Occipital bone

“ In adult Man the basi-occipital, exoccipitals and supra-occipital coalesce, forming the so-called occipital bone; while the basisphenoid, presphenoid, alisphenoids, orbitosphenoids and pterygoids form [483] the sphenoid bone. The roof of the skull is partly formed by the large supra-occipital and frontals, but mainly by the parietals (fig. 99, 1) , which in Man are of enormous extent. ”

“ In man the strong forward inclination of the nuchal portion of the occipital bone is considered to have a relation to the upright position. I can not see why it should not be interpreted in the same way in the fossil skull under consideration. ”

“ The massive intermaxillary bone had its posterior margin of an angular form, and into the notch thus formed there was wedged the anterior end of a long strip of plates, which expanded as they approached the occipital part of the cranium, and terminated in three irregular plates that may represent the place of the parietal and occipital bones. ”

“ 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. ”

“ 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. ”

“ Injury to occipital lobe.—Wounded at Modder River. Scalp wound in occipital region. Two days later on arrival at the Base the patient was extremely restless and in a condition of noisy delirium. The wound was explored (Mr. J. J. Day) and a vertical gutter fracture discovered 1/2 an inch above and to the left of the occipital protuberance. The gutter was 11⁄2 inch in length and finely comminuted, the dura wounded, and the left occipital lobe pulped. A number of fragments of bone (one lodged in the wall of, but not penetrating, the lateral sinus) and pulped brain were removed. ”

“ Every one who is acquainted with the pliable condition of the cranial bones at birth, will readily conceive how effectually this apparatus would mould the head in the elongated or cylindrical form; for, while it prevents the forehead from rising, and the sides of the head from expanding, it allows the occipital region an entire freedom of growth ”

“ 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] . ”

“ The parietals and frontals, being membrane bones, are not comparable to the supra-occipital, in the way that the presphenoid and basisphenoid are to the basi-occipital. [20]
The cartilage bones of the occipital segments are derived from the parachordals of the embryonic skull, those of the parietal and frontal segments from the trabeculae. ”

“ As a rule the whole thickness of the skull is broken, and, as usual, the inner table suffers most. In infants the bones may be merely indented, the fracture being of the greenstick variety. All degrees of severity are met with, from a simple, localised indentation of the bone, to complete smashing of the skull into fragments. ”

“ If death was not too soon the consequence of the puncture of the head of hydrocephalic patients, I am persuaded that we should see the bones gradually contract, and restore the cavity of the cranium to its natural dimensions. When we remove the dead piece from a long bone in necrosis, the new bone, formed on the exterior by means of the periosteum contracts in an evident manner. In paralysis of the optic nerve, its foramen becomes narrower. The orbit contracts when a cancerous eye has been extirpated. ”

“ The disorder of growth is confined to those elements of the skeleton where a core of bone formed in cartilage comes to be encased in a sheath of bone formed beneath the periosteum. To indicate this abnormality the name _diaphysial aclasis_ has been employed by Arthur Keith at the suggestion of Morley Roberts.
Bones formed entirely in cartilage are exempt, namely, the tarsal and carpal bones, the epiphyses of the long bones, the sternum, and the bodies of the vertebrae. Bones formed entirely in membrane, that is, those of the face and of the cranial vault, are also exempt. ”

“ 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. ”

“ 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. ”