PAROTID REGION . 165 



and the transverse facial and middle temporal offsets of the 

 superficial temporal will also be displayed. 



When the remains of the deeper part of the gland have been 

 removed, the styloid process with the origin of the stylo-hyoid 

 muscle, and the posterior belly of the digastric will be exposed ; 

 and the internal jugular vein and the internal and external 

 carotid arteries will be seen disappearing under cover of the 

 digastric. If the occipital artery lies at its lower level, it also 

 will be noted as it runs upwards and backwards, along the lower 

 border of the digastric, crossing superficial to the two large 

 vessels, and to the accessory nerve, which emerges from under 

 cover of the digastric and passes downwards and backwards 

 across the internal jugular vein. 



The dissector should now obtain a gland which has been 

 removed uninjured from the parotid space, or a cast of a 

 gland, and proceed to study the relations of the upper end 

 and the postero-medial and antero-medial surfaces. 



The upper surface presents a deep concavity which is 

 usually separable into a larger lateral part which lies in 

 contact with the cartilaginous part of the external meatus, 

 and a smaller medial part which touches the bony wall of the 

 meatus (Fig. 61). The anterior boundary of the upper 

 end forms a sharp ridge, which lies in the narrow interval 

 between the capsule of the mandibular articulation and the 

 front of the external meatus. 



The postero-medial surface is marked by a series of depres- 

 sions which correspond with the structures in the postero- 

 medial boundary of the parotid space. Above is a shallow 

 depression corresponding with the anterior border of the 

 mastoid process, and, below the latter, a groove caused by the 

 anterior border of the sterno-mastoid. More medially is a 

 shallow depression due to the posterior belly of the digastric 

 and the stylo-hyoid, and, still more medially and at a higher 

 level, a sulcus which corresponds with the position of the 

 styloid process. Below the level of the digastric groove the 

 postero-medial surface covers portions of the internal jugular 

 vein and the internal and external carotid arteries (Fig. 61). 

 The communication to the external jugular vein, the posterior 

 facial vein, and the cervical branch of the facial nerve emerge 

 from that part of the surface. Immediately above the digastric 

 groove, close to the medial border, the external carotid artery 

 enters the gland ; and, directly lateral to the upper end of the 

 groove for the styloid process, the facial nerve passes into the 

 gland substance (Fig. 62). The dissector should note that 



in 11 b 



