io4 SURGICAL APPLIED ANATOMY. [Chap, vn 



maxilla is moved forwards, as in protruding the chin. In 

 the latter movement, the increase intheantero-posterior 

 direction is equal to about three-eighths of an inch. 

 It is diminished when the head is flexed. When the 

 mouth is widely opened the space is diminished below, 

 while it is increased above by the gliding forwards of 

 the condyle. These facts should be borne in mind 

 in operating upon and in exploring the parotid space. 

 It will be found also that in inflammation of the 

 parotid much pain is produced by all those move- 

 ments that tend to narrow the space occupied by the 

 gland. The obliquity of the ramus of the jaw in 

 infancy and old age causes the lower part of the space 

 to be, in the former instance relatively, and in the 

 latter instance actually, larger than it is in the adult. 

 The gland is closely invested by a fascia derived 

 from the cervical fascia. The superficial layer of the 

 parotid fascia is very dense, is continuous behind with 

 the fibrous sheath of the sterno-mastoid, and in front 

 with that of the masseter. Above it is attached to 

 the zygoma, while below it joins the deep layer. The 

 deep layer is slender, is attached to the styloid process, 

 forms the stylo-maxillary ligament, and is connected 

 with the sheaths of the pterygoid muscles and the 

 pterygoid process. The gland is, therefore, encased 

 in a distinct sac of fascia, which is entirely closed 

 below, but is quite open above. Between the anterior 

 edge of the styloid process and the posterior border 

 of the external pterygoid muscle there is a gap in 

 the fascia, through which the parotid space communi- 

 cates with the connective tissue about the pharynx. 

 It is well known that in post-pharyrgeal abscesses 

 there is very usually a parotid swelling, and in several 

 instances the pus, or at least some portion of it, has 

 been evacuated in the parotid region. In these cases 

 the matter most probably extends from the pharyngeal 

 to the parotid region, through the gap just described. 



