Temporal bone

“ Temporal bone, a very complex bone situated in the side of the skull of most mammals and containing the organ of hearing. It consists of an expanded squamosal portion above the ear, corresponding to the squamosal and zygoma of the lower vertebrates, and a thickened basal petrosal and mastoid portion, corresponding to the periotic and tympanic bones of the lower vertebrates. ”

“ Fig. 15.—Cranium at birth, showing sutures and fontanelles.
The frontal bone, as its name implies, forms the fore part of the head or forehead. It joins the parietal bones above and the temporal bones on either side. At the lower edge are the supra-orbital arches, each with a supra-orbital notch or foramen on its inner margin for the passage of the supra-orbital vessels and nerve, the nerve most affected in neuralgia. Just above the arches on either side are the superciliary ridges, behind which, between the two tables of the skull, lie the frontal sinuses. ”

“ The bones of the cranium seen by looking down into the basis of the skull, as above, are the frontal bone over the eyes, the sphenoid bone, behind the sockets of the eyes, extending from the right to the left temple, the temporal bones, forming the ridge that holds the apparatus of hearing, and extending up about two inches on the side head, and the occipital bone at the back, between the two temporals, meeting the sphenoid bone in the centre of the base. ”

“ Feeling as of knife stabs under the right temporal bone extending into the right eye and becoming worse on bending over. On the outside of the forehead a pressing pain which seems to thrust inward, passing, in half an hour, into the inside of the head. ”

“ On the inner surface the frontal sulcus for the longitudinal sinus runs along the median line.
The parietal bones are the side bones of the skull. They meet [Pg 50] each other in the sagittal suture at the median line above and join the frontal and occipital bones at either end, while below they touch upon the temporal bones, the temporal muscles being attached in part along their lower surface. These muscles are inserted into the coronoid process of the lower jaw, which they thus help to raise and to retract. ”

“ The semicircular line indicating the upper boundary of the attachment of the temporal muscle, though not very strongly marked, ascends nevertheless to more than half the height of the parietal bone. On the right superciliary ridge is observable an oblique furrow or depression, indicative of an injury received during life. 7
mm. 8 The length of the skull from the nasal process of the frontal over the vertex to the superior semicircular lines of the occipital measures.............................303 (300) = 12.0". ”

“ Upon the top of the head, and covered with hair is a large unequal depression and elevation–a quadrangular fragment of bone, which was entirely detached from the frontal, and extending low down upon the forehead, being still raised and quite prominent. Behind this is a deep depression, two inches by one and one-half inches wide, beneath which the pulsations of the brain can be perceived. ”

“ His body has long since mouldered away and mingled with the parent earth,—this skull alone remains; and yet the time will surely come, and cannot be far distant, when "the bones shall come together—bone to his bone"; when the sinews and the flesh shall come upon them, the skin cover them, and the breath entering the body the dead shall live! ”

“ And this may possibly be the reason why the bones of the skull, though not exposed to forces such as those which produce, in other bones, dense outer layers including less dense interiors, nevertheless repeat this general trait of bony structure. While, however, it is beyond doubt that some bones are not due to the direct influence of mechanical stress, we may, I think, conclude that mechanical stress initiates bone-formation. ”

“ While the growth of the bones occurs, of course, mainly during the earlier years of life, yet they do not attain their full maturity until about the twenty-fifth year; and it is stated that in persons devoted to intellectual pursuits, the skull grows even after that age. It is plainly necessary that during this period of bone growth the nutrition of the body should be of the best, that the bones may be built up from pure blood, and supplied with all the materials for a large and durable framework. Else the body will be feeble and stunted, and so through life fall short of its purpose. ”

“ In young persons whose heads from disease have become fixed either sideways or backwards, one of the eyes has changed its position, and the bones of the skull have been modified; and this apparently results from the brain pressing in a new direction.213 I have shewn that with long-eared rabbits, even so trifling a cause as the lopping forward of one ear drags forward on that side almost every bone of the skull ”

“ A temporal hæmatoma is always highly suggestive of a fracture involving the temporal fossa, especially in the event of marked outward bulging, with stretching and discoloration of the overlying tissues. ”

“ Fortunately, this is not necessary for the general reader, who requires only to understand the position of the organs in the head, and the direction of their growth, which is in all cases directly outward from the central region or ventricles, so as to cause a prominence of the cranium—not a “bump,” but a general fulness of contour. Bumps belong to the growth of bone—not that of the brain.
Let us next consider the genesis of the brain, which will give us a more perfect understanding of its structure, by showing its origin, the correct method of estimating its development. ”

“ The Cranial Bones.—The cranium or skull is especially adapted for the protection of the brain and the bones are flat and closely fitted to its surface. They have two layers of bone, the outer and the inner tables, of which the outer is the thicker, and between these is a tissue filled with blood-vessels, the diploë. In the infant, whose brain has not yet attained its full size, opportunity must be left for growth and the skull therefore consists of a number of bones with interlocking notched edges, where growth takes place, but in the adult it forms one solid covering of bone. ”

“ Bone essentially surrounds the nervous mass. The skull environs and incloses the brain, the vertebræ the spinal cord, the ribs, the visceral nerves the snail's shell all the soft parts of that animal, the coral stem its polyp-tube, the horny coat the insect.
1832. The purest and highest antagonisms in an animal are nerve and bone, and as such they are demonstrated on every occasion. The nerve is that which is soft, powerless, changeable, sentient, governing, and motion-imparting; the bone, what is hard, strong, unchangeable, non-sentient, governed, and becoming moved ”

“ The bones, though the hardest, are the most delicate parts in the whole body; but when it is affected, nature forms a new periosteum over the sound part, and gradually pushes forward the decayed scale. This wonderful work is performed by nature only, and must not be disturbed. By scraping, and boring of it, the tender periosteum will only be molested, the sound bone will become foul again, and so you may go on for ever; and I never saw a sore of that kind healed up by this improper method, till nature over-powered art, or the surgeon was tired with scraping, perforating, &c. ”

“ At the end of about three weeks, if you make a section of the callus, minute specks of earthy matter are visible, deposited in it here and there, and at the same time some of the callus, appears to disappear on the outside, so that the neighboring muscles and tendons no longer adhere to it. The specks of bone become larger and more numerous until they extend into each other; and thus by degrees the whole of the callus is converted into bone. ”

“ Through correlation with the protuberance of the skull, the shape and even the relative connection of the premaxillary and nasal bones, the shape of the orifice of the nostrils, the breadth of the frontal bone, the shape of the post-lateral processes of the frontal and squamosal bones, and the direction of the bony cavity of the ear, have all been modified. The internal configuration of the skull and the whole shape of the brain have likewise been altered in a truly marvellous manner. ”

“ If we take a transverse section of the bones of the cranium, we find that they are formed of two very thin layers of bone united by a porous, osseous substance; the external layer is in direct contact with the muscles of the scalp, and the internal layer with the brain. ”

“ Thus bones are not dry, lifeless substances, but are the very type of activity and change. In life they are richly supplied with blood from the nutrient artery and from the periosteum, by an endless network of nourishing canals throughout their whole structure. Bone has, therefore, like all other living structures, a self-formative power, and draws from the blood the materials for its own nutrition. ”

“ In the interior of the skull should be noticed a large plate of bone which extends inwards and separates the great brain, or cerebrum, from the lesser brain, or cerebellum, and prevents the jarring of that important organ likely to arise from the animal’s vigorous movements. ”

“ A positive strain represents stretching, whilst compression is represented by a negative figure. Direct experimental measurements in a human showed that the strain levels in the parietal bone of the skull are 10 fold lower compared with the tibia [4] . ”

“ Convolutions that are frequently called into action become better supplied with arterial blood, expand and grow, while the adjacent portion of the inner plate of the skull becomes absorbed, and presents a remarkable indentation. Convolutions that are seldom in action shrink in size, and the adjacent bone grows in upon them. Thus the skull becomes thinner at the site of every active organ, and thicker over every convolution that is inactive. ”

“ After the brain has been removed, the skin is stripped off a limited area of the skull, and the bone at the place of junction of the sagittal and lambdoid sutures above the occipital foramen is filed away, so that only a point, like a bony outgrowth, is left. ”

“ While your body is alive, there is a hard frame-work inside of it, upon which the soft flesh is fixed, in order that it may be kept in a convenient and durable form, and around which the water is packed in a countless myriad of chambers, and vessels, and porous fibres. The hard internal frame-work is composed of what are called bones. In the dried mummy, left when the moisture is all gone from the body, there are rather more than nine pounds of this mineral bone-substance. ”

“ If the rays are allowed to penetrate for a shorter time the bones show dense shadows, and one can get a light shadow of the soft parts. If the exposure is still shorter, then we can recognize the dense shadow of the bone, the much less dense shadows of the muscles, and the still lighter shadows of the layer of fat immediately under the skin. ”

“ Although the tissue elements in this disease resemble those of a new growth arising in the marrow, they differ in their arrangement and in their method of growth; there is no tendency to erupt through the cortex of the bone, to invade the soft parts, or to give rise to secondary growths.
_Clinical Features._--The onset of the disease is insidious, and attention is usually first directed to it by the occurrence of fracture of the shaft of one of the long bones--usually the femur--from violence that would be insufficient to break a healthy bone. ”

“ A sure means of fixing the date of a wound may be found by noticing the color of the bone that has been attacked. If the wound is recent and slight, the bone will be red; if old and severe, the color will be dark blue. ”

“ Where there are two parallel bones—as in the leg, for example—the growth of the diseased bone may be impaired, and the other continuing its normal growth becomes disproportionately long; less frequently the growth of the diseased bone is exaggerated, and it becomes the longer of the two. ”

“ The upper or alveolar part of the jaw tended to be absorbed and only the later, firmer growth of the lower part of it to be retained. In primitive man probably loss of teeth would materially shorten life. The skull, which generally becomes lighter, may also sometimes become heavier and increase inwardly as the brain shrinks. The rate of the heart varies very little as age advances. ”

“ A very tough skin—a sheathe—surrounds the neck with blood vessels, nerves, muscles, bones, ligaments, fascia, glands great and small, throat and trachea. In bones we find a great canal for spinal cord. It is well and powerfully protected by a strong wall of bone, so no outer pressure can obstruct the flow of passing fluids, to keep vitality supplied by brain forces, but with all the guards given to protect the cord, we find that it can be overcome by impact fluids to such degree as to stop blood and other fluids from supplying lungs and all below. ”

“ If we examine the structures underlying the skin, we find that in the skull the orbits are entirely shut in by a bony wall, so that the finger cannot be passed into the temporal depression behind, as could be done in the Lemurine skull, and that the lachrymal foramen opens within the cavity for the eye. ”

“ If, however, apposition is not perfect, some of the new bone is permanently required and some of the old bone is absorbed in order to meet the altered physiological strain upon the bone resulting from the alteration in its architectural form. ”

“ The dense shadows cast by bone are, at least at present, an insuperable obstacle to skiagraphing the soft translucent organs of the body which are enclosed within a more or less complete bony case, as the rays will be intercepted by the bones. Efforts, therefore, to skiagraph the heart, the lungs, the liver, and stomach, and all the pelvic organs, probably will be fruitless to a greater or less extent until our methods are improved. ”