MUSCULAR SYSTEM. 101 



superiorly, to a tendinous line running along the superior part of 

 the pharynx. 



CONSTRICTOR PHARYNGis POSTERIOR. — Crico-pharyngcus. 



Situation. — Postero-superior part of the pharynx. 



Atlachinent. — Inferiorly, its fibres are confounded with those 

 of the muscular coat of the oesophagus : superiorly, to the lateral 

 parts of the cricoid cartilage. 



llelatioiis of the three Constrictors. — ^u^pexxoxXy, with the 

 guttural pouches; inferiorly, with the membranous parietes of the 

 pharynx, with the os hyoides, and the thyroid and cricoid carti- 

 lages ; laterally, with the anterior portions of the parotid gland. 



Structure of them. — Fleshy. 



Actio)!, of them. — To constrict or contract the cavity of tiie 

 pharynx in the act of deglutition. 



9.— LARYNGEAL REGION. 

 Comprehending eight pairs and one single muscle. 



HYO-THYROIDEUS. 



Situation. — Upon the side of the larynx. 



Form. — Quadrilateral : flat and thin. 



Attachment. — To the inferior border of the semicircular por- 

 tion of the OS hyoides ; and to a broad eminence upon the postero- 

 inferior part of the side of the thyroid cartilage. 



Action. — To elevate the thyroid cartilage, and with it the 

 larynx altogether ; or, to depress the os hyoides. 



CRICO-THYROIDEUS. 



Situation. — Upon the postero-lateral part of the larynx. 



Form. — Flat; triangular. 



Attachment. — To the borders and side of the cricoid cartilage; 

 and to the posterior border of the thyroid, filling up the vacuity 

 between the two cartilages. 



Action. — To approximate the two cartilages. 



CRICO-ARYTENOIDEUS POSTICUS. 



Situation. — Upon the upper part of the larynx. 



Attachment. — To the entire upper surface of the cricoid carti- 

 lage, and to the posterior angle of the arytenoid cartilage. 



Structure. — Fleshy ; and furnished with two small tendons, 

 which are fixed to the arytenoid. 



Action. — To draw the arytenoid cartilage backwards. 



CRICO-ARYTENOIDEUS L AT ERA LIS. 



Situation. — Postero-lateral and superior parts of the larynx, 

 between the thyroid and cricoid cartilages. 



