THE LARYXX 



903 



The posterior border, thick and rounded, projects above and below into the 

 superior and inferior eornua, and gives partial insertion to the stylo- and palato- 

 pharvngei muscles. 



The superior eornua jiroject inwards as well as ui)wards and backwards. To 

 their tijis are attachefl the thyro-liyoid ligaments, and near root of each appears the 

 tultcrcle at tlic upi)cr end of the oblique line. 



The inferior eornua are short, blunt processes. The}' project inwards as well 

 as downwards and forwards. By means of small oval concave facets (directed 

 downwards as well as inwards) placed on their inner faces, the inferior eornua 

 articulate with the facets on the sides of the cricoid cartilage. They give partial 

 attachment to the inferior constrictors of the pharynx and crico-thyroid muscles in 

 addition to the ligaments of the joint. 



The CRICOID CARTILAGE is thick and strong, and forms a complete ring around 

 the lower part of the larynx. Behind, it presents a quadrate surface, but narrows 



Fig. 524.— Side View of the Cartilages of the Laeyxx. (Modified from 



Bourgery and Jacob.) 



Thyro-hyoid membrane 



SUPERIOR BORDER OF THYROID 



Crico-thyroid rauBcle 

 Crico-thyrojd membrane 

 median portion 



Crico-thyroid muscle 



THIRD RING OF TRACHEA 



Thyro-hyoid ligament 



CARTILAGO TRITICEA 



SUPERIOR CORNU 



Superior tubercle 

 Stylo-pharyngeus and 

 palato-pharyngeus 



Thyro-hyoid muscle 



SURFACE OF ALA OVERLAPPED BY 

 INFERIOR CONSTRICTOR 



Stemo-thyroid muecle and 

 inferior tubercle 



Inferior constrictor 



rapidly in its anterior half to only one-fourth or one-fifth of its posterior de)>th. 

 Hence its comparison to a signet ring. It thus possesses an anterior and a posterior 

 portion, and a superior and inferior border, and presents four articular surfaces. 



The posterior quadrate portion is divided behind by a median vertical ridge 

 which separates two broad and shallow depressions. To this ridge some of the 

 longitudinal fibres of the oesophagus are attached, and the depressions give origin 

 to the posterior crico-arvtenoid muscles. 



The anterior portion is narrow and rounded, and gives attachment in front to 

 the crico-thyroid muscles, and more posteriorly to some iil»res of the inferior 

 constrictor of the pharynx. 



Between these two halves of the ring, Init nearer the lower border, is jdaced the 

 oval surface (looking upwards and outwards) for articulation with the inferior cornu 

 of the thyroid cartilage. 



The inner surface is smooth and lined bv mucous membrane. 



