Navicular bone

“ When we view the relative position of the subclavian vessels, A B, Plate 11, to the clavicle, R, we can readily understand why a fracture of the middle of this bone through that arch which it forms over the vessels, should interfere with the free circulation of the blood which these vessels supply to the arm. When the clavicle is severed at its middle, the natural arch which the bone forms over the vessels and nerves is lost, and the free moving broken ends of the bone will be acted on in opposing directions by the various muscles attached to its sternal and scapular extremities. ”

“ Many other small Holes are found in divers places of the Basis of the Skull; the chief whereof are those that are observ'd in the Apophysis Petrosa, and give Passage to a great number of Vessels that serve for the Nutriment of that part of the Temporal Bone which is call'd the Tympanum, or Drum: The other Holes are principally design'd for the Vessels that are serviceable in the nourishing of divers parts of the Basis of the Skull. ”

“ The upper and lateral parts of the skull are covered by well-developed membrane bones, which, from this suborder, upwards in the series, will be found to exist throughout the remaining forms of fishes. They are bones, the origin of which is not in cartilage but in membranous connective tissue. The lower surface of the skull is covered by an extremely large basal bone, which extends from the vomerine region on to the anterior part of the spinal column. The nasal excavation in the skull is rather lateral than inferior. ”

“ In the section on osteology it has been explained how, in living cetaceans, the entire skeleton is loosely articulated so that great flexibility and freedom of movement is given to the body, how the neck 321is shortened and the vertebræ have become thin and closely packed together to support the large head, and how the breast bone is reduced and the ribs so loosely articulated to the vertebral column that the huge lungs have full power of expansion. ”

“ In the chimæra the mandible is articulated directly with the skull, the hyomandibular and quadrate elements being fused with the cranium. The skull in such case is said to be autostylic, that is, with self-attached mandible. In the shark it is said to be hyostylic, the hyomandibular intervening. The upper jaw in the shark consists not of maxillary and premaxillary but of palatine elements, and the two halves of the lower jaw are representatives of Meckel's cartilage, which is the cartilaginous centre of the dentary bone in the bony fishes. ”

“ 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. ”

“ In Fishes.—Bony fishes, and all others in which separate bones build up the skull, differ from Reptiles and Birds much as those animals differ from Mammals. The union of the lower jaw with the skull becomes complicated by the presence of additional bones. The quadrate bone still forms a pulley articulation upon which the lower jaw works, but between it and the squamosal bone is the characteristic bone of the fish known as the hyomandibular, commonly connected with opercular bones and metapterygoid which intervene, and help to unite the quadrate with the brain case. ”

“ The possession of a backbone or bony (sometimes cartilaginous) spinal column is the characteristic by which we distinguish them from the invertebrate or backboneless animals. Furthermore, all of the vertebrates possess an internal skeleton which is in most cases composed of bone, and is firm and strong. In some of the lower fishes, as the sharks and sturgeons, the skeleton is made up of cartilage, tough but not hard. ”

“ When the mouth is opened, their elasticity causes them to straighten out like a bow unbent, so that at whatever distance the jaws are separated the strainer remains in perfect action, filling the whole of the interval. The mechanical perfection of the arrangement is completed by the great development of the lower lip, which rises stiffly above the jaw-bone and prevents the long, slender, flexible ends of the whalebone from being carried outwards by the rush of water from the mouth, when its cavity is being diminished by the closure of the jaws and raising of the tongue. ”

“ But in the case of the true Placoids that analogy is faint indeed. Their skeletons contain true bone;—the vertebral joints of the Sharks and Rays possess each, as has been shown, an osseous nucleus, which retains, when subjected to the heat of a common fire, the complete form of the joint; and their cranial framework has its surface always covered over with hard osseous points. But though their skeletons possess thus their modicum of bone, unlike those of embryonic birds or mammals, they contain, in what is properly their cartilage, no gelatine. ”

“ The lachrymal (3) is a fairly large bone that forms the anterior border of the orbit. It is bounded laterally by the jugal, anteriorly by the maxilla, and medially by the prefrontals. Its postero-medial border is pierced by a large lachrymal foramen that extends lengthwise through the bone and opens, at its anterior end, into the nasal chamber.
The supraorbital, missing in the skull figured, is a small bone lying in the eyelid close to the junction of the frontal and prefrontal. Being unattached it is usually absent from prepared skulls. ”

“ It consists of two layers, an outer fibrous and an inner cellular layer; the cells, which are called osteoblasts, are continuous with those lining the Haversian canals and the medullary cavity.
The arrangement of the blood vessels determines to some extent the incidence of disease in bone. The nutrient artery, after entering the medullary canal through a special foramen in the cortex, bifurcates, and one main division runs towards each of the extremities, and terminates at the ossifying junction in a series of capillary loops projected against the epiphysial cartilage. ”

“ There is a great amount of variation as regards the degree in which the primordial cranium persists; it is always more or less replaced by bone; frequently it disappears entirely, but in some fishes, like the Salmonidæ or Esocidæ, the cartilage persists to the same or even to a greater extent than in the Ganoidei holostei. Added to the bones preformed in cartilage are a great number of membrane-bones. ”

“ The portion of outer osseous shell projecting into the medullary canal would in the end have been removed by the absorbents, and the deformity much diminished.
When the ends of the bone are not well placed, or when they are moved occasionally whilst the uniting medium is still soft, there is danger of a false joint being formed—the callus either giving way, or being all along imperfect, and the extremities at the soft part becoming smooth and moveable on each other; or incited action may run high and terminate in suppuration, with death or ulceration of portions of the bone. ”

“ Dorsal fin low, rather behind the middle of the back. Pectoral fins ovate, elongate. Skull depressed, with the lateral expansions horizontal, rather thickened and bent up over the orbit and slightly dilated and bent down over the notch. Intermaxillaries dilated, swollen in front of the blower. Atlas free; rest of cervical vertebræ and dorsal processes united. The arm-bones short. Two middle fingers elongated, subequal, of eight or nine phalanges; the other fingers very short, of two or three phalanges. The breast-bone single, broad in front.
1. GRAMPUS. ”

“ Like the crocodiles, birds possess a siphonium, i.e. a membranous, or ossified, tube which rises from a pneumatic foramen in the os articulare, on the median side of the articulation, and passes upwards between the quadrate and lateral occipital bone, opening into the cavity of the middle ear. ”

“ They exhibit a rough symmetry; they rarely attain any size; and they usually cease growing when the skeleton attains maturity—the conversion of cartilage into bone being then completed. While they originate from the ossifying junctions of the long bones, they tend, as the shaft increases in length, to project from the surface of the bone at some distance from the ossifying junction and to “point” away from it. They may cause symptoms by “locking” the adjacent joint or by pressing upon nerve-trunks or blood vessels. ”

“ If, on the contrary, there is much displacement, and if that is not entirely removed, intense action ensues both in the soft and hard parts, there is great effusion of new matter, or callus, soft and yielding at first, but gradually becoming hard and dense—bony particles being deposited from the vessels ramifying in the extremities, or in the attached fragments, of the old bone. When detached portions of callus are found lying in the soft parts, a piece of old bone which retained its vitality has generally formed the matrix of the deposit. ”

“ 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. ”

“ Most of the larger scutes and the upper surface of the bones of the skull have a peculiar gnawed-out, almost honeycombed appearance, as is usual wherever most of the cutis itself is transformed into bone or co-ossifies with underlying bone, while the uppermost layers and the horny layer of the epidermis are much reduced and thinned out. ”

“ When the backbone has been chopped nearly through, a jerk of the tackle breaks the remainder, and the head is then hauled on deck. As a large whale's head frequently contains several thousand dollars worth of bone, the suspense and [Pg 267] anxiety of the whaler while it is being taken off can be readily understood. When the head has been secured, the work of taking off the remainder of the blubber is resumed. Some vessels save only the bone, and cast the body adrift after the head has been cut off, but these are usually ships without the needed apparatus for trying out the oil. ”

“ The jaw-bone of a fish furnished with teeth would be more proper; but the words spina in medio pisce prevent us from adopting that alteration. I should be inclined rather to explain this difficulty by the bone which projects from the snout of the saw-fish, called by the Romans serra, and by the Greeks pristis. That bone, indeed, might not be altogether unfit for such a use: the teeth are strongly united to the broad bone in the middle, and are capable of resisting a great force; but they are placed at rather too great a distance. ”

“ The inner shell of bone, as may be seen in the above sketch, perishes more extensively than the outer; and this arises probably from inflammation of the medullary membrane, in consequence of exposure, or, perhaps, from its being sometimes injured by the operator or assistants seizing the bone rudely to steady the stump, in order to facilitate the ligature of the vessels. In experiments on animals, the disturbance and injury of the medullary membrane is followed by internal necrosis, thickening of the outer living shell, and effusion betwixt the periosteum and bone. ”

“ The nasal process for articulation with the frontal and nasal bones has, at its lower edge, a crest for the inferior turbinated bone, and close beside this on the inside, extending down from the upper edge, is a deep groove which, with the lachrymal and inferior turbinated bones, helps to form the lachrymal canal for the nasal tear duct. The bones give attachment to many small muscles, connected for the most part with the nose and mouth, of which the masseter is the only important one. ”

“ A woman expert at this business will perform it very quickly and with great regularity, but seldom without drawing blood in many places, and occasioning some inflammation. Where so large a portion of the surface of the body is to be covered, it must become a painful as well as tedious process, especially as, for want of needles, they often use a strip of whalebone as a substitute. For those parts where a needle cannot conveniently be passed under the skin, they use the method by puncture, which is common in other countries, and by which our seamen frequently mark their hands and arms. ”

“ Now, I consider that the phrenologists have omitted an important thing in not pushing their investigations from the cerebellum through the spinal canal. For I believe that much of a man’s character will be found betokened in his backbone. I would rather feel your spine than your skull, whoever you are. A thin joist of a spine never yet upheld a full and noble soul. I rejoice in my spine, as in the firm audacious staff of that flag which I fling half out to the world.
Apply this spinal branch of phrenology to the Sperm Whale. His cranial cavity is continuous with the first neck-vertebra ”

“ In the cod, as in most other osseous fishes, the upper portion of the cranium consists of thirteen bones, which represent, however, only seven bones in the human skull,—the nasal, the frontal, the two parietal, the occipital, and one-half the two temporal bones. And whereas in man, and in most of the mammals, there are four of these placed in the medial line,—the four which, according to the assertors of the vertebral theory, form the spinal crests of the four cerebral vertebræ,—in the cod there are but [72] three. ”