JOINTS OF THE LARYNX 



1213 



the hyo-thyreoid ligament. Its posterior surface above is saddle-shaped; below, 

 it is convex, presenting the epiglottic tubercle [tuberculum epiglotticum]. To 

 the margins are attached the ary-epiglottic folds. The epiglottic cartilage 

 presents numerous small holes and depressions for the accommodation of glands. 

 The cuneiform cartilages (of Wrisberg) [cartilagines cuneiformes (Wrisbergi*)] 

 (fig. 973) lie as small, rod-like bodies in the ary-epiglottic folds anterior to the 

 corniculate cartilages. They are variable in form and size and not rarely absent 

 altogether. 



These cartilages are parts of the epiglottic cartilage in some mammals where, as in man, 

 they he in the ary-epiglottic folds. Their relations to the arytsenoids are regarded as secondary. 

 Sutton has shown that in the ant-eater a continuous rim of yellow elastic cartilage extends 

 from the sides of the epiglottic cartilage to the summits of the arytajnoids. A minute unpaired 

 interarytcenoid or procricoid cartilage is rarely present imbedded in the cricopharyngeal ligament 

 and covered by the pharyngeal mucosa. It is a constant structure in certain mammals. A 

 pair of small sesamoid cartilages, also constantly present in some mammals, is occasionally 

 found in man at the lateral margins of the arytsenoids, connected with them and with the 

 corniculate cartilages by elastic ligaments. 



Structure of the cartilages. — The thyreoid, cricoid, and greater part of the arytsenoid are 

 composed of hyaline cartilage; the epiglottic, corniculate, and cuneiform cartilages, as well as 

 the apex and vocal process of the arytaenoid, are of elastic cartilage. Certain parts of the laryn- 

 geal skeleton normally undergo calcification and subsequent ossification. Calcification begins 

 at about twenty years of age in the thyreoid and cricoid cartilages, and later in the arytsenoid. 

 The process begins a little later in the female than in the male, and does not extend so rapidly. 

 The extent to which the cartilages are ossified and the time occupied in the process vary con- 

 siderably. The elastic elements are not involved in the process. 



Fig. 975.- 

 FiG. 976.- 



-Cricoid and Aryt.enoid Cartilages seen from Before. 

 -Cricoid and Aryt.enoid Cartilages seen from the Left. 



(Rauber-Kopsch.) 

 (Rauber-Kopsch. ) 



Ary-corniculate 

 synchron. 



Triangxilax pit .- 

 Oblong pit„. 



Corniculate cart. 



Apex of arytaenoid 

 Colliculus 

 ' Arcuate crest 



Muscular 

 process 

 Vocal process 



Ary-corniculate synchondrosis 

 Corniculate 



Thyreoid 

 articular 

 surface 



THE JOINTS AND FIBROUS MEMBRANES OF THE LARYNX 



(1) Connections between the Laryngeal Cartilages 



The crico -thyreoid articulation (figs. 973, 974, 975). — The articular surfaces 

 concerned are the thyreoid articular surface on the side of the cricoid and the 

 articular surface on the inferior cornu of the thyreoid cartilage. The crico- 

 thyreoid articular capsule [capsula articularis cricothyreoidea] attached around 

 the margins of these surfaces and certain accessory bands serve to bind the carti- 

 lages together. 



The accessory bands, cerato-cricoid ligaments fall into three groups radiating from the 

 inferior cornu : the ligamenta ceratocricoidea posteriora upward and medialward to the superior 

 margin of the cricoid; the ligamenta ceratocricoidea lateralia downward at the side and back 

 of the capsule; the ligamentum ceratocricoideum anterius downward and forward. The 

 capsule possesses a synovial layer. 



A rotary movement about a transverse axis of the cricoid upon the thyreoid 

 or vice versa and a slight backward and forward gliding are permitted at this 

 joint. 



* Wrisberg: German anatomist. B. 1737, D. 1808. 



