ANTERIOR ASPECT OF HEAD AND NECK. 



inner surface and lower margin of thyroid ; (posterior, or hori- 

 zontal part) anterior aspect of inferior cornu of thyroid carti- 

 lage. [968] 



Posterior Crico-arytenoid. Origin; depression on posterior 

 lamina of cricoid beside the mesial ridge. Insertion; poste- 

 rior surface of muscular process of arytenoid. [969] 



Lateral Crico-arytenoid. Origin ; upper border of lateral part 

 of anterior arch of cricoid, in front of the arytenoid facet; 

 lateral part of crico- thyroid membrane. Insertion; anterior 

 surface of muscular process of arytenoid. [969] 



Thyro-arytenoideus Externus. Origin; lower half of inner 

 surface of thyroid ala; lateral part of crico- thyroid membrane. 

 Insertion; outer border and muscular process of arytenoid; 

 Arytenoideus transversus. Some of the uppermost fibres curve 

 upward (Thyro-epiglottideus) to the aryteno-epiglottidean 

 fold and margin of the epiglottis. [969] 



Thyro-arytenoideus Internus. This lies under and is more 

 or less united with the preceding ; it is prismatic and lies on the 

 outer side of the true vocal cord. Origin ; angle between thy- 

 roid alse. Insertion; outer aspect of vocal process and de- 

 pressed part of antero-external surface of arytenoid; outer 

 side of true vocal cord (as the Ary-vocalis) . [970] 



Arytenoideus Obliquus. Origin; posterior aspect of muscu- 

 lar process of arytenoid. Course; across the opposite muscle. 

 Insertion; summit of opposite arytenoid; aryteno-epiglottid- 

 ean fold (as the Aryteno-epiglottideus). [970] 



Arytenoideus Transversus. This unpaired muscle lies under 

 the preceding. It consists of transverse fibres connecting the 

 arytenoids behind, attached to the posterior aspect of the 

 outer border of each and, in part, continuous with the Thyro- 

 arytenoideus externus. [970] 



Trachea. This fibre-muscular tube is kept open by a series 

 of cartilaginous rings, which are deficient posteriorly and are 

 embedded in its walls. It begins opposite the lower border of 

 the sixth cervical vertebra and descends in the median line to 



[93] 



