Thyroid cartilage

“ It opens into the membrane which connects these structures (the thyroid membrane) on the left side, and the opening can be closed by the contraction of the muscles which reach from the tongue-bone (os hyoides) to the larynx cartilage (thyroid cartilage—the thyro-hyoid muscles) . ”

“ The precise locality at which the common carotid appears from under the sterno-mastoid muscle is, in almost all instances, opposite to the thyroid cartilage. At this place, if an incision, dividing the skin, platysma and some superficial branches of nerves, be made along the anterior border of the sterno-mastoid muscle, and this latter be turned a little aside, a process of cervical fascia, and beneath it the sheath of the carotid artery, will successionally disclose themselves. ”

“ The thyroid cartilage is probably formed from the fourth and fifth bronchial bars, while the cricoid seems to be the enlarged first ring of the trachea. Before birth the lungs are solid and much less vascular than after breathing is established. Their slaty colour is gradually gained from the deposit of carbon from the atmosphere. ”

“ Hyaline cartilage.—Specimens may be obtained from any joint, from the costal cartilages of young animals, or from the thyroid cartilage and tracheal rings. It may be hardened in spirit. Stain with picrocarmine, eosine and hæmatoxyline, and with methyl violet. ”

“ Cut throat wounds, when suicidal and inflicted by the right hand, are generally oblique from left to right, beginning higher up than they end. They generally cross the thyroid cartilage, and the larger vessels may escape; if made below the thyroid cartilage they are generally smaller and horizontal. ”

“ In many of the lower mammals (e.g. Ungulata and Carnivora) the hyoid arch is much more completely ossified than it is in man, tympano-, stylo-, epi-. cerato- and basihyal elements all being bony (see fig. 34) . It is of interest to notice that in the hares and rabbits the body of the hyoid has occasionally been found in two pieces, indicating its derivation from the second and third visceral arches. The fourth and fifth arches, which form the thyroid cartilage in mammals, are considered in the article Respiratory System. ”

“ CRETINISM AS THYROID DEFICIENCY Not that there is any arresting contrast of startling difference between the phenomena presented by different species. The younger the animal, the grosser the morbid symptoms witnessed. The animal fails to grow. The bones and cartilage, except of the skull, fail to develop. The abdomen projects and becomes large and flabby. The sex organs atrophy. There is sterility. Pregnant rabbits abort, hens produce very small eggs or none at all. These are the results of removing the thyroid in animals. ”

“ The elevator and depressor muscles draw the trachea and larynx up and down with a rapidity and a force which may bring the cricoid cartilage within half an inch of the sternum. The great thyroid veins which descend in front of the trachea are sure to be distended. There may be a middle thyroid artery. In children the lobes of the thymus may extend up in front of the trachea, and the left vena innominata may cross it unusually high. ”

“ The influence of the thyroid upon the skeleton and size of the body is easily shown by simple observations.
Children of parents with cachectic diseases like chronic tuberculosis, syphilis, alcoholism, etc., in which the thyroid gland is, as a rule, found degenerated (Gamier, [31] Hertoghe [32] ) , are (as shown by Prof. Perrando [33] and Garnier) born with a congenital atrophy of the thyroid. Just as young animals with an extirpated 14thyroid, so these children will not grow, and we know that cretins (degeneration of the thyroid) remain as a rule dwarfs all their life long. ”

“ Pulsation of their arteries is apparent to the hand and to the eye. A systolic arterial blowing murmur and a continuous hum are heard when the thyroid region is auscultated. In some instances the murmur is like that of an aneurismal varix. As a rule, murmurs are heard over the carotid artery and the jugular vein. A thrill or fremitus is often felt by the hand placed upon the thyroid body. The thyroid enlargement is due at first chiefly to dilatation of the arteries and veins. Hyperplasia of the fibroid tissue occurs afterward, and then the enlarged gland becomes hard to the touch. ”

“ A small artery sometimes forms, with its fellow of the opposite side, a transverse communication across this membrane, and its presence has been much insisted on as a circumstance of practical importance: it is of extreme minuteness, and by no means constantly present: it is the crico-thyroid, and arises from the thyroid branch of the external carotid, near the upper angle of the thyroid body, and runs across the membrane toward the median line. ”

“ On the post-mortem examination, the course of the ball was found as stated above, viz., it had run from the integuments to the body of the sixth cervical vertebra, leaving the trachea and œsophagus internally, and the carotid sheath and its contents externally, untouched. The inferior thyroid artery was wounded just before it reaches the thyroid gland, and had a firm clot, about half an inch in length, filling its cylinder. The transverse process of the sixth cervical vertebra was fractured, and had left the wounded vertebral artery unprotected. ”

“ Occasionally, from the top of the isthmus, a nearly but not quite median pyramidal lobe runs up toward the hyoid bone, while in other cases the isthmus may be absent. The gland is relatively larger in women and 635 children than in the adult male. It is enclosed in a capsule of cervical fascia and is supplied by the superior and inferior thyroid arteries on each side, though occasionally a median thyroidea ima artery is present. ”

“ It is found in various parts of the body, in the adults being found chiefly in the joints, in the sides of the thorax, and in various tubes which are not kept permanently open, such as the air passages, nostrils, ears, etc. In the foetus, the greater part of the framework is cartilaginous and as the foetus matures this cartilage is finally replaced by bone. Cartilage is divided into hyaline cartilage, elastic cartilage, and fibro cartilage.
Hyaline cartilage is found in the nose, larynx, trachea, and bronchi. ”

“ Thyroid internal secretion has a very definite controlling relation to all of them: to skin, its hairiness, moisture and amount of mucus, to the growth and size of the bones, especially the bones of the extremities and the skull, and to intelligence and the complexity of the convolutions of the brain. Injury to the thyroid, especially in growing animals, is followed by profound retrogression or arrest of development in skin, skeleton and brain. ”

“ Those things which we know as bony elements of the skeleton in the adult, in the embryo exist merely as cartilage, but the cartilage is not converted into bone but it is destroyed and its place taken by bone. There is overlying the heart of a child at birth a well-developed gland known as the thymus. After childhood this undergoes a retrograde development ”

“ Goiter is endemic in some countries, particularly in Switzerland and Austria, and appears particularly at the age of childhood or of puberty. Some communities in this country using water containing an excess of calcium salt show distinct evidences of endemic goiter. Extirpation of the thyroid gland has in recent years been successfully practiced. Warren has extirpated one lobe of the thyroid after preliminary ligation of the common carotid on the same side. Green practiced rapid removal of the tumor and ligated the bleeding vessels later. ”

“ The _ankylosing type_ of chronic arthritis is fortunately much rarer than those described above, and is chiefly met with in the joints of the fingers and toes and in those of the vertebral column. The synovial membrane proliferates, grows over the cartilage, and replaces it, and when two such articular surfaces are in contact they tend to adhere, thus obliterating the joint, cavity, and resulting in fibrous or bony ankylosis. ”

“ In a Scyllium embryo belonging to the early part of stage K, the thyroid gland presented the same arrangement as in the Torpedo embryo just described, with the exception that no solid posterior section of it was present.
Towards the close of stage K the thyroid body begins to elongate and become solid, though it still retains its attachment to the wall of the œsophagus. The solidification is effected by the columnar cells which line the groove elongating and meeting in the centre. ”

“ The next section caudad to this shows the thyroid as a round, compact mass of cells, with a very small lumen, still closely fused with the bottom of the oral groove. The lumen may, in this embryo, be traced for only a few sections, caudad to which the thyroid is seen as a small, solid mass of cells unattached to the oral groove. Close to the sides of the thyroid are seen two large blood vessels, ar, the mandibular arches, which unite into the single ventral aorta just caudad to the posterior end of the thyroid. ”

“ It is obvious that, when the disease has proceeded thus far, the joint must become more or less deformed, and its motions considerably impeded. Accordingly, old men are often seen at work with much rigidity of the joints, particularly of the knee, which is frequently projected inwards, from absorption of the cartilage from the outer condyle of the femur and corresponding part of the tibia, with a thinning and degeneration of the inner-articular cartilage into a tissue resembling the cellular. ”

“ The operators at first thought they were mistaken in supposing that they had tied the vertebral artery, as the vessel seemed quite free, while it is known to be protected by the transverse processes in that locality, and believed they had secured the inferior thyroid. The hemorrhage ceased at once, and some smaller vessels were then tied, among which was the inferior thyroid artery. ”

“ Following the increased frequency of the heart's action, after a variable period enlargement of the thyroid body occurs. The enlargement may be rapid, but in most cases it takes place slowly, and ceases when it has reached a moderate degree. Cases are exceptional in which the degree of enlargement is such as to occasion any obstruction to respiration. Almost invariably both lobes of the thyroid body are enlarged, but the enlargement is generally not equal on the two sides, and, as a rule, it is greater on the right side. The enlarged lobes are soft at first, afterward becoming hard. ”

“ In young adolescents it may be so rapid that the patient has to be kept lying down to prevent permanent bending of the long bones of the leg, softened by their rapid growth. A very typical case under Dr Hector Mackenzie, showing what can be expected from early treatment, is that of a cretin aged 11 years in 1893, when thyroid treatment was started. ”

“ The destruction of cartilage may be secondary to disease of the synovial membrane or of the subjacent bone. When the disease begins as a synovitis, the synovial membrane spreads over the articular surface, fuses with the cartilage and eats into it, causing defects or holes which are spoken of as ulcers. When the disease begins in the bone, the marrow is converted into granulation tissue, which eats into the cartilage and separates it from the bone. ”

“ As a rule these attacks are repeated; the pain attending them diminishes, but the joint becomes the seat of permanent changes: the synovial membrane is thickened, abnormally vascular, and coloured brown from the deposit of blood pigment; on its surface, and in parts of the articular cartilage, there is a deposit of rust-coloured fibrin; there may be extensive adhesions, and in some cases changes occur like those observed in arthritis deformans with erosion and ulceration of the cartilage and a form of dry caries of the articular surfaces, which may terminate in ankylosis. ”

“ The morbid process in the articular ends in rheumatoid arthritis is one of rarefaction and softening. The cartilage may undergo total or partial absorption, a change to be detected in the very early stages. The bones participate in the pathological change, the first evidence of which is an abnormal translucency to the rays, usually, but not always, confined to that portion of the shaft entering into the joint. ”

“ Dohrn rightly separates the median ciliated groove posterior to the thyroid orifice (seen in Fig. 81 (6) ) from the paired pseudo-branchial grooves; the former is a shallow depression which opens into the rim of the thyroid orifice, while the latter has a much more intimate connection with the thyroid gland itself. ”

“ The thyroid bears more directly upon the inner and outer coverings of the body, the skin, the skin glands and the hair, the mucous membranes, and the irritability and the preparedness for response of the nerves. The pituitary acts more upon the framework of the body, the skeleton and the mechanical supports and movers. Bone and ligament, muscle and tendon seem to be within its immediate sway. The secretion or secretions of the pituitary diffuse directly into the fluid bathing the nervous system, supplying beneficent stimulants and aiding in the abstraction of harmful waste. ”

“ The pulse-rate becomes very rapid, the extremities become warm, so that the patient is obliged to wear few clothes, the temper becomes irritable, the patient nervous, and a fine tremor is observed in the hands. On stopping the administration of thyroid these symptoms again disappear. When the thyroid is hypertrophied, as in Graves's disease, the same symptoms are observed, and these are probably due to increased secretion from the thyroid. At the same time other symptoms, such as exophthalmos, may appear, which have an independent origin and are not due to the secretion of the gland. ”