Fig. 27 and 28. Tympanic Cavity and Surrounding Parts opened 



from behind. 



In Fig. 27, the outer wall 0/ the Mastoid Process, Antrum and Attic 

 have been removed, the Mastoid Cells gouged out so that only t/ie inner wall 

 of the Mastoid Process remains; Facial Nerve, Posterior and External Semi- 

 circular Canals and Lateral Sinus are still covered by bone. Facial Nerve and 

 Semicircular Canals (yellow) are represented as shewing through the bone. 



In Fig. 28, the skin incision has been extended downwards, the tip of 

 the Mastoid Process removed, the Digastric Muscle divided and the Attic more 

 freely exposed, the Facial Canal opened, the bony ivall of the Sinus removed 

 and the Sacciis Endolymphaticus exposed. 



The Posterior portion of the Tympanic Membrane, the Posterior and 

 Superior wall of the Bony External Auditory Canal luive been removed and 

 the skin which lines this portion slit open. The bar of bone behind the Stylo- 

 mastoid Foramen has been sawn through in order to expose the fugidar Bulb. 

 These figures give the relations which are of importance in radical operations. 



In cases of chronic suppuration and Cholesteomata of the Middle Ear, it is 

 important to expose all the cavities b\' removing their outer wall and bony septa 

 so that the inner wall of the Tympanic Cavit}-, Antrum and Mastoid becomes 

 continuous with the Inferior and Anterior Wall of the External Auditory Canal. 

 The bony canal for the Facial Nerve, the External Semicircular Canal and the 

 Stapes must be carefully avoided. The black area below the Incus represents 

 the Fenestra Rotunda. 



Fig. 28 shews the whole of the oblique part of the Lateral Sinus to its 

 termination in the Jugular Bulb. After reaching the Temporal Bone its direction 

 changes verticalh' downwards, embedded to varying depths in the inner wall of 

 the Mastoid Process, thence its course is at first horizontalh* inwards (occasionally 

 with a sharp upward curve), then directly downwards to pass through the Jugular 

 Foramen and form the Jugular Bulb. Suppurative Thrombo - phlebitis usually 

 affects this last vertical portion, in many such cases the Sinus must be opened 

 throughout its whole length. 



Many ways may be employed to expose the Jugular Bulb: Gruxert 

 removes the tip of the Mastoid Process and proceeds towards the Jugular Foramen 

 at the base of the skull where he divides the bone encircling" it. As shewn in 

 the figure the Facial Nerve is in the way. Panse therefore recommends that the 

 nerve be freed and drawn forward. If the Transverse Process of the Atlas is in 

 th3 way it should be carefuUv removed, avoiding any injury to the Vertebral 

 Arter)^ Owing to anatomical variations, this may be impossible so that CtRUNERT's 

 method (as practiced by PiFFL), of removing the floor of the Auditory Meatus and 

 T\'mpanic Ring, under which the Jugular Bulb lies, may be necessary. (Cf. Fig. 17.) 



By this method the Facial Nerve lies behind the field of operation; the 

 structure to be avoided in front is the Internal Carotid Arter)'. Will ligature of 

 the Internal Jugular Vein in Septic Thrombophlebitis prevent the spread of infection ? 



This question demands a consideration of the many Venous Channels 

 which open into the Lateral Sinus (Superior Petrosal Sinus, Figs. 15, 16, 20), Mastoid 

 Emissary' Vein (Figs. 20 and 28), Posterior Condylar Emissary Vein (Fig. 20), 

 ilarginal Sinus (Fig. 15), Inferior Petrosal Sinus (Fig. 15), Anterior Condylar 

 Vein which accompanies the Hypoglossal Nerve and passes to the Jugular Bulb 

 from the Vertebral Plexus. The figure shews the close proximit}' of Facial and 

 Spinal Accessory Nerves so that in cases of Facial Parah'sis the Surgeon may 

 be tempted to suture the central portion of the Spinal Accessor}- to the Peripheral 

 portion of the Facial Nerve. 



