

 serted into the thyroid cartilage near 

 the commissure. The fibers attached 

 to the cartilage of Santorini are con- 

 tinued forward and upward into the 

 aryepiglottic fold. 



b. Middle 

 layer. 



i. Aryte- 

 noideus 

 posticus. 



A single muscle. Half-quadrilateral, 

 attached to the borders of the arytenoid 

 cartilages, its fibers running horizontally 

 between the two. 



ii. Thyro- A pair of muscles. Each of which con- 

 arytenoi- sists of three chief portions. The 

 d e i ex- lower and principal fibers arise from the 

 terni. lower half of the internal surface of the 



thyroid cartilage, close to the angle, and 

 from the fibrous expansion of the crico- 

 thyroid ligament, and are inserted into 

 the lateral border of the arytenoid car- 

 tilage. The inner fibers to the lower 

 half of this border, and the outer fibers 

 into the upper half, some pass to the 

 cartilage of Wrisberg and the ary- 

 epiglottic fold. 



Draws together the 

 arytenoid cartilages 

 and also depresses 

 them. When the 

 muscle is paralyzed, 

 the inter-cartilagin- 

 ous part of the cords 

 cannot come t o - 

 gether. 



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