Craniometry

“ The fourth subdivision of craniometry is closely allied to that which has just been described, and it deals with the comparison of the prehistoric and the recent types of mankind. The methods are exactly similar to those employed in the comparison of living races; but in some particular instances where the prehistoric individual is represented only by a comparatively minute portion of the skull, some special modifications of the usual procedures have been necessitated. ”

“ Tyson explains that the measurements he made of the skull of that animal were devised with a view to exhibiting the difference between this and the human skull.
The artists did not carry their researches very far. The anatomists on the contrary continued to make measurements, and in 1764 Daubenton published a noteworthy contribution to craniometry. Six years later, Pieter Camper, distinguished both as an artist and as an anatomist, published some lectures containing an account of his craniometrical methods, and these may be fairly claimed as having laid the foundation of all subsequent work. ”

“ There are at the outset difficulties in marking the plane accurately on the skull, and it is to be deplored that the anthropologists of different nations should have allowed themselves to be affected by extraneous influences, which have hindered their unanimous agreement upon some one definite horizontal plane in craniometry. ”

“ But the roofs of the orbits rise more obliquely into the cranial cavity, thus diminishing the space for the lower part of the anterior lobes of the brain, and the absolute capacity of the cranium is far less than that of Man. So far as I am aware, no human cranium belonging to an adult man has yet been observed with a less cubical capacity than 62 cubic inches, the smallest cranium observed in any race of men by Morton, measuring 63 cubic inches; while, on the other hand, the most capacious Gorilla skull yet measured has a content of not more than 341⁄2 cubic inches. ”

“ The skull consists of a cartilaginous cranium, and of jaw and visceral arches. The cranium persists throughout life, in what closely resembles a transitory embryonic condition of the higher types. There is a nasal capsule (na.c.) , a brain case proper, and lateral otic (auditory) capsules (ot.c.) containing the internal ear. (This should be compared with the frog's embryonic skull.) The upper jaw has a great bar of cartilage, the palato-pterygoid, as its sole support; the arch of premaxilla, maxilla, jugal, and squamosal-- all membrane bones-- is, of course, not represented. ”

“ Nor should we be justified in regarding the cranial conformation as perhaps representing the most savage primitive type of the human race, since crania exist among living savages, which, though not exhibiting such a remarkable conformation of the forehead, which gives the skull somewhat the aspect of that of the large apes, still in other respects, as for instance in the greater depth of the temporal fossæ, the crest-like, prominent temporal ridges, and a generally less capacious cranial cavity, exhibit an equally low stage of development. ”

“ The cranium is large in proportion to the size of the body. The skull is in the form of a wide oval and is wider than it is long. The elements of the skull were ornamented with a coarse sculpturing which partakes of the nature of incomplete radiations on the squamosal region. The different elements of the cranium can not be distinguished, although I think the outlines of the parietal are indicated. The position of the nostrils is well forward and they are slightly elongate transversely. The pineal foramen can not be determined. ”

“ The Veins that bring back the Blood from the Substance of the Brain, are emptied into the Sinus's of the Dura Mater, which are all discharg'd into those that are call'd Lateral, which last go out of the Skull immediately under the Nerves of the eighth Pair, thro' the hinder-part of the Hole made by the meeting of the Occipital Bone, and the Apophysis Petrosa. These Lateral Sinus's fall into the Internal Jugulars, which are receiv'd into a considerable Sinking hollow'd on each side in the outward, part of the Basis of the Skull, which is nam'd the Pit or Hole of the Internal Jugular. ”

“ But the fact is that some skulls are only one-eighth of an inch thick and some are a full inch in thickness. And there is no certain way of telling just how thick a skull is, except by an examination of its interior and not every subject is willing to undergo this inconvenience. The phrenologist may thump it with his knuckle and sound it, but he can never be certain how near he is to the brain nor how much brains are within. And still again, nearly every skull has thin parts and thick parts, and in some heads there are actual cavities in places. ”

“ One of these tracks was cut on each side, the surgeon explained, because it would give equal expansion to the two sides of the brain, and because it would cause death to cut through the middle of the top of the head, where lies "the superior longitudinal sinus." He left, therefore, the solid track of bone through the middle, and cut two grooves or tracks through the bone, one on either side, where nature (when she does not make a mistake) leaves soft or yielding edges, by means of which the normal skull expands to fit the needs of the brain within. ”

“ The human bones include the cranium and lower jaw (broken, but the pieces nearly all present and easily replaced in exact position) , a few vertebræ and long bones, several ribs, phalanges, and metacarpals, clavicle, astragalus, calcaneum, parts of scaphoid, ilium, and sacrum. The ensemble denotes an individual of the male sex whose height was about 1.60 meters. The condition of the sutures and of the jaws proves the skull to be that of an old man. The cranium is dolichocephalic, with an index of 75. ”

“ In the shafts of the long bones, owing to the excessive absorption of bone, the cortex becomes porous, the spongy bone is rarefied, and the bones readily bend or break under mechanical influences. When the disease is arrested, a process of repair sets in which often results in the bones becoming denser and heavier than normal. In the flat bones of the skull, the absorption may result in the entire disappearance of areas of bone, leaving a membrane which dimples like thin cardboard under the pressure of the finger—a condition known as craniotabes. ”

“ Adults.—Sutures of skull, and those between epiphyses and shaft of long bones obliterated except that, in some mice, sutures of skull persist between frontoparietal, and interparietal; cusps of molars so worn that dentine occlusally confluent; small island of enamel in third upper and lower molars of some specimens; relative to length of skull, cranium lower, rostrum longer, and interorbital region narrower than in subadult; cranium appears to be more flattened dorsoventrally; between subadult and adult stages, principal growth occurs in basioccipital, basisphenoid, frontals, and parietals ”

“ A little anatomical knowledge will prevent us from being deceived, and enable us to make due allowances. There are no great difficulties in making a correct estimate, and the anatomists who have taught their pupils that correct cranial observations could not be made, only showed their own ignorance of the subject. We must consider the cranium as though all osseous protuberances had been shaved off, leaving the smooth, curving contour of the skull. ”

“ They include the cranium, nearly entire, with the teeth and part of the os hyoides; the seven cervical, eight of the dorsal, and five of the sacral vertebræ, the two scapulæ, left humerus, radius and ulna, two carpal bones, and an ungueal phalanx; both femora, the proximal extremities of the left tibia and fibula, and the left astragalus.
The principal parts of the cranium which are deficient are the anterior extremities of both the upper and lower jaws, the os frontis, æthmoid bone, and the whole upper part of the facial division of the skull ”

“ It has more recently been shown by Levi that the same thing is true for man. K. Gegenbauer has pointed out that the primitive membranous skull shows, in the chordal region, signs of metameric segmentation in the way in which the cranial nerves pierce the dura mater one 'behind the other. These segments, however, had lost their distinctness even before the cartilaginous cranium had become developed, so that there is no real segmental value in the elements of this, still less in those of the bony skull. ”

“ When the skull-cap is ready to come off one will feel it 'wobble.' Insert then the hook under its forward end and pull firmly. The bony skull-cap alone will come away, leaving the periosteum of the inner surface adhering to that of the base of the skull, enveloping the brain, and forming the so-called dura mater or outer one of its 'meninges.' This dura mater should be slit open round the margins, when the brain will be exposed wrapped in its nearest membrane, the pia mater, full of blood-vessels whose branches penetrate the tissues. ”

“ The nasal skeleton, the palate, the orbit, the teeth, and the mandible were investigated in turn, and at last all the individual bones of the cranium and face, their irregularities of outline, and their relations to one another, were subjected to the closest examination and most subtle measurements, with instruments of extreme delicacy of construction and ingenuity of design, till, finally, the trifling number of five thousand measurements for every skull found an advocate in the person of the Hungarian Professor V. Török (whereby the wealth of detail obscured the main objects of study) ”

“ The limb bones are long, slender, and less curved than those of the other associated human beings (A) , and herein the earliest type is suggested once more. [Pg 62] But the differences occur now in the skull. The brain is as large as in the other subdivision (A) and in modern men. The brain-case is becoming elevated: the brow-ridges are undergoing reduction; this process, commencing at their outer ends, expresses to some extent the degree of reduction in the muscles and bone of the lower jaw. The teeth are smaller and the chin becomes more prominent. ”

“ The skull, which must have consisted of hardened cartilage, exhibits pairs of nasal and auditory capsules, with a gill-apparatus below its hinder part, but no indications of ordinary jaws. The anterior opening of the brain-case is surrounded by a ring of hard cirri. A pair of “post-bronchial plates” projects backwards from the head. The vertebral axis shows a series of broad rings, with distinct neural arches, but no ribs. Towards the end of the body both neural and haemal arches are continued into forked radial cartilages, which support a median fin. ”

“ T i a, tentorial angle; d a b, olfactory angle; e f b, cranio-facial angle; g h, extreme length of the cavity which lodges the cerebral hemispheres or 'cerebral length.' The length of the basicranial axis as to this length, or, in other words, the proportional length of the line g h to that of a b taken as 100, in the three skulls, is as follows:—Beaver 70 to 100; Lemur 119 to 100; Baboon 144 to 100. In an adult male Gorilla the cerebral length is as 170 to the basicranial axis taken as 100, in the Negro (fig. 30) as 236 to 100. In the Constantinople skull (fig. 30) as 266 to 100. ”

“ When ossification sets in, the ear-capsule forms three bones, of which two fuse with the supraoccipital and exoccipitals.
During the formation of the ear-capsule the cranial basis develops from a plate to a trench, for in its hinder section the side parts grow up to form the side walls of the brain, in exactly the same way as the processes of the vertebral rudiments grow up to enclose the spinal column (pp. 122, 192) . The foundations of the skull are now complete, and ossification gradually sets in.
Fig. 11.—Embrionic Cranium of the Adder. Ventral Aspect. (After Rathke.) ”

“ The skull is typically autostylic. Along {224}the whole length of its dorsal border the palato-quadrate cartilage is fused with the inferior lateral margin of the cranium from the periotic to the olfactory region, thus forming a triangular plate of cartilage, the base of which is continuous with the cranium, while the downwardly directed apex provides an articular surface for the lower jaw. The hyoid arch is little better developed than the succeeding branchial arches, and includes a vestigial hyomandibular, an epi-hyal, and a cerato-hyal. ”

“ We are convinced that even if the skull had been complete, it would not have been possible to pronounce, with certainty, upon a single specimen; for individual variations are so numerous in the crania of one and the same race, that one cannot, without laying oneself open to large chances of error, draw any inference from a single fragment of a cranium to the general form of the head to which it belonged. ”