Cranial capacity

“ 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 34-1/2 cubic inches. ”

“ The great difference physically between man and the anthropoids, aside from man’s talented larynx and erect posture, lies in man’s abnormal cranial capacity. The normal human cranium never contains less than 55 cubic inches of space, while the largest gorilla cranium contains only 341⁄2 cubic inches. This is a difference of 201⁄2 cubic inches. And 201⁄2 cubic inches of thinking matter is an alarming amount to be lacking in a single individual. ”

“ Besides this, there is commonly some abnormality in the shape of the head, or the cranium is distinctly asymmetrical. It has been noted that criminals have a large orbital capacity, that is to say, the bony framework surrounding the eye is so large as to encroach much more than usual upon the space left within the cranium for nervous tissue. The bones of the skull are likely to be thicker and heavier than usual, thus also limiting the cranial capacity. The superciliary ridges often project and give the beetling brow that is sometimes so remarkable. ”

“ Experimentally, it has been ascertained that from 3 to 6 per cent. of the cranial capacity can be taken up by a foreign body without producing compression symptoms—probably owing to the escape of cerebro-spinal fluid into the spinal canal, and the recession of the medulla and cerebellum into the foramen magnum. Furthermore, it would appear that the incidence of compression symptoms is associated with depletion of those cerebral veins which are in closest relation to the compression force. ”

“ On the other hand, it is too small to be compatible with a normal human intelligence, save among individuals of very small stature having a cranial capacity relatively large with reference to their stature and with reference to the average of their race. But, even discarding the teeth and femur about which there is some doubt, the morphologic characters of the cranium from Java suffice to denote a cerebral volume relatively very weak. ”

“ Nevertheless, in examining a sufficient number of skulls, the causes of error may counterbalance each other, and the means may be accepted as giving results sufficiently near the truth. The results obtained by the same observer are especially favourable for comparison, and from them certain results may be obtained. There is no reason, therefore, why the cranial capacity should not be considered as a character well worthy of study. ”

“ There is also apparently no superiority in brain weight in modern over ancient times. The cranial capacity of Europeans between the eleventh and eighteenth centuries, [pg 255] as shown by the cemeteries of Paris, is not appreciably different from that of Frenchmen of today, and the Egyptian mummies show larger cranial capacity than the modern Egyptians. Furthermore, the limits of variation between individuals in the same race are wider than the average difference between races. In a series of 500 white brains, the lowest and highest brains will differ, in fact, as much as 650 grams in weight. ”

“ As regards cerebral increase, it proceeds with such slowness that we can scarcely affirm the fact has been established at all for our European races since prehistoric times. But the cranial capacity of the Pithecanthropus surpassed by about 300 grams that of the largest gorillas. ”

“ Overlapping between races is accordingly particularly marked in cranial capacity. Furthermore, the measurement obviously cannot be taken on the living. In spite of its interest as an alleged and perhaps partially valid index of mental faculty, cranial capacity is thus of restricted value in distinguishing races. ”

“ Thus, even in the important matter of cranial capacity, Men differ more widely from one another than they do from the Apes; while the lowest Apes differ as much, in proportion, from the highest, as the latter does from Man. ”

“ The average cranial capacity of the adult male head is, I believe, about 90 cubic inches. Cuvier's is reported to have been about 118, In the case which I now record it must have been about 108.—Lancet.
↑ A case is recorded in the "British Medical Journal," October 26, 1872, by Dr. Morris j in which a brain examined at University College, London, weighed 67 ounces. It was that of a bricklayer, who could neither read nor write. ”

“ The capacity of the cranium is estimated in cubic measure by filling it with sand, &c., with the general result that the civilized white man is found to have a larger brain than the barbarian or savage. Classification of races on cranial measurements has long been attempted by eminent anatomists, and in certain cases great reliance may be placed on such measurements. Thus the skulls of an Australian and a Negro would be generally distinguished by their narrowness and the projection of the jaw from that of any Englishman ”

“ Apply this spinal branch of phrenology to the Sperm Whale. His cranial cavity is continuous with the first neck-vertebra; and in that vertebra the bottom of the spinal canal will measure ten inches across, being eight in height, and of a triangular figure with the base downwards. As it passes through the remaining vertebrae the canal tapers in size, but for a considerable distance remains of large capacity. Now, of course, this canal is filled with much the same strangely fibrous substance—the spinal cord—as the brain; and directly communicates with the brain. ”

“ The cranium is of unusual size, and of a long-elliptical form. A most remarkable peculiarity is at once obvious in the extraordinary development of the frontal sinuses, owing to which the superciliary ridges, which coalesce completely in the middle, are rendered so prominent, that the frontal bone exhibits a considerable hollow or depression above, or rather behind them, whilst a deep depression is also formed in the situation of the root of the nose. The forehead is narrow and low, though the middle and hinder portions of the cranial arch are well developed. ”

“ 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. ”

“ 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 cerebral cranium of the ape is not only smaller but it is furnished with strong bony ridges, to [Pg 190] serve as points of attachment for powerful muscles intended to protect the cranial cavity. The human skull is completely devoid of such ridges; it is perfectly smooth, with delicate contours; it might be described as "frail and naked"; for the word nakedness precisely expresses the absence of those defences with which the cranium of the anthropoid ape is so abundantly provided. Accordingly, the human cranium is undefended by soft tissues ”

“ Should only temporary benefit be secured, the operation should be repeated. Experience alone can demonstrate whether the expansion of the brain will be able to spread the cranial bones to such an extent that it may reach even an ordinary development. ”

“ The brain has a natural tendency to remain at rest, but is liable to be brought into a state of commotion by impulses on the cranium being communicated to it. When a slight blow is inflicted on the skull, only a slight commotion of the brain is induced, the cranial contents are, as it were, slightly jumbled, and a temporary and trifling confusion of its functions follows. ”

“ The new doctrine he expounded was received in Germany with great enthusiasm by the school of the philosophers of nature. The author conceived the cranium to consist of three vertebræ, and the basal occipital, the sphenoid, and the ethmoid, were regarded as the central parts of these cranial vertebræ. On these alleged bodies of vertebræ, the arches enveloping the central parts of the nervous system were raised, while on the opposite side were attached the inferior pieces, which went to form the vegetative arch destined to embrace the intestinal canal and the large vessels. ”

“ Frequently craniometry serves to verify cranioscopy. For example, a cranium may appear to the eye too large or too small, but certainly if we measure the cranial circumference with a tape-measure we shall have an accurate decision of a case which may well be a simple optical illusion. Indeed, we all know how easy it is to give an erroneous judgment, relying only on our senses ”

“ As the growth of bone is more active in infancy and youth than in the adult, the adhesion between the dura mater and the cranial bones is greater in early life than at maturity. From the inner surface of the dura mater strong bands pass into the cranial cavity, and form partitions between certain of the subdivisions of the brain. A vertical longitudinal mesial band, named, from its sickle shape, falx cerebri, dips between the two hemispheres of the cerebrum. ”

“ Great changes have been effected in the head, resulting in a diminution of the cranial flexure. This diminution is nevertheless apparent rather than real, and is chiefly due to the rapid growth of the rudiment of the cerebral hemispheres. ”

“ Up to a certain stage the growth of the brain determines the capacity of the skull. Then it seems as though more complex convolutions accompanied the packing of the elaborated cerebral mass within the fixed limits of its osseous chamber.
A comparison of races, based on minute investigation of an adequate number of brains of fair typical examples, may be expected to yield important results; but in the absence of such direct evidence, the chief data available for this purpose are derived from measurements of the internal capacity of their skulls. ”

“ IT is not easy to say at what date or period of science, the eminences and various inequalities on the surface of the human skull first became particular objects of attention among medical men. They could not have escaped notice after the operation of trepan, or perforation of the cranium, when its fracture, or other diseases occasioning compression of the brain, had once been introduced; for, in that operation, such inequalities greatly increase its hazard, and call for the strictest attention from the most reckless practitioners. ”

“ The cranial and facial characteristics, which are the result in man of the considerable volume of his brain, the atrophy of the nasal fosses, and of their numerous posterior cavities, which has brought about the disappearance of the muzzle, the compensatory perfection of the touch and the vision, which, with the modifications necessitated by the equilibrium of the skull, have contributed to a bipedal attitude and an entire new series of differential characteristics—are details also. ”

“ The arrangement of the cranial nerves in the adult has frequently been used in morphological investigations about the skull, but there are to my mind strong grounds against regarding it as affording a safe basis for speculation. The most important of these depends on the fact that nerves are liable to the greatest modification on any changes taking place in the organs they supply. ”

“ The cranial bones with the adherent dura are then pressed outward from the brain, and are either held in this position or cut through with the bone-shears so that sufficient room for the removal of the brain is afforded. The anterior falx is then cut and the brain removed as in the adult, using great care because of its very soft consistence. When too soft to be removed the brain may be opened within the skull; or a horizontal section may be made with the large, flat brain knife at the level of greatest circumference. ”

“ When the circulation of the brain is vigorous and regular, all portions being in regular activity, the fulness of the circulation being shown in the face, we may be sure that the character is fairly indicated by the cranium. The younger the individual the thinner the cranium, and the less the liability to deception by the thickness of the bones. Female skulls are generally more delicate than male, and also more normal or uniform in their circulation. ”

“ 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. ”

“ It is generally stated that the cranial flexure is at its maximum at the stage represented in these figures, and there can be no doubt that viewed from the exterior the cranial flexure ceases to be so marked a feature, and finally disappears as the embryo gradually grows older; but though the mid-brain ceases to form the termination of the long axis of the embryo, the flexure of the brain becomes in many forms absolutely more marked ”