io6 



APPLIED ANATOMY. 



bone, a cleft is left constituting harelip. If both processes fail to reach the premaxilla, 

 a double harelip is formed; the cleft may extend through the hard and the soft palate 



Frontonasal process 



Medial nasal process 



Nasal pit 



Lateral nasal process 



Lachrymonasal furrow 



Maxillary process 

 First visceral arch 



Mandibular process 

 First visceral furrow 

 Second visceral arch 

 Second visceral furrow 

 Third visceral arch 



FIG. 131. Frontal view of human foetus about four weeks old. (After His.) 



the cleft palate may alone be present as seen in Fig. 139(566 page 112). In operating for 

 harelip, the two sides of the cleft are freshened and sewed together, thus closing the cleft. 



FIG. 132. Paralysis of depressor labii inferioris from section of the lower filament of the facial nerve. (McDowd.) 



Paralysis of the lips is due to interference with the functions of the seventh nerve. 

 The muscles of the face and lip are supplied by the seventh or facial nerve. This is 

 frequently paralyzed, for owing to its tortuous passage through the temporal bone in 

 the canal of Fallopius it is injured in fractures of the base of the skull and becomes 



