THE NECK. 



169 



AFFECTIONS OF THE NECK. 



Cervical Cysts and Fistulae. The neck is the seat of some very peculiar 

 cystic tumors and fistulae which are connected with developmental defects. They 



arch 



FIG. 188. Foetus, 25th day (after His). Showing branchial (visceral) arches and clefts or furrows. 



are either lateral or median in location. The lateral originate from the visceral 

 (branchial) clefts, while the median are connected with the thyroglossal duct. The 

 visceral clefts are depressions between the visceral arches. These arches, five in 

 number, spring forward from each side of the embryo to form the neck region. 

 Sometimes these arches are called branchial arches from the fact of their going to 

 form the branchiae or gills of fishes and 

 some of the other lower orders of animals. 



The first visceral arch divides into 

 two parts, a maxillary part forming the 

 upper jaw and a mandibular part form- 

 ing the lower jaw. Defects in the max- 

 illary arch producing harelip and cleft 

 palate have already been described. 

 Two of the ear bones, the incus and 

 malleus, are also formed by the mandib- 

 ular portion of the first visceral arch. 



The second visceral arch forms the 

 stapes, the styloid process, the stylo- 

 hyoid ligament, and the lesser horn of 

 the hyoid bone. 



The third visceral arch becomes the 

 body and greater horn of the hyoid bone. 



The fourth andyf/7A visceral arches 

 blend and form the soft structures of the 

 side of the neck. 



The first visceral cleft, called the 

 hyomandibular cleft from its being be- 

 tween the hyoid bone and the mandible, 

 forms the middle ear and Eustachian 

 tubes from its inner portion and the external auditory meatus from its outer portion. 

 The membrana tympani is the remains of the membrane which stretched across from 

 one arch to the other. Cervical fistulae are formed by the persistence of a visceral 

 cleft. As the first visceral cleft persists normally in the structures already named, it 



FIG. 189. Points of opening of sinuses originating 

 from the thyroglossal duct and branchial clefts. (Modi- 

 fied from Sutton.) 



