a. (sb.) Also 9 thyreoid (in Dicts.). [Etymologically thyreoid, ad. Gr. θυρεοειδής shield-shaped (in Galen χόνδρος θυρεοειδής thyroid cartilage), f. θυρεό-ς oblong shield + -ειδής: see -OID. Cf. obs. F. thyroide (Paré, 16th c.), mod. F. thyréoïde.] Having the form of a shield, shield-shaped: applied to various natural structures (and hence transf. to others connected with them).
1. Anat. a. Thyroid cartilage: the largest of the cartilages of the larynx, consisting of two broad quadrilateral plates united in front at an angle, forming the projection in front of the throat known (in men) as ‘Adam’s apple’; within the angle are attached the vocal cords.
[1693. trans. Blancard’s Phys. Dict. (ed. 2), Thyroides, the Cartilage, called Scutiformis, of the Larynx.]
1726–45. Monro, Anat. (ed. 3), 163. Into this Concavity the Thyroid Cartilage is received.
1808. Barclay, Muscular Motions, 498. The larynx is partly composed of five cartilages, which are the cricoid, thyroid, the two arytænoid, and the epiglottis.
1854. Bushnan, in Orr’s Circ. Sc., I. Org. Nat., 121. The thyroid cartilage is wrapped round the essential parts of the larynx.
1857. Dunglison, Med. Lex., Thyroid, Thyreoid.
b. Thyroid gland (also called thyroid body): one of the so-called ‘ductless glands,’ a very vascular body adjacent to the larynx and upper part of the trachea in vertebrates.
[1693. trans. Blancard’s Phys. Dict. (ed. 2), Thyroideæ Giardulæ, two, of a viscous … Substance,… situate about the lower seat of the Larynx].
1726–41. Monro, Anat. (ed. 3), 163. The lymphatic Vessel is … sent from the thyroid Gland.
1727–41. Chambers, Cycl., s.v. Thymus, Mr. Cheselden observes, that where the thymus in men is very small, the thyroid glands increase proportionably.
1830. R. Knox, Béclard’s Anat., 240. Formless fibro-cartilages occur in some compound tumours of the thyroid body.
1872. Huxley, Phys., v. 126. The thyroid gland … is that organ which when enlarged by disease gives rise to ‘Derbyshire neck’ or ‘goitre.’
1899. L. Hill, Man. Hum. Physiol., xxvi. 301. If a cretin be fed on thyroid glands taken from sheep his condition is improved…. It is clear then that the thyroid gland produces a material necessary for the growth of the body.
c. Applied to various structures connected with the thyroid cartilage or gland, as the thyroid arteries, nerves, veins, etc. Thyroid axis, a branch of the subclavian artery, distributed to the thyroid gland and adjacent parts. (See also B. 2 b.)
1831. R. Knox, Cloquet’s Anat., 746. Right Inferior Thyroid Vein … similar to the left, with which it constitutes the thyroid venous plexus.
1840. E. Wilson, Anat. Vade M. (1842), 271. The Superior Thyroid Artery curves downwards to the thyroid gland to which it is distributed.
1878. T. Bryant, Pract. Surg., I. 104. Thyroid cysts may be tapped in the same way as the cervical.
1881. Mivart, Cat, 209. The second branch given off from the subclavian … is the thyroid axis.
d. Thyroid foramen, membrane: names for the obturator foramen and membrane of the hip-bone (see OBTURATOR 1), from their shield-like shape.
1890. Billings, Nat. Med. Dict., T[hyroid]foramen, obturator foramen.
2. Zool. Applied to a shield-shaped color-marking, or transf. to a bird having such a marking, as the thyroid woodpecker, Sphyropicus thyroideus.
1891. in Cent. Dict.
3. Bot. ‘Shield-like, peltiform.’
1900. in B. D. Jackson, Gloss. Bot. Terms, 270/2.
B. as sb. 1. Short for thyroid cartilage.
1840. E. Wilson, Anat. Vade M. (1842), 492. The Thyroid is the largest cartilage of the larynx.
1854. Owen, Skel. & Teeth, in Orr’s Circ. Sc., I. Org. Nat., 210. Extending beyond and sustaining the thyroid and other parts of the larynx. Ibid. (1868), Vertebr. Anim., xxxiii. III. 603. Castration arrests that prominent growth of the thyroid, &c., which accompanies the elongation of the cords.
2. Short for thyroid gland; also for thyroid extract or product (see b).
1849–52. Todd’s Cycl. Anat., IV. 1102/2. The normal weight of the thyroid is about one ounce.
1897. Allbutt’s Syst. Med., IV. 469. The sheep’s thyroid is relatively rich in thyroiodine. Ibid., 476. In cases of … myxœdema the results of treatment by thyroid justify a strong expectation of cure.
1897. Trans. Amer. Pediatric Soc., IX. 65. In cretinism we are certain that the prolonged use of thyroids is followed by distinct changes in the blood.
b. attrib.
1895. Pall Mall G., 16 Dec., 1/3. The use of thyroid extract as a remedy for certain diseases … is looked upon as one of the most brilliant of recent medical discoveries.
1899. Allbutt’s Syst. Med., VIII. 68. Thyroid treatment of cases of tetany. Ibid., 673. The horny growth fell off, while the patient was under thyroid feeding.
Hence Thyroidal, Thyroideal, Thyroidean adjs., pertaining to the thyroid cartilage or gland; Thyroidectomize v., trans. to subject to thyroidectomy; Thyroidectomy [Gr. ἐκτομή a cutting out], excision of the thyroid gland; Thyroidin, trade-name of a whitish powdered extract of the thyroid gland of the sheep, used as an alterative and an anti-fat; Thyroidism, a morbid state consequent on administration of thyroid extract; thyroid poisoning; Thyroiditis, inflammation of the thyroid gland; Thyroidization, treatment with a preparation of the thyroid (Dorland); Thyroidless a., having no thyroid gland; Thyroidotomy [Gr. τομή cutting], incision of the thyroid gland.
1860. Mayne, Expos. Lex., Thyroideus,… *thyroidal: *thyroidean.
1872. Cohen, Dis. Throat, 51. The anterior portions of the vocal cords attached to the thyroidal junction.
1827. Abernethy, Surg. Wks., II. 127. The superior *thyroideal, lingual, and facial branches of the external carotid.
1854. Jones & Sieveking, Pathol. Anat. (1874), 122. Ligature of the thyroideal arteries has caused considerable diminution of a goitrous tumour.
1899. Allbutt’s Syst. Med., VIII. 57. The administration of thyroid in some form to *thyroidectomised animals or man.
1889. Buck’s Handbk. Med. Sc., VIII. 545/2. Until the middle of the eighteenth century no true *thyroidectomy … had been performed.
1891. Lancet, 18 April, 907/1. M. Reverdin … has performed thyroidectomy in this disease in fourteen cases.
1897. Allbutt’s Syst. Med., III. 314. Thyroid grafts prolong life after complete thyroidectomy.
1896. Pharmaceutical Jrnl., 5 Sept., 215. *Thyreoidin, the active principle of thyroid.
1897. Allbutt’s Syst. Med., III. 315. A non-proteid substance containing a considerable percentage of iodine—the so-called thyroidin. Ibid. (1897), II. 78. In most of them the symptoms of *thyroidism were produced.
1889. Buck’s Handbk. Med. Sc., VII. 96/1. Inflammation of the thyroid gland (*thyroiditis …) is most commonly … the … result of remedial measures employed in the treatment of goitre.
1890. Billings, Nat. Med. Dict., *Thyroidotomy.
