314 ANATOMY OF THE RABBIT 



(d) The corniculate cartilages (cartilagines corniculatae) are 

 minute, slender, curved bodies composed of very flexible 

 elastic cartilac^e and borne on the apices or anterior ex- 

 tremities of the arytenoid cartilages. Each projects craniad 

 and lies in the dorsal end of the fold of mucous membrane 

 extending to the edge of the epiglottis and forming the 

 margin of the opening from the pharynx, the aditus laryngis. 



(e) The epiglottic cartilage (cartilago epiglottica) is a thin, 

 very flexible, curved plate of elastic cartilage covered only 

 by mucous membrane. It projects upward into the cavity 

 of the pharynx just in front of the aditus laryngis and is 

 attached ventrally to the internal surface of the thyreoid 

 cartilage. At the base of its posterior surface appears a 

 pair of small but prominent projections, the hamuli. 



(/) The vocal folds (plicae vocales), which are rudimentary in 

 the rabbit, may be seen as vertical folds of the internal 

 surface of the larynx, especially prominent when the thyreoid 

 cartilage is bent downward on the cricoid. Each fold is 

 attached at one end to the thyreoid, at the other end to an 

 arytenoid cartilage, and forms the posterior boundary of a 

 shallow pouch, thelaryngeal ventricle (ventriculus laryngis.) 



In the rabbit the two laryngeal ventricles unite in a shallow median 

 ventral depression which extends to between the hamuli epiglottici. 



In addition to the cricothyreoidei, the laryngeal cartilages are 

 connected by several small muscles, including the cricoarytenoidei 

 posterior and lateralis, the thyreoarytenoideus and the ar3'tenoideus 

 transversus, the last named being an unpaired muscle connecting the 

 arytenoid cartilages. These muscles acting together in various ways 

 modify the shape of the laryngeal cavity and the degree of tension and 

 of approximation of the vocal folds. 



11. The eye and related structures of the orbital cavity. 



The eyeball should be carefully separated from the bony orbital 

 rim. The first portion of the nasolacrimal duct (d. nasolacrimalis), 

 passing from its aperture, which may be observed in the anterior 

 part of the medial surface of the lower eyelid, to the lacrimal bone, 

 will be divided. The supraorbital process of the frontal bone may 

 advantageously be broken away. The muscles and glands of the 

 orbit may be made out as follows: 



