DEVELOPMENT OF THE PHARYNX AND NECK. 



43 



of the inner, by a process of budding, arises the submaxillary 

 gland ; the sublingual arises by a number of buds from the outer 

 groove (Fig. 32). The parotid gland springs as a bud from the 

 angle between the mandibular and maxillary processes. It is 

 probably hypoblastic in nature, but it may arise from the epiblast 

 of the stomodaeum, for as yet its exact origin has not been deter- 

 mined. It grows backwards in the connective tissue over the 

 masseter, and at birth is comparatively superficial in position, but 

 as the mandible and external auditory process grow, it sinks 

 inwards to surround the styloid process, pushing the deep cervical 

 fascia beneath it. In this way the stylo-maxillary ligament is 

 formed from the fascia pushed in front of it. Its nerve is derived 

 from the 3rd division of the Fifth (auriculo-temporal). 



Seessel's Pocket. — In the middle line of the roof of the 

 pharynx (Fig. 33), just under the basi-occipital, there is a 

 if 



's pocket 

 Eustach. tube 

 lateral recess of pharynx 

 soft palate (max. proc.) 

 plica semilunaris 

 tonsil 

 ost. pillar 



epiglottis 



duct 



position 1st cleft- 

 remnant of thyro-glosr 

 hyoid- 

 2nd clef if-/ 1 

 3rd cleft-/ 

 4th cleft' 

 median lobe of thyroid' 



pyri form fossa 

 oesophagus 

 ventricle of larynx 



Fig. 33.— Showing the position of the Visceral Clefts in the Adult. 



depression or recess of mucous membrane which gets this name. 

 It is of no practical importance, and its embryological significance 

 is doubtful. Lymphoid tissue is developed in its walls and in 

 the mucous membrane round it. It may be a remnant of the 

 pharyngeal opening of the notochord (see page 146). It is 

 developed behind the oral plate. 



