The Head and Neck. , 165 



lies above the soft palate, and receives the posterior aperture 

 of the nose. Its ventral and posterior laryngeal portion 

 (pars laryngea), not well-defined, contains the aperture of 

 the larynx, the aditus laryngis. 

 In the oral cavity: 



(a) The hard palate (palatum durum) forms the anterior portion 

 of the roof; its mucous membrane is thrown into a series of 

 transverse ridges. 



(b) The soft palate (palatum molle) is the thin, narrow, posterior, 

 membranous portion of the roof. It is very long in the rabbit, 

 extending from the bony palatine bridge backward to a 

 point above the laryngeal aperture, where it ends with a 

 concave free margin. 



(c) The nasopalatine ducts (dd. nasopalatini) open by minute 

 apertures immediately behind the small incisors. They 

 connect the anterior portion of the nasal cavity with the 

 mouth. 



(d) The tongue (lingua) projects upward and forward from its 

 basal attachments on the hyoid into the floor of the mouth. 

 Its connection with the latter is extended forward in the 

 middle line by a vertical membranous fold, the frenulum 

 linguae. Its dorsal surface is divided into a posterior 

 smooth and hard portion, and an anterior softer and rougher 

 portion, occupied by fine low elevations, the fungiform 

 papillae (papillae fungiformes). At the posterior end of the 

 smooth portion there are two small spherical elevations, the 

 vallate papillae (papillae vallatae), partly sunk in the mucous 

 membrane, and on either side an oval area, the papilla 

 foliata, the surface of which is marked by fine parallel ridges. 

 Both vallate and foliate papillae are occupied by microscopic 

 taste-buds. 



In the pharynx: 

 ' (a) The tonsil (tonsil-la) appears as a rounded mass of lymph 

 follicles lying on the anterior wall of a deep lateral depres- 

 sion, the tonsillar sinus (sinus tonsillaris). The vertical slit- 

 like aperture of the sinus is bounded by low anterior and 

 posterior folds, the glossopalatine and pharyngopalatine 

 arches. 



(b) The epiglottis, a triangular valve-like fold guarding the 

 entrance to the larynx, projects upward from the floor into 

 the pharyngeal cavity. 



(c) By removing the posterior portion of the soft palate the con- 

 nection of the nasopharynx with the nasal fossae will be 

 exposed; also on the lateral wall the small pharyngeal 

 aperture of the auditory tube (ostium pharyngeum tubae). 



10. Examination of the larynx. 



By cutting around the base of the tongue on the opposite side of the 



13 



