The next thing to be done is to cut pieces of artificial cartilage, called "buffle," to fit the posterior articulating surface of the body of each vertebra, and each piece should be fastened to the vertebra to which it belongs by a small wire nail through its centre. The holes in each vertebra should be continued straight on through the false cartilage. Now cut a brass wire three times the length of the spinal column, double it, pull it straight, pass the two ends through the sacrum, and so on forward through all the vertebræ.
When the vertebræ have all been strung on the two wires and tightened up, it will be seen that the spinal column assumes a curve approximating very nearly to the natural one. Mark this curve with chalk on a table or a board.
Unstring the vertebræ from the wire. Then take a square rod of iron, a foot or so longer than the spinal column, and over which each of the vertebra will fit easily. Have the blacksmith flatten out one end into a sort of spear, so that it will fit snugly in the spinal canal of the sacrum (Fig. 73, c).
[a]Fig. 73.]—The Sacrum and Spinal Rod.
Drill a hole through the under surface of the sacrum, and on through the iron rod: Into this a brass pin is to be fitted at d. Bend the iron rod to correspond exactly with the curve previously marked with chalk on the board. Paint the rod black, and when it has dried place it again in the sacrum, drive in the brass pin, leaving enough of the end exposed to be seized with a pair of pliers and pulled out if desired. Now string the vertebræ over the rod and wires. If all fit properly they can then be unstrung preparatory to attaching the ribs to them.
[a]Fig. 74.]—The Attachment of the Ribs to a Vertebra.
Each rib should have a hole bored through its lower end at the middle, to come out on the inner surface (Fig. 74, b, b). Through these holes wires are to pass, as seen in the accompanying figure, and to these wires the sternum is presently to be attached.
Having arranged the ribs so that you know the place of each, take the first pair, and the first dorsal vertebra to which this pair attaches. Bore a hole with the drilling machine through the rib, beginning at the centre of the articular surface of the tubercle of the rib, directing the drill so that it will come out on the under side (Fig. 74, c, c); then drill a hole through the head of the rib (d, d). Now fit the rib to the vertebra, and with a small awl, a sharp-pointed wire, or drill, mark, through the holes already made, the points on the articular surface of the vertebra through which the holes should be drilled (a, a). Bore similar holes through the rib of the opposite side, then through the vertebra at the points marked, and the wire will pass through as in the figure.