Fig- 3^' Side View of Face, deep layer. 



The brandies of the Facial Nerve have been cut off but its communications 

 with the Auriculo-Temporal Nerve have been exposed to view: the Zygoma has 

 been sawn through and removed together with the upper part of the Masseter 

 Muscle, (in a similar manner, the Coronoid Process with the attached Temporal 

 Muscle). All the chief branches of the 2nd a7id jrd divisions of tJie Vth Cranial 

 Nerve and the branches of the Internal Maxillary Artery are exhibited. 



Under cover of tlie Coronoid Process of the Lower Jaw and the Temporal 

 Muscle attached to it, the structures of the Zygomatic Fossa are covered with fat. 

 After the removal of this fat the External Pterygoid Muscle is seen extending 

 from the Pterygoid Process to the Condyle of the Lower Jaw. The relation of 

 the Internal Maxillary Arter}' (terminal branch of External Carotid Artery) to 

 this muscle varies as it runs, either superficial or deep to the muscle, to gain the 

 Spheno-Maxillary Fossa. This vessel gives off the Middle Meningeal Arter}^ which 

 runs upwards to the P'oramen Spinosum and the Inferior Dental Artery which 

 enters tlie Inferior Dental Foramen. After removal of the External Pterygoid 

 Muscle the 3rd or Inferior Maxillar3'-Division of the Vth Nerve is visible. 



After passing through the Foramen Ovale this breaks up into numerous 

 diverging branches. The Auriculo-Temporal Nerve passing backwards emerges 

 behind the Temporo-Maxillary Articulation and supplies the skin of the temporal 

 region witli common sensibilit}', this nerve generally forms a loop through which 

 the Middle Meningeal Artery passes. The other branches are partly motor and 

 supply the Muscles of IMastication (Internal and External Pterygoids, Masseter 

 and Temporal), and partly sensory, long Buccal to the skin and Mucous Membrane 

 of the Cheek. The two largest branches, Inferior Dental and Lingual, pass down- 

 wards on the Internal Pterj-goid Muscle; the former, the larger nerve, is the 

 more posterior. 



In the Spheno-Maxillary Fossa but situated anteriorh^, is the posterior 

 surface of the Superior Maxilla. The Infra-orbital Artery, a branch of the Internal 

 MaxiUary Artery, enters the Infra-orbital Canal, while close above this vessel lies 

 the 2nd division of the Vth Nerve which in its course from the Foramen Rotundum 

 to enter the Infra-orbital Canal inclines outward. In its short course it gives 

 off the Spheno-Palatine Nerves to the Spheno-Palatine Ganglion (Meckel's, 

 cf. Fig. 44) and through the Pterygo-Maxillary Fossa the Zygomatic, Superior 

 Dental and Sphenopalatine Nerves. 



Operations in this region — for removal of tumours, resection of the 2nd 

 or 3rd divisions of the Vth Nerve for Acute Neuralgia — are rendered difficult 

 by the diffuse Venous Plexus (Pterygoid Plexus) which replaces the Venae Comites 

 of the Internal MaxiUar)' Artery. This plexus which has been removed in the 

 dissection, extends from the Infra-orbital Canal and Spheno-Maxillary Fissure 

 between the Pterj'goid Muscles as far as the Temporo-Mandibular Joint. 



