

Kyphosis. 



Spinal Curvature 207 



common ligament, just as the posterior occipito-atloid ligament repre- 

 sents the ligamentum subflavum. The posterior ligament is attached 

 above to the back of the foramen magnum, and is pierced by the verte- 

 bral arteries and the suboccipital nerves. In front it is 

 intimately connected with the dura mater as it descends 

 into the spinal canal. 



The lateral ligaments pass between the transverse 

 process of the atlas and jugular eminence of the occipi- 

 tal bone. 



The occiput is connected with the axis by an upward 

 prolongation of the posterior common ligament, which 

 blends at the front of the foramen magnum with the 

 cranial dura mater. 



Beneath it are two cheek ligaments, which pass from 

 the tip of the odontoid process to the inner sides of the 

 occipital condyles, and a third slip which runs up to the 

 front of the foramen magnum. 



When the weight of the head and the upper part of 

 the body is greater than the spinal column is able to 

 support it bends forwards in an exaggeration of the 

 normal curve of the dorsal region, just as the stalk, of 

 corn yields when the ear of wheat is large and full. In 

 the human subject the bending may be due to a deficiency of earthy 

 matter in the bony segments, as happens in the rickety child, or to a 

 settling down of the vertebrae and the intervening discs 

 from long-continued pressure, as in the rheumatic or old 

 and worn-out labourer. The curvature is dignified by 

 the name of kyphosis (KV^OS, bowed forwards}. 



Iiordosis, or saddle-back (XopSoy, curved], is the 

 opposite condition, the trunk being thrown backwards 

 by exaggeration of the normal lumbar curve, the con- 

 cavity of which looks backwards. It is usually a com- 

 pensatory curve which the subject instinctively acquires 

 in order to keep the centre of gravity from being ad- 

 vanced too far, and unstable equilibrium being thereby 

 produced. Thus, it is found in pregnant women, who 

 are compelled to throw the shoulders backwards in 

 walking ; and, to a less degree, in the very fat man. It 

 is still better marked when caries of the high dorsal ver- 

 tebras has allowed the head and shoulders to fall for- 

 ward, and also when, from congenital displacement, the 

 heads of the femora are behind their normal position, as 

 figured on page 472. 



Lateral curvature. The commonest variety is that in which the 

 right shoulder is raised, the convexity of the lateral dorsal curve being 



1 These and similar figures are from Erichsen's Surgery. 



Lordosis. 1 



