THE TONGUE. 951] 
the anterior palatine arches. The foramen cecum is the remains of a tubular 
down-growth formed early in embryonic life, in the region of the dorsum of the 
tongue, from which the isthmus of the thyroid gland is developed (see page 36). 
The posterior or pharyngeal portion of the dorsum lingue (Fig. 6: 39), nearly 
vertical in direction, forms the greater portion of the anterior wall of the oral 
pharynx (Fig. 641). Its surface is free from evident papill, but is thickly studded 
with rounded projections, each presenting, as a rule, a little pit, visible to the 
Middle turbinated bone 
Superior meatus of nose 
Middle meatus of nose 
Inferior meatus \ 
of nose \ as 
\ 
Sphenoidal sinus 
/ 
/ Inferior turbinated bone 
/ / 
Posterior edge of nasal septum 
Orifice of Eustachian 
Part of the 
— pharyngeal tonsil 
Lateral recess of 
pharynx 
Levator cushion 
___ Salpingo- 
pharyngeal fold 
Glands in soft 
palate 
Anterior 
palatine arch 
Supratonsillar 
fossa 
~ Plica triangularis 
Tonsil 
~ Posterior palatine 
arch 
Epiglottis 
Aryteno- 
epiglottic fold 
Genio-glossus 
Genio-hyoid 
: - Cricoid cartilage 
Lymphoid follicle 
/ 
Hyoid bone 
Fic. 639.—SacirraL SecTION THROUGH Mourn, Tonauk, LAryNx, PHARYNX, AND NasaL CAVITY. 
The section was slightly oblique, and the posterior edge of the nasal septum has been preserved. 
The specimen is viewed slightly from below, hence the apparently low position of the inferior 
turbinated bone. 
naked eye, at its centre; the great majority of these are lymphoid follicles (folliculi 
tonsillares linguales, Fig. 644, C) similar to those found in the tonsils; some few 
are said to be mucous glands; all are covered by a smooth mucous membrane, 
and they combine to give to this region a characteristic nodular appearance. 
The mucous membrane of this portion of the tongue is separated from the 
muscular substance by a submucous layer in which the lymphoid follicles and 
the mucous glands lhe embedded (Fig. 639). At the sides it is continuous 
with that covering the tonsils and the side wall of the pharynx; whilst behind 
it is reflected on to the front of the epiglottis, forming in the middle line a 
