SPINE. 



procers are broad and thick, and the procefs itfelf is ftrong 

 and prominent, projefting confiderably beyond tlioleof the 

 fucceeding bones. It is rough belnw, and ends behind 

 either in an expanded knob, or in a bifurcated extremity. 

 On each fide of the tooth-hke procefs there is a large circu- 

 lar and nearly horizontal plane, for articulation with the 

 atlas. The inferior articular procefles are fimilar to thofe of 

 the other cervical vertebrse : they are oblique, placed behind 

 the tranfverfe procefles, and have their articular faces turned 

 forwards. The fuperior notches for the nerves are behind 

 the fuperior planes ; while the inferior are in front of 

 the correfponding articular procefles. The tranfverfe pro- 

 cefs is fmall, and perforated for the vertebral artery by 

 a foramen, which is diredled obhquely upwards and 

 outwards 



The axis b united to the head, the atlas, and the third ver- 

 tebra of the neck. 



To its tranfverfe procefs, the fplenius capitis, levator fca- 

 pulse, fcalenus, tranfverfus cervicis, longus colli, and inter- 

 tranfverfi anterior and poflerior, are affixed : to the fpinous 

 procefs, the reftus capitis poiterior major, the obUquus in- 

 ferior, the ferai-fpinalis cervicis, the mterfpinalis, and multi- 

 fidusfpinx. 



The Jive loiver cervical Veriebne. — The body is very fmall, 

 in comparifon to the procefles and the ring ; it is flattened 

 in front, and elongated tranfverfely, fo that it is on a level 

 nearly with tlic tranfverfe procefles, initead of projefting 

 into a bony column in front of them, as it does in the other 

 regions of the fpine. It is rather thicker before than be- 

 hind : its fuperior furface is concave from fide to fide, rifing 

 up laterally into two thin ridges, and rather floping off in 

 front : the inferior prefents juft the oppofite conformation, 

 fo as to fit it to be received into the hollow of the vertebra 

 below. We may notice, in front, a middle furface, cor- 

 refponding to the anterior vertebral ligament, and two la- 

 teral ones, adapted to the longi colli. A fmall articu- 

 lar furface is obfervable on each fide of the lower edge of 

 the body of the feventh, contributing to the cavity in which 

 the head of the firft rib is lodged. The ring for the 

 fpinal marrow is large and triangular, with the angles 

 rounded. The fpinous procefles are prifmatic, horizontal, 

 and either bifurcated at the end, or flattened and marked 

 with a groove. They vary confiderably in their direftion, 

 degree of bifurcation. &c. Three of the four vcrtebrx im- 

 mediately fucceeding the axis appear very fmall in compa- 

 rifon to its fpinous procefs ; but the fpine of the feventh is 

 Large and prominent. The notches for the lateral foramina 

 are placed in front of the articular procefles ; and the fu- 

 perior and inferior ones differ very little in depth. The ar- 

 ticular procefles are oval in their figure, and diretted 

 obliquely : tlie fuperior backwards and upwards, the infe- 

 rior forwards and downwards. The tranlvcrfe procefles in- 

 creafe in fize from the axis ; there is a deep channel in the 

 fuperior furface of each, lodging the anterior branch of the 

 correfponding cervical nerve ; hence the extremities are bi- 

 furcated. Each is perforated at its bafe by a round hole for 

 the vertebral artery ; which has been obfcrved fometimes to 

 be abfcnt in the feventh. 



The feventh cervical approaches in all refpefts very nearly 

 to the charafters of the dorfal vertebn. 



The mufcles attached to the cervical vertebra; are the in- 

 terfpinales ; the intertranfverfi anteriores and piilleriores ; 

 the reftus amicus major ; longus colli ; fcaleni, anterior 

 medius and poiterior ; cervicalis defcendens ; tranfverfalis 

 colli ; facrolumbalis ; ferratus podicus fuperior ; rliom- 

 boidens minor ; trapezius j fplenius capitis ; and part of 

 the rhomboideuis major. 



The Dorfal Vertehrt. — Their number depends on that of 

 the ribs : they are very feldom eleven ; more frequently 

 thirteen ; in which latter caie there are generally only four 

 lumbar vertebrx. Their chief charaftenftics arife from the 

 articulation of the ribs to this part of the column. 



The body projefts in front, when compared to the ver- 

 tebra of the neck : it is thick behind, and narrower in 

 front. The upper and under furfaces are plane. It is con 

 vex in front, a little concave behind. It ib longer, thicker, 

 larger in all refpet\s, and more cylindrical, in proportion aa 

 we defcend. The body of the firll, or even of the fecond 

 alfo, is flattened in front, like thofe of the cervical ; but the 

 third, fourth, fifth, and fixtli, have the cordiform (hape, 

 being broad behind, and narrow in front ; the feventh, 

 eighth, and the reft, are more and more cylindrical. Gene- 

 rally, the third and fourth are the fmallelt of all. At its 

 lateral and poiterior part there is a fmall articular furface 

 above and below, of which the upper is the largelt. Thefe 

 cartilaginous furfaces form, with the correfponding ones of 

 the neighbouring vertebrje, and the intermediate fibro-carti- 

 lages, the articular concavities, which lodge the heads of the 

 ribs. Sometimes the firft dorfal vertebra ha? an entire arti- 

 cular concavity at its upper edge, and a half cavity below : 

 or the upper may be a half cavity alfo, the articulation 

 being completed by the lower margin of the feventh cervi- 

 cal. In the eleventh and twelfth there is a fingle cavity- 

 only, placed either at the upper edge or towards the middle 

 of the bone, and receiving by itfelf the head of the corre- 

 fponding rib. The ring is fmall and circular. The plates 

 are broad, thicker, and more perpendicular than in the 

 neck ; and they give origin to a very long fpinous procefs, 

 which is prifmatic, pyramidal, broad at the bafis, and grow- 

 ing narrower at the oppofite extremity, which i^ pointed, 

 and dircdled obliquely backwards and downwards. The 

 fpinous procefs of the firft dorfal vertebra is thick, extend- 

 ed nearly horizontally, and ends in a flattened tubercle. 

 The fecond, and particularly the third, is more llanling ; 

 the upper margin more acute ; and the extremity longer and 

 more pointed. Thefe characters become more flrongly 

 marked in the fourth to the feventh or eighth : they are 

 very long, and pointed, the fuperior edge is very acute, and 

 the inferior furface is nearly flat ; they flope fo much, that 

 they lie one over the other, in clofe contait, while thofe of 

 the three upper and four lower Hand quite apart. The 

 effeft which this arrangement mull have in limiting the pof- 

 terior inflexion of the column is very obvious. In the four 

 loweft dorfal vertebrae, the depth of the fpinous procefles, 

 from above downwards, is increafed ; they are extended 

 more horizontally, and the length ot their points is dimi- 

 nifhcd. The fpnious procefles of the dorfal vertebrx are 

 feldom all arranged in the fame perpendicular line : one may- 

 deviate to the right, another to the left, &c. The articu- 

 lar procefles are perpendicular, the fuperior being direded 

 backwards, tlie inferior forwai-ds, excepting the inferiof ones 

 of the twelfth, which are turned outwards, to be adapted 

 to the fuperior procefles of the firll lumbar vertebra. 



The tranfverfe procefles are very thick, and confiderably 

 inclined backwards : this, together with the concavity of 

 the column in the back, enlarges the fpace for the reception 

 of the lungs. When the fpine is viewed laterally, the tranf- 

 verfe prc)cefl"es of the dorfjil are confiderably behind the line 

 of thofe of the cervical or lumbar regions. Each of them 

 has a fmall plane, or very gently concave, furface, on the 

 anterior part of its extremity, by which it is articulated to 

 the tubercle of the correfponding nb. Thefe furfaces are 

 direded upwards in the fuperior vertebrx, downwards ia 

 the inferior. The tranfverle procefles dccreafe confiderably 



from 



