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The pyramidal lobe is a remnant of the thyroglossal duct, which usually wastes away during the thyroid gland's descent. [5] Small accessory thyroid glands may in fact occur anywhere along the thyroglossal duct, from the foramen cecum of the tongue to the position of the thyroid in the adult. [4]
The hypothalamic–pituitary–thyroid axis (HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine system responsible for the regulation of metabolism and also responds to stress. As its name suggests, it depends upon the hypothalamus, the pituitary gland, and the thyroid gland.
Thyroid follicular cells form a simple cuboidal epithelium and are arranged in spherical thyroid follicles surrounding a fluid filled space known as the colloid. The interior space formed by the follicular cells is known as the follicular lumen .
The thyroid cartilage is a hyaline cartilage structure that sits in front of the larynx and above the thyroid gland. The cartilage is composed of two halves, which meet in the middle at a peak called the laryngeal prominence, also called the Adam's apple. [1] In the midline above the prominence is the superior thyroid notch.
This inferior end of the duct will then become the pyramidal lobe of the thyroid gland. The dividing cellular cords of the tubular duct become the isthmus and lateral lobes of the gland to complete the formation of the rest of the gland. [5] Once the thyroglossal duct involutes, the cells will begin to degenerate and disappear.
During embryonic development, the thyroid gland is being formed, beginning at the base of the tongue and moving towards the neck canal, known as the thyroglossal duct. Once the thyroid reaches its final position in the neck, the duct normally disappears. In some individuals, portions of the duct remain behind, leaving small pockets, known as cysts.
After enveloping the thyroid gland, it is prolonged in front of the trachea to meet the corresponding layer of the opposite side. The pretracheal layer of the deep cervical fascia passes in front of the carotid sheath (i.e., common carotid artery , internal jugular vein , and vagus nerve ) and in front of the cervical viscera ( larynx ...
The middle thyroid vein (Latin: vena thyreoidea media) collects the blood from the lower portion of the thyroid gland. It receives tributaries that drain the larynx , and trachea . It passes anterior to the common carotid artery to reach and drain into the internal jugular vein .