Page 1 of 2: true or false- thyroid with explanation

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

Regarding the embryology of the thyroid gland

A. the thyroid develops from ventral pharyngeal gut endoderm.
B. this development occurs in the 4th week of intrauterine life.
C. the embryonic thyroid descends from the foramen caecum, situated in the anterior part of the tongue.
D. The thyroid usually reaches the front of the trachea by the 5th month of intrauterine life.
E. the thyroglossal duct is originally a hollow tube running from foramen caecum to pharynx.
F. thyroglossal duct tissue normally becomes solid and remains uncanalised after transit of the thyroid.
G. The pyramidal lobe of the thyroid represents part of the thyroglossal duct. T

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

answers are

1. Regarding the embryology of the thyroid gland:
A. the thyroid develops from ventral pharyngeal gut endoderm. T
B. this development occurs in the 4th week of intrauterine life. T
C. the embryonic thyroid descends from the foramen caecum, situated in the anterior part of the tongue. F
D. The thyroid usually reaches the front of the trachea by the 5th month of intrauterine life. F
E. the thyroglossal duct is originally a hollow tube running from foramen caecum to pharynx. F
F. thyroglossal duct tissue normally becomes solid and remains uncanalised after transit of the thyroid. F
G. The pyramidal lobe of the thyroid represents part of the thyroglossal duct. T

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

explanation

The foramen caecum is described as being in the posterior part of the tongue; although, strictly speaking, it marks the junction of the anterior 2/3 and posterior 1/3. The thyroid begins its development in the 1st month, and completes its descent to (usually) the front of the trachea by the end of the 2nd month IUL. The hollow thyroglossal duct does become solid after transit of the thryoid, but then usually breaks apart and disappears shortly after. In addition to the commonly found pyramidal lobe, any remnant ductal epithelium from the thyroglossal duct could potentially give rise to a thyroglossal cyst.

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

please add more such entries . don't u think this is also a good way to remember the things easily

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

3. The lateral thyroid anlagen:
A. are part of the parathyroid gland.
B. arise from the 4th pharyngeal pouch.
C. fuse to the posterior and medial aspect of the main gland.
D. correspond to the ultimobranchial bodies.
E. contain parafollicular cells which produce parathyroid hormone.
F. can give rise to medullary carcinoma.

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

3. The lateral thyroid anlagen:
A. are part of the parathyroid gland. F
B. arise from the 4th pharyngeal pouch. T
C. fuse to the posterior and medial aspect of the main gland. T
D. correspond to the ultimobranchial bodies. T
E. contain parafollicular cells which produce parathyroid hormone. F
F. can give rise to medullary carcinoma. T

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

explanation

The lateral thyroid anlagen correspond to the ultimobranchial bodies, and contain the parafollicular cells (C cells) which produce the hormone calcitonin. These anlagen comprise only 1% of the thyroid, but are the cells that may give rise to medullary thyroid carcinoma.

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

4. Regarding the vascular supply to the thyroid gland:
A. It comes primarily from the superior and inferior thyroid arteries.
B. The origin of the inferior thyroid artery is more constant than the superior.
C. Small branches from the laryngeal and tracheo-oesophageal arteries also supply thyroid tissue.
D. When the thyroidea ima artery is present, it contributes significantly to arterial supply.

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

4. Regarding the vascular supply to the thyroid gland:
A. It comes primarily from the superior and inferior thyroid arteries. T
B. The origin of the inferior thyroid artery is more constant than the superior. F
C. Small branches from the laryngeal and tracheo-oesophageal arteries also supply thyroid tissue. T
D. When the thyroidea ima artery is present, it contributes significantly to arterial supply. F

tanmay_mehta · Credits: 16591 My Scrapbook My Reading List 3 Books

explanation

The superior thyroid artery is the first branch of the external carotid;
the variable inferior thyroid usually arises from the thyrocervical trunk.
The thryoidea ima is present in 10%,
but is not a significant source of supply.

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