THE PHARYNX. 



1601 



and perhaps others, reach it beneath the mucous membrane. Under ordinary cir- 

 cumstances the tonsil is not very vascular, but receives a large quantity of blood 

 when inflamed. There is a venous plexus communicating with the veins of the 

 pharynx. The lymphatics probably communicate both with those of the dorsum 

 of the tongue and with the glands near the angle of the jaw. 



Nerves. The nervous supply is from the fifth and the glosso-pharyngeal. 

 (The relations of the tonsils are given with those of the pharynx, page 1602.) 

 The pharyngeal tonsil (Fig. 1353), sometimes called the third tonsil, is a 

 median mass of adenoid tissue in the postero-superior wall of the pharynx, which 

 reaches its greatest development in early childhood, generally dwindling after the 

 twelfth year. When well developed, it lies below the occipital and the basi-sphenoid, 

 nearly filling the space from the nasal septum to the back of the pharynx and almost 

 touching on either side the folds made by the tubal cartilages. Its thickness in the 

 median line is nearly i cm. Thus without being hypertrophied it nearly fills the naso- 

 pharynx. The pharyngeal tonsil is a lobulated organ, the swellings being often regu- 



Foramen caecum 



FIG. 1357. 



Crista gall 



Cartilage of septum 

 Vomer 



Permanent incisor 



Tongue 



Frenum of tongue 



Genio-hyoid 



Mylo-hyoid 



Hyoid bone 

 Thyroid cartilage! 



Pituitary body 



Cranio-pharyngeal canal 



Pharyngeal tonsil 

 Occipital bone 

 Pharyngeal tonsil 



Anterior arch of atlas 



.Odontoid process 

 .Uvula 



Epiglottis 



Third cervical vertebra 



Ventricle of larynx 



&\ 



-Cricoid cartilage 

 Anterior portion of mesial sagittal section of child's head, probably of about three years. Reduced one-fourth. 



larly arranged around a central depression ; consequently it presents many pockets. 

 The central one, which varies widely, is often improperly called the bursa pharyngea. 

 It has absolutely nothing to do with the canal from the mouth to the sella turcica, 

 through which a process of the oral tissue passes in early foetal life to the pituitary 

 body (Fig. 1357), being decidedly behind that passage. Neither is it the true bursa 

 pharyngea, since this term is more properly applied to a structure of uncommon 

 occurrence, namely, a still more posterior pocket in the mucous membrane leading 

 from the roof of the pharynx, just behind its tonsil, into a small recess not over 1.5 

 cm. in length, on the under side of the basilar process. 



Relations of the Pharynx. The structures behind the posterior wall have 

 been mentioned (page 1596). The tip of the normal uvula hangs on a level near the 

 lower part of the axis or the top of the third cervical vertebra. The tip of the epi- 

 glottis is usually opposite the lower part of the third. The second and third cervical 

 vertebrae are those behind that part of the pharynx seen through the open mouth. 

 The pharynx ends at about the top of the seventh cervical vertebra. The lateral wall 

 of the pharynx is very narrow, except in the region of the tonsils, where it reaches for- 

 ward to the anterior pillar of the fauces. From the top of the thyroid downward it 



