出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/03/04 10:59:11」(JST)
| Thyroid ima artery | |
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The veins of the thyroid gland (thyroid ima artery not labeled, but region is visible)
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| Details | |
| Source | Brachiocephalic, others |
| Supplies | Thyroid gland, trachea, parathyroid glands, thymus gland (as thymica accessoria) |
| Identifiers | |
| Latin | Arteria thyreoidea ima |
| Dorlands /Elsevier |
a_61/12156370 |
| TA | A12.2.04.005 |
| FMA | 3936 |
| Anatomical terminology [edit on Wikidata]
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The thyroid ima artery (thyroidea ima artery, thyroid artery of Neubauer or the lowest thyroid artery) is an anatomical variant that, when present, supplies blood to the thyroid gland, which is primarily supplied by the inferior and superior thyroid arteries. The artery also supplies the trachea, and the parathyroid gland in rare cases. The artery has also been reported to be the only source of blood to the thyroid gland or as a compensatory artery. The artery mostly arises from the brachiocephalic trunk, though it may also originate from other sources. It also varies in size, blood supply, and termination. The artery occurs in only 3–10% of the population and because of the variations, it may cause surgical complications such as severe bleeding.
The artery is an embryonic artery and it occurs because of the failure of the vessel to close, remaining patent.[1] It is postulated that the thyroid ima artery was originally a part of the vascular network that connected the brachiocephalic, aortic and carotid arteries.[2]
The artery has a variable origin. It mostly arises from the brachiocephalic trunk,[3] but may also originate from the arch of aorta, the right common carotid, the subclavian, the pericardiacophrenic artery, the thyrocervical trunk, the transverse scapular or the internal thoracic artery.[4] It ascends in front of the trachea in the superior mediastinum to the lower part of the thyroid gland.[1]
It differs in size and ranges from as small as accessory thyroid arteries to the size of primary thyroid vessels. The diameter of the lumen of the artery ranges from 3–5 millimetres (0.12–0.20 in).[5] The artery may be present as an accessory thyroid artery but sometimes appears to compensate for incompetence or absence of one or more main thyroid vessels.[6] Since it begins from below the thyroid gland and ascends upwards, it is mostly associated with absence or reduced size of the inferior thyroid arteries.[7] In such cases, it is known as the accessory inferior thyroid artery.[5][6] In rare cases, the artery has been seen to be compensating for absence of one or both superior thyroid arteries.[8]
In cases where the length of the thyroid ima artery is shorter, the artery ends by supplying the thymus gland and is known as thymica accessoria.[5]
When present, the thyroid ima's chief supply is the thyroid gland, though it also supplies the trachea. The artery may extend and supply the parathyroid glands. An infrequently observed artery, it is more frequently reported in the context of enlarged parathyroid glands (parathyroid adenomas). The artery ends by supplying the thyroid gland, or the parathyroid glands, as a single unit or as multiple branches.[6][9] The artery is also found to be the only supply of the parathyroid gland in rare cases.[6]
The artery is only present in approximately 3–10% of the population.[10][11] Thyroid ima artery is of surgical importance; due to its relatively small size and infrequent presence it can cause complications in surgery of the thorax, trachea, thyroid or parathyroid glands.[12] Knowledge of occurrence of the artery is especially important during tracheostomy and thyroidectomy.[5] Because the artery is smaller than the other thyroid vessels, and having an origin from one of the bigger vessels, a brisk cut while performing the surgery may cause complications such as severe hemorrhage and significant blood loss.[12][13] The artery, if dissected, may draw back into the mediastinum and further complicate the condition by causing hemorrhage and clots in the thoracic cavity.[14]
The thyroid ima artery was first defined by German anatomist Johann E. Neubauer in the year 1772. Hence, it was named the thyroid artery of Neubauer.[15] The artery originates lower than the inferior thyroid arteries, so it is also known as the lowest thyroid artery.[10][11]
Arteria thyreoidea ima is the Latin name of the artery.[11][3]
The presence of thyroid ima artery is also observed in other higher primates. The artery has been reported in gorillas, gibbons, macaques and gray langurs. Variations in the origin were also seen; it was found to originate from the aorta in the thorax, or the carotid in the neck.[16]
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| リンク元 | 「最下甲状腺動脈」 |
| 関連記事 | 「thyroid」「IMA」 |