THE HEAD AND NECK. 43 



facial artery on the outer surface of the masseter muscle, forming the masseteric 

 anastomosis. (3) The infraorbital anastomoses with the facial, below the orbit, 

 to form the infraorbital anastomosis. (4) The mental branch of the inferior 

 dental artery anastomoses with the inferior labial branch of the facial artery, 

 forming the mental anastomosis. (5) In the facial mid-line the corresponding 

 arteries of opposite sides of the face anastomose. At the aural, ocular, nasal, 

 and oral muco-cutaneous junctions capillary anastomosis takes place. (6) The 

 arterial anastomoses above referred to are attended by venous anastomoses. 

 The mental, infraorbital, and supraorbital may be compressed at their respective 

 exit foramina. The facial may be compressed on the mandible just in front of the 

 masseter muscle. (7) The important communication on the face is between the 

 ophthalmic and angular, by which route facial erysipelas may reach the meninges, 

 since the ophthalmic vein opens into the cavernous sinus of the dura mater. 



1 1 . Explain briefly the parotid gland. 



The gland is located in a depression having the following limitations : above, 

 the zygomatic arch ; below, the angle of the mandible and the masto-mandibular 

 line; behind, the external ear and sterno-mastoid muscle; in front, by the masseter 

 muscle ; deeply, it embraces the styloid processes and internal carotid artery. 

 The gland contains the seventh nerve and the auriculo-temporal branch of the 

 fifth nerve, both of which furnish it with nerve -filaments. It contains the external 

 carotid artery, which here breaks up into the temporal, internal maxillary, and 

 transverse facial branches ; these supply the gland with blood. It contains the 

 temporo-maxillary vein. The fascial covering of the gland is called the parotid 

 fascia. The gland is the largest of the salivary glands, and has an excretory 

 duct called Stenson's. 



12. Trace Stenson's duct. 



It crosses the masseter muscle in a line from the lobule of the ear to the 

 upper lip. It perforates the buccinator muscle, and opens into the vestibule of 

 the cavum oris opposite the second upper molar tooth. 



13. Where does the facial nerve escape from the cranium ? 



It escapes through the stylo-mastoid foramen, in the petrosa of the temporal 

 bone. On its escape it gives off the posterior auricular, the digastric, and stylo- 

 hyoid branches. It subsequently forms the pes anserinus, from which the 

 muscles of expression are innervated. The facial is a motor nerve. 



NOTE. Many a good dentist has been heard to tell his patient, "All this 

 toothache is caused by the facial nerve." The facial nerve makes you smile when 

 you hear such things ; it is the fifth nerve that is concerned in toothache. 



THE NECK. SUPERFICIAL DISSECTION. 



Locate on the cadaver : 



1. The lower border of the mandible and its angle. 



2. The mastoid process of the temporal bone, behind the ear. 



3. The sterno-clavicular articulation. Does it move? 



4. The interclavicular or suprasternal notch. How deep? 



5. The acromio-clavicular articulation. Does it move? 



6. An imaginary line from the angle of the jaw to the mastoid. 



7. The sterno-cleido-mastoid muscle and its double origin. 



8. The exact anterior border of sterno-cleido-mastoid. 



9. The exact posterior border of sterno-cleido-mastoid. 

 10. The cervical mid-line mento-sternal line. 



