1 78 HEAD AND NECK 



which the auriculo -temporal nerve springs from the back of 

 the posterior division of the mandibular nerve. Follow the 

 auriculo-temporal nerve backwards and note how close it lies 

 to the medial face of the capsule of the temporo-mandibular 

 joint, before it enters the parotid region and ascends behind 

 the condyle of the mandible to the temporal region. Next 

 clean the upper part of the inferior alveolar nerve. Then turn 

 to the lingual nerve ; first clean its surface, then pull it forwards 

 and secure the chorda tympani which joins its posterior border, 

 after passing medial to the inferior alveolar nerve. Note that 

 the mandibular nerve divides into anterior and posterior parts. 

 The posterior division gives off the two roots of the auriculo- 

 temporal nerve and then divides into the inferior alveolar and 

 lingual branches, whilst the anterior division supplies all the 

 muscles of mastication, except the internal pterygoid and sends 

 the sensory buccinator nerve to the mucous membrane and 

 skin over the buccinator muscle. Now secure the nerve to 

 the internal pterygoid muscle which springs from the anterior 

 part of the trunk of the mandibular nerve, and, if possible, the 

 small nervus spinosus which passes backwards and laterally to 

 the foramen spinosum. 



Arterise Meningea Media et Tympanica et Eamus Menin- 

 geus Accessorius. The middle meningeal artery has already 

 been seen arising from the first part of the internal maxillary 

 artery. It passes upwards, medial to the external ptery- 

 goid muscle and lateral to the tensor veli palatini, and dis- 

 appears from view through the foramen spinosum, by which it 

 enters the cranial cavity (p. 118). It is usually embraced by 

 the two roots of the auriculo-temporal nerve. 



The accessory meningeal artery and the tympanic artery generally arise 

 from the middle meningeal. The accessory meningeal inclines forwards and 

 upwards, and enters the cranial cavity by passing through the foramen 

 ovale ; the tympanic runs upwards and backwards, and reaches the 

 tympanum by passing through the petro-tympanic fissure (O.T. Glaserian). 

 In the tympanic cavity it anastomoses with the stylo-mastoid branch of 

 the posterior auricular artery. 



Nervus Mandibularis. The mandibular branch of the tri- 

 geminal nerve arises, within the cranium, from the semilunar 

 (O.T. Gasserian) ganglion, and enters the infratemporal 

 region through the foramen ovale. It is composed of 

 sensory fibres, but it is accompanied through the foramen 

 by the small motor root of the trigeminal nerve ; and by the 

 union of the sensory and motor parts, immediately after 

 they gain the exterior of the cranium, a mixed nerve-trunk 

 results, which lies medial to the external pterygoid muscle and 

 lateral to the tensor veli palatini. 



Immediately after its exit from the skull the mandibular 



