30 



verse process usually bounds a notch for the anterior division 

 of the fifth sacral nerve; or if it touches the inferior lateral 

 angle of the sacrum, it forms a fifth anterior sacral foramen. 

 The second vertebra has rudiments of transverse processes, 

 and two small eminences in line with the cornua, representing 

 the last traces of a neural arch. The third and fourth are 

 mere nodules, and represent vertebral bodies only. In adult 

 life the first piece is often separate, and the other three united. 

 All four may form one bone, which occurs oftener and earlier 

 in the male. 



To the edges of the coccyx are attached, in front, the coccy- 

 geus muscle; behind, the gluteus maximus; and between, these 

 the sacrosciatic ligaments. To the apex is attached the external 

 anal sphincter. 



This bone may consist of five vertebrae, or more rarely of 

 only three. 



The Vertebral Column as a Whole 



It is a central axis upon which other parts are arranged, 

 situated in the median line at the posterior part of the trunk; 

 above, it supports the head, laterally the ribs, and it rests 

 on the hip bones below. Its average length measured along 

 the curves is 28 inches in the male and 27 inches in the female; 

 persons seated in a row appear of about the same height. 



Viewed from the front, the column is formed of two pyra- 

 mids applied base to base at the junction of the last lumbar 

 with the sacrum. 



All three diameters of the vertebrae increase from the third 

 cervical to the last lumbar; vertical diameter, from f to li 

 inches (14 mm. to 29 mm.); sagittal, from f to If inches (14 

 mm. to 35 mm.); transverse (does not increase in dorsal region), 

 from i to 2^ inches (21 mm. to 55 mm.). 



.The column presents a slight lateral carve, convex to the 

 right in right-handed persons, convex to the left in left-handed 

 persons (Bichat). 



Viewed laterally there are four curves, alternately convex 

 and concave; the cervical, dorsal, lumbar, and pelvic; the 

 cervical extends from the odontoid to the second dorsal; the 

 dorsal is concave forward and ends at the twelfth dorsal; the 

 lumbar ends at the sacrovertebral angle, and the pelvic ends 

 at the tip of the coccyx. The dorsal and pelvic curves are 



