660 



SKELETON. 



The fifth or anterior sphenoid costo-verte- 

 bral quantity consists of (B) the centrum and 

 the part 1", as the neural spine. The costo- 

 sternal quantity of this vertebra is represented 

 by (b) the palate bone. 



The sixth or ethmoidal costo-vertebral 

 quantity of the head consists of (A) the cen- 

 trum, with the part 1' as the neural arch. The 

 costo-sternal quantity is represented by the 

 nasal bones (a). 



Now, considering^. 481. as a whole, I find 

 it to be characterised in certain ways, which 

 still further prove the nature of the fact, that 

 the human head consists of six* costo- 

 vertebral archetypes, as numbered above ; and 

 though I by no means would have it under- 

 stood that I consider each of those cranial 

 archetypes to be equal in quantity either to 

 one another or to the first sterno-costo-ver- 

 tebral quantity of the thorax, still I find that 

 there are certain sutural marks in the human 

 head and facial apparatus, which seem to 

 define, with sufficient clearness, those natural 

 groups of bones which form the archetypal 

 quantities. The spaces called intervertebral, 

 amongst the spinal vertebrae, viz. those spaces 

 which occur between the neural arches of two 

 adjacent vertebrae, such as G and H,are repre- 

 sented by all the transverse sutures of the 

 cranium. Those sutural intervertebral inter- 

 vals I have marked thus : Between the axis H 

 and the atlas G, the intervertebral space is 

 o" /////r ; between the atlas G and the occipital 

 form, the space is o"" ff ; between the latter 

 and petrous form is the lambdoidal suture 

 o'"", and so on. The intercostal spaces are 

 marked q, q, &c. 



When we seek to determine the nature of 

 the sutures of the cranial structures by com- 

 parison with the serial vertebrae of spinal 

 order, we should bear in mind the fact that 

 one order of the cranial sutures must cor- 

 respond to the intervertebral spaces of spinal 

 vertebrae, while another order of cranial 

 sutures must answer to those points where 

 the elements constituting each vertebra join. 

 Thus, whilst such sutures as the coronal 

 (fig. 481. </,) and lambdoklal (</"") answer to 

 the intervertebral spaces (o /////// ), the sutural 

 temporo-parietal point of union between 1"" 

 and 2 answers to the point of junction be- 

 tween the elements 1, 2 of the atlas vertebra 

 G, or of the axis H. The frontal suture is that 

 line of union which the symmetrical laminae of 

 one vertebra ot the spine would, when meeting 

 each other at the median line of neural space, 

 represent. The sagittal suture is a biclevage 

 of the spinous process (viz. the symmetrical 

 parietal bones) of that vertebra of the head 

 to which they belong. 



As the nerves passing from the spinal cord 

 bear a somewhat fixed relation to spinal ver- 



* Professor Owen enumerates four cranial verte- 

 brae, viz. the occipital, parietal, frontal, and nasal. 

 He regards the ethmoid to be a sense capsule, like 

 the petrosal bone, neither of which he considers to 

 be parts of vertebrae. Oken held the same opinion. 

 Spix, Bojanus, and Geoffrey left these bones unde- 

 termined as to their homological signification. 



tebrae, so might we expect that the nerves of 

 the encephalou should bear the like relation- 

 ship to the cranial vertebral quantities. A 

 spinal nerve passes between two adjacent ver- 

 tebrae, and thus to six spinal vertebrae there 

 correspond five nerves. I have enumerated 

 six cranial vertebrae, each one with the costal 

 quantity, and hence the nerves passing between 

 these six should number five, like those of the 

 spine. These cranial nerves I consider to 

 form five natural groups, as follow : 



The first or olfactory nerve, being one of 

 special sense, is distributed upon the ethmoid 

 vertebra (Jig- 481. A). The second is a group 

 of motor and sensory branches, consisting of 

 the optic, the third, and the fourth nerves, 

 which pass through the optic and lacerate 

 foramina or cleft, which occurs between the 

 ethmoid and anterior sphenoid vertebrae. 

 The third group of nerves is motor and sen- 

 sory, consisting of branches of the fifth, which 

 pass through the foramen ovale (fig. 482. e). 

 The fourth group of nerves is motor and sen- 

 sory, consisting of the portio mollis and portio 

 dura ; one of these nerves is distributed to 

 the organ of hearing, and the other makes exit 

 at the stylo-mastoid foramen (Jig. 482. r r), 

 being destined for the side of the face. The 

 fifth group is also motor and sensory, and 

 consists of the eighth and ninth nerves pass- 

 ing out through the foramina (/, ), viz. the 

 anterior condyloid and foramen lacerum pos- 

 terius. 



The groups of foramina, which I consider 

 as answering to the intervertebral foramina of 

 the spinal series, are indicated in fig. 482., each 

 group being surrounded by a dotted line, as at 

 the point e, the place s, m t r t and the place /, t. 

 The other two intervertebral foramina are not 

 seen in this view of the cranial base.- It is a 

 singular fact that the external meatus occurs 

 like a true intervertebral foramen between the 

 petrosal and temporal vertebrae, which in the 

 early foetal condition are naturally separated. 

 When I view the serial order of the inter- 

 vertebral foramina of the cervical spine, I find 

 that the external meatus exactly coincides 

 with the series. 



There are many facts of interest which re- 

 cur to me regarding fig. 482. as a form com- 

 parable to vertebrae ; but since to record 

 these in full would exceed the space allotted 

 to this article, I must forego the task, and 

 only remark in brief, that ail the other fora- 

 mina of the cranial base give passage to 

 arterial and venous vessels like the vertebral 

 foramina (g g) of the atlas and (/* h) of the 

 axis. 



The cranial base (fig. 482.) gives evidence 

 of a certain fact of special modification of so 

 large an interest, that I cannot but advert to 

 it : the fact is this the body of the axis (8, 8) 

 passes through the body of the atlas (7, 7), 

 and carries part of this latter (q, q) before it 

 as its odontoid process. The body of the oc- 

 cipital vertebra (6, 6), passing forward to the 

 body [of the post sphenoid vertebra (3, 3), 

 sunders the body of the petrosal vertebra 

 (5, 5), while the body of the parietal vertebra 



