138 APPENDIX 



mid-dorsal line with the blade- width transverse to the long axis of the neck. The point is 

 entered just behind occiput and thrust through occipito-atloid space until the edges feel the 

 side-limits of the space ; the neuraxis is thus completely severed. The place of transection 

 lies about 4 mm. behind the point of the calamus scriptorius, and passes through the 

 posterior part of the pyramidal decussation. The width of the knife-blade should not 

 exceed 12 mm. or the blade may jamb in the vertebral canal. The blade-edge is then, with- 

 out withdrawing the knife, pressed against the left occipito-atloid joint while with the left 

 hand the head is turned toward the preparation's right side. This opens the left occipito- 

 atloid joint, and the knife is swept laterally as well as downward and forward through it, 

 an assistant, if available, holding the neck-string backward to steady the preparation as the 

 cut is made. The left hand still retaining hold of the head, the transversely-cut spinal cord 

 is in full view, and twisting the head now somewhat to the preparation's right the knife-edge 

 is passed through the right occipito-atloid joint and forward and downward through what 

 remains of the right side of the neck. The head thus severed is pithed and thrown away. 



(6) Respiratory movement ceased of course when the knife transected the neuraxis. 

 The haemorrhage is extremely slight. The carcase is now taken to the student's operation 

 table, where the ends of the neck-string ligature are looped over a cross-piece on a vertical 

 standard set ready for it, and arranged so that the neck-stump is supported about 15 cm. 

 above the rest of the carcase lying on the table. The short flexible tubing from the nozzle 

 of the ' blower ' (ventilation pump) in the table-top is then joined to the tracheal cannula. 

 The tie-clip clamp on the bit of rubber tube on the side-branch of tracheal cannula is 

 adjusted to give a suitable degree of inflation under the strokes of the blower. Experience 

 shows that although delay in attaching the ventilation pump should not exceed 2-3 min., 

 the urgency is not greater than that. Spontaneous occurrence of reflexes, e. g. scratch reflex, 

 usually gives warning that ventilation is insufiicient, or asphyxial excitation impending. 



(7) It is well to wait 3'-6' before lowering the neck-stump down fully to the level of 

 the rest of the carcase on the table-top. If there is any oozing haemorrhage from the verte- 

 bral canal it can be controlled and arrested by keeping the neck-stump raised for longer or 

 by raising it still higher, or, if necessary, by tying a string tightly round the projecting 

 condyles of atlas. Occasionally there may be smart arterial bleeding from one or other 

 side of the atlas ; this is due to one or other vertebral artery having escaped compression by 

 the string ligature passed behind the wings of atlas at the time of operation. It can be 

 easily stopped at once by compressing between the finger and thumb of left hand laterally 

 the muscular stump of the neck close behind - the wings of atlas and, with fine forceps in 

 the right hand, stuffing the exposed foramen in arch of atlas, through which pass the verte- 

 bral artery and 1st cervical nerve, with a minute pledget of cotton wool. 



(8) Before lowering the preparation to the horizontal position for use by the student 

 the truncated neck is secured in a holder so as to enable the student to place it readily in 

 any pose suitable for his exercise and supported during his manipulations. The holder 

 consists of a small chemical retort clamp modified (text-fig. 44) by provision of a pair of 

 small screws set in the lip of each blade, enabling the blade to grip securely the margin of 

 neural arch and body respectively of the atlas, which already lie exposed and projecting 

 from the neck-stump. The clamp should not be tightened so much as to compress the 

 spinal cord ; such pressure provokes, and may continue to provoke for a long time, reflex 

 movements, e. g. scratch reflex, &c., recurrence of which will disturb the student's work. 



