Z8600021: /* The thyroid gland and its relations */

2013-02-25T21:48:49Z

The thyroid gland and its relations

← Older revision		Revision as of 08:48, 26 February 2013
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	Small detached portions of thyroid tissue are sometimes found in the vicinity of the lateral lobes or above the isthmus; they are called accessory thyroid glands (glandulæ thyreoideæ accessoriæ).		Small detached portions of thyroid tissue are sometimes found in the vicinity of the lateral lobes or above the isthmus; they are called accessory thyroid glands (glandulæ thyreoideæ accessoriæ).



			:'''Links:''' '''Bold text'''[[Endocrine_-_Thyroid_Development\|Thyroid Development]] \| [[Endocrine_System_Development\|Endocrine Development]]

Z8600021 at 02:19, 25 February 2013

2013-02-25T02:19:46Z

← Older revision		Revision as of 13:19, 25 February 2013
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	==The thyroid gland and its relations==		==The thyroid gland and its relations==

			The Thyroid Gland (Glandula Thyreiodea; Thyroid Body) (Fig. 1174).—The thyroid gland is a highly vascular organ, situated at the front and sides of the neck; it consists of right and left lobes connected across the middle line by a narrow portion, the isthmus. Its weight is somewhat variable, but is usually about 30 grams. It is slightly heavier in the female, in whom it becomes enlarged during menstruation and pregnancy.


			The lobes (lobuli gl. thyreoideæ) are conical in shape, the apex of each being directed upward and lateralward as far as the junction of the middle with the lower third of the thyroid cartilage; the base looks downward, and is on a level with the fifth or sixth tracheal ring. Each lobe is about 5 cm. long; its greatest width is about 3 cm., and its thickness about 2 cm. The lateral or superficial surface is convex, and covered by the skin, the superficial and deep fasciæ, the Sternocleidomastoideus, the superior belly of the Omohyoideus, the Sternohyoideus and Sternothyreoideus, and beneath the last muscle by the pretracheal layer of the deep fascia, which forms a capsule for the gland. The deep or medial surface is moulded over the underlying structures, viz., the thyroid and cricoid cartilages, the trachea, the Constrictor pharyngis inferior and posterior part of the Cricothyreoideus, the esophagus (particularly on the left side of the neck), the superior and inferior thyroid arteries, and the recurrent nerves. The anterior border is thin, and inclines obliquely from above downward toward the middle line of the neck, while the posterior border is thick and overlaps the common carotid artery, and, as a rule, the parathyroids.


			The isthmus (isthmus gl. thyreoidea) connects together the lower thirds of the lobes; it measures about 1.25 cm. in breadth, and the same in depth, and usually covers the second and third rings of the trachea. Its situation and size present, however, many variations. In the middle line of the neck it is covered by the skin and fascia, and close to the middle line, on either side, by the Sternothyreoideus. Across its upper border runs an anastomotic branch uniting the two superior thyroid arteries; at its lower border are the inferior thyroid veins. Sometimes the isthmus is altogether wanting.


			A third lobe, of conical shape, called the pyramidal lobe, frequently arises from the upper part of the isthmus, or from the adjacent portion of either lobe, but most commonly the left, and ascends as far as the hyoid bone. It is occasionally quite detached, or may be divided into two or more parts.


			A fibrous or muscular band is sometimes found attached, above, to the body of the hyoid bone, and below to the isthmus of the gland, or its pyramidal lobe. When muscular, it is termed the Levator glandulæ thyreoideæ.


			Small detached portions of thyroid tissue are sometimes found in the vicinity of the lateral lobes or above the isthmus; they are called accessory thyroid glands (glandulæ thyreoideæ accessoriæ).

Z8600021: ==The thyroid gland and its relations== {{Gray Anatomy}} Category:Human Category:Thyroid Category:Cardiovascular

2013-02-25T02:13:21Z

==The thyroid gland and its relations== {{Gray Anatomy}} Category:Human Category:Thyroid Category:Cardiovascular

New page

==The thyroid gland and its relations==

{{Gray Anatomy}}

[[Category:Human]] [[Category:Thyroid]] [[Category:Cardiovascular]]

File:Gray1174.jpg - Revision history

Z8600021: /* The thyroid gland and its relations */

Z8600021 at 02:19, 25 February 2013

Z8600021: ==The thyroid gland and its relations== {{Gray Anatomy}} Category:Human Category:Thyroid Category:Cardiovascular