REGIONAL CHANGES. 123 



quently the ninth vertebra has no half- facet below. The tenth has a nea/ly or quite 

 complete facet at its upper border, the eleventh has a complete one rather below 

 the top of the body, and the twelfth has a complete facet nearly half-way down. 

 At the ninth or tenth the facet begins to leave the body and to travel backward 

 onto the root of the pedicle. 



When the body is seen from above or below in certain parts of the thoracic 

 region the front curve is flattened on the left by the pressure of the aorta. This com- 

 pression usually is first seen at the top of the fifth thoracic, and is traceable down- 

 ward for a few vertebrce, sometimes as far as the lumbar region. The depression 

 gradually passes from the side to the front as it descends the spine. 



The Transverse Processes. — As shown by the table, the spread of the 

 transverse processes increases greatly at the junction of the cervical and the thoracic 

 regions, falls rapidly to the third thoracic, remains stationary to the tenth, falls to the 

 last thoracic, the narrowest point, and then gains at once, reaching the maximum at 

 the third lumbar. The anterior tubercles of the transverse processes of the cervical 

 region increase to the sixth, which is the tubey-de of Chassaignac, who taught that 

 the carotid artery can be compressed against it, the force being directed backward 

 and a little inward. The anterior limb of the transverse process of the seventh ver- 

 tebra is very short, and its tubercle is usually rudimentary. It is distinctly in series 

 with the slight elevation of the socket for the head of the first rib often seen on the 

 first thoracic vertebra. The piece of bone between the tubercles, forming the floor 

 of the gutter for the spinal nerve, is much longer and more anteriorly placed in the 

 seventh than in those above it. It is this piece connecting the two tubercles that is 

 the true costal eleme^it in the neck. The so-called anterior limb of the transverse 

 process with the tubercle on it is in line, not with the ribs but with the anterior 

 tubercle called \h^ processjis costarius. The articular facet on the transverse process 

 of the first thoracic is shallow, often convex, and faces a little downward. That of 

 the second, at which point the processes slant more backward, is concave and some- 

 what overhung above ; this is seen in the two or three following, after which the 

 facets grow smaller, more shallow, and look upward as well as forward. As the 

 eleventh rib has but a rudimentary tubercle and the twelfth none at all, there is no 

 facet on the transverse process of the last two thoracic vertebrae. The latter process 

 of the eleventh is small, and that of th last broken up into three tubercles, (i) the 

 superior or viammillary^ rising from the posterior surface ; (2) the accessory ox infe- 

 rior, pointing downward ; (3) the external, a knob, the smallest of the three. The 

 latter two represent the transverse process of the upper thoracic vertebrae. All three 

 tubercles are usually to be recognized on the eleventh thoracic, although the acces- 

 sory tubercle is usually not seen higher up. The knobs for muscular attachment on 

 the backs of the thoracic transverse processes are evidently in line with the mammil- 

 lary tubercles, rudiments of which are found in a large part of the thoracic region. 

 In the lumbar region they are found on the side of the superior articular processes, 

 growing smaller in the lower vertebrae, and being lost in the fifth. 



The lumbar transverse processes increase in length to the third, which is the 

 longest, unless it be equalled by the fifth. That if the fourth is peculiar in being 

 shorter and lighter than its n ighbors. It usually has a rather triangular outline, 

 owing to the lower border approaching the upper near the tip, and also arises farther 

 forward, — i.e., nearer the side of the pedicle than those above it. The fifth is much 

 heavier and arises from the side of the body as well as from the pedicle, so that its ante- 

 rior portion is evidently in series with the costal element developed in the sacrum, 

 described in connection with that bone. The process which, in accordance with gen- 

 eral usage, has been called the lumbar transverse process, is clearly in direct continua- 

 tion with the line of the ribs. This is particularly striking in certain cases in which it is 

 not easy to determine whether there is a thirteenth rib, or whether this process is to 

 be considered as free in the first lumbar. The accessory tubercle, which can be 

 inade out in the lumbar region, and is particularly large in the lower vertebrae, is 

 in line with the ends of the transverse processes of the thorax. Thus the so-called 

 lumbar transverse process represents at its root both a rib and the accessory and 

 transverse tubercles, and beyond its root a rib only. This is especially marked 

 in the broad process of the fifth lumbar, which springs from the side of the body 



