and parietal eminences, does not, as I have already stated, disappear with the advance of life from infancy to adult age. Its persistence may not improbably be connected with the fact of its being situated on the posterior aspect of the head-a point least capable of being protected from injury.

During the early condition of cranial development, the frontal bone consists of two lateral segments, divided by a median suture which usually disappears at a later period, but sometimes remains distinctly perceptible throughout life. It is extremely important to bear in mind this occasional persistence of the frontal suture, for it might otherwise, perchance, lead you to a serious diagnostic error, in a surgical point of view. Suppose, for example, an adult person is brought before you who has received a severe blow on the forehead that is attended with urgent cerebral symptoms-symptoms of such a nature as to place you in doubt respecting the existence of a fracture, with depressed bone. You give the patient the benefit of this doubt, and you expose the os frontis with a scalpel at the seat of injury. But do not hastily conclude, on meeting with a vertical line in the osseous surface, that it is necessarily a fracture, for in this particular case it might not impossibly be due to an unobliterated frontal suture. With a little attention, however, and with a knowledge of the following distinctive characters, you may quickly arrive at a solution of the question. In a suture there is a minutely serrated, or zigzag appearance, which is never observable in a fracture; and conversely, in a fracture, there is a dark line, formed by a thin layer of blood, occupying the fissure between the fractured surfaces, which is never perceptible in a cranial suture. By such means,

ANTERIOR FONTANELLE, ITS DIAGNOSTIC VALUE. 23

a diagnosis between a fracture and a suture may always at once be easily established.

The anterior fontanelle, which is situated between the frontal bone and the anterior superior angles of the two parietal bones constitutes a portion of the membranous structure existing between the bones of the cranium, at the commencement of extra-uterine life. Its condition, if properly interpreted, often forms an indication of great practical value in the treatment of infants. When the

arterial circulation is in a natural state of vigour and activity, the anterior fontanelle is observed on a level with the surrounding parts. If from some cause, the circulation be unduly excited, it is raised, or rendered tense and more prominent; but if, on the contrary, the circulation be enfeebled, it is lowered or depressed below the contiguous structures. I know, in fact, of no sign, that so clearly and correctly indicates the state of the vital powers of the infant, as this easily recognisable condition of the anterior fontanelle. If on a tactile examination, it be found considerably depressed, it forms one of the strongest marked indications that can be encountered, of feebleness and debility for it is an evidence of the power at the centre of circulation being inadequate to the supply of the cranial contents with their normal quantity of blood.

There are several foramina that perforate the osseous parietes of the cranium, in order to give exit to veins and thus provide for the free escape of venous blood from the interior of its cavity. Of those which are met with in childhood, some remain permanent through life, whilst others become obliterated on the attainment of adult age. Thus, the outlets in the child for the escape of venous blood from the cranial cavity, are the foramen

cæcum, the sphenoidal fissures, the foramina parietalia, the posterior lacerated foramina, the foramina mastoidea the posteior condyloid foramina, and the foramen magnum. Whilst, in the adult cranium, the foramen cæcum, and usually the foramina parietalia, have become obliterated or impervious.

The existence of such numerous channels for the escape of venous blood from the interior of the skull, is in wise harmony with the peculiar situation under which the cranial contents are placed with respect to the circulatory system. It must be borne in mind, that the brain, an organ of a structure so delicate, and of a function so vitally important, is situated within a hard unyielding case; which, resisting temporary pressure, does not in the slightest degree afford accommodation to the state of the circulation within. The brain, therefore, being thus confined, and rendered incapable of undergoing temporary enlargement or expansion, would be seriously exposed to injurious compression, on every sudden excitement that increased the action of the heart, and augumented the activity of vascular supply, were there not so free an egress provided for the escape of venous blood.

Regarding these foramina in this point of view, they become invested with considerable functional importance; and we at the same time obtain an insight into the probable reason connected with the disappearance of those which become obliterated with the attainment of adult age. During the growth and development of the brain, its circulation is more active, and its vascular supply, comparatively larger, than at a later period, when it has arrived at its full dimensions. It is easy to understand, therefore, that a less provision is required in

MORE NUMEROUS IN CHILD THAN ADULT.

25

the latter than in the former condition for the escape of venous blood from within the osseous walls of the cranium.

But, there is yet another point of view, under which the temporary existence of these foramina bears a still more interesting physiological aspect. Children, whose actions are more influenced by sudden emotions, and less governed by the exercise of reason and judgment than adults, often exhibit prolonged fits of passionate crying; which, produce a considerable, though temporary excitement, or increase of vascular action, and would often place them in imminent peril of their lives, were there not such efficient means provided for the rapid escape of blood from the interior of the cranial cavity under these sudden emergencies. Adults, on the other hand, having higher developed mental endowments, are more able to control their actions, and in some measure to check those fits of passion which lead to such increased vascular excitement of the cerebral organ.

These foramina, then, for the egress of venous blood from the cranial cavity, which are peculiar to a period of youthful life, can, as they have but a temporary existence, only be associated with a temporary function. And this function, as I have just endeavoured to explain, is probably connected with the comparatively greater supply of blood the brain receives during its period of growth and development, and with the paroxysms of sudden excitement, to which the cerebral circulation of the child is so frequently exposed.

The foramen cæcum is situated in close connection with the nose, and the vein it contains communicates with the anterior extremity of the longitudinal sinus. Now, there seems in this arrangement, an explanation for the frequent epistaxis of children, which, I believe, most

generally arises from rupture of a branch of this vein and which may hence be regarded as a conservative measure employed by nature, for relieving the cerebral circulation when in too loaded or plethoric a condition.

The foramina parietalia, which as a general rule, like the foramen cæcum, have only a temporary existence, like it, also, derive the current of blood they give passage to, from the longitudinal sinus. Whilst the other foramina, which remain pervious through life, exclusive of the foramen magnum and great fissures at the cranial base, namely, the mastoid and posterior condyloid, transmit veins that derive their blood from the lateral sinuses.

The superficial position of the mastoid vein on its escape from the cranial cavity, forms a point of importance, when viewed in relation to the practical part of our profession. From its connexion with the lateral sinus, on the one hand, and from the superficial position of its exit, on the other, it furnishes an easily available resource for relieving congestion of the cerebral circulation; and one which is often resorted to in practice for such a purpose. By the application of leeches or cuppingglasses behind the ears, blood is removed from the structures in the immediate vicinity of the mastoid foramen, thus facilitating the more rapid escape of blood through the mastoid vein from the lateral sinuses, and in this way, directly diminishing the amount of venous tension existing within the cranium.

The ophthalmic vein, issuing from the cavernous sinus, emerges from the cranial cavity through the sphenoidal fissure, and traversing the orbit, reaches the soft structures on the exterior of the face. Its trunk being destitute of valves (like the venous sinuses and