154 ARTICULATION AND SUPPORT 



ligament*. This arrangement bestows on quadrupeds the 

 power of using their jaws for seizing what is before them ; 

 of elevating them to reach what may be above the head, 

 although the body be placed horizontally; and of touching 

 the ground with the mouth, by depressing the head and neck 

 as low as the feet. In several animals there is some dis- 

 tance between the foramen magnum and the posterior ex- 

 tremity of the occiput ; but this interval is no where so 

 considerable as in the human subject; and in proportion as 

 it is increased, does the direction of the occipital foramen 

 approach more to the horizontal one. 



Animals of the monkey kind exhibit a closer resemblance 

 of the human structure, in the position and direction of the 

 occipital foramen, than any others. In the orang-utang it 

 is twice as far from the jaws, as from the back of the head f; 

 and it is considerably inclined downwards, so that a line 

 drawn in its level passes below the lower jaw, instead of 

 going just under the orbit, as in man. 



The difference in the direction of the foramen may be 

 estimated, by noting the angle formed by the union of a line 

 drawn in the manner above mentioned, according lo the 



* The ligamentum nuchas or suspensorium colli, which is confounded in the 

 Physiological Lectures (p, 116,) with the yellow ligaments connecting tlxe 

 plates of the spinous processes, is affixed at one end to the spines of the cer_ 

 vical and dorsal vertebrae, and at the other to the middle of the occiput, 

 between the two fossae cerebelli. This thick, and powerful ligament affords a 

 steady and constant support to the head of quadrupeds, which would have 

 otherwise needed an immense mass of muscles to sustain it. Such a struc- 

 ture is not required in man, where, if this ligament can be said to exist at all, 

 it is only lui a weak and insignificant rudiment. I do not know how the 

 orang-utang and other monkeys are circumstanced in this respect. Camper 

 however states, that the spinous processes of th<^ cervical vertebrae are very 

 long in (l>e orang-utang (^(Euvres, i. p. 126). And the same circumstances is 

 still more remarkable in the skeleton of the pongo of Batavia, whose enor- 

 mous jaws and face must require the support of a suspensory ligament, 

 probably attached in both animals to the cervical spines. Audebert, Hist. 

 Nat. des Singes : pi. anat. 2, 



+ The effect of this structure in throwing the centre of gravity forwards 

 and thus increasing the difficulty of maintaining the erect position, is particu- 

 laily pointed out by Mr. Abel; Journey in China, p. 322. 



