Thyroid and Salivary Glands Flashcards
Thyroid Gland:
Location: (2)
- Lies deep to the sternothyroid and sternohyoid muscles
- Located anteriorly in the neck at the level of C5-T1 vertebrae
Thyroid gland
* Anteriorly- (2)
* Posteriorly-
* Posterolateral-
- Anteriorly-
o Loose sheath formed by pretracheal fascia
o Sternohyoid and sternothyroid - Posteriorly- cricoid cartilage and upper 2-3 tracheal rings
- Posterolateral- carotid sheaths and their contents
What is the structure of the thyroid gland? (3)
- Consists primarily of right and left lobes anterolateral to the larynx and trachea
- A thin isthmus unites the lobes over the trachea anterior to 2nd and 3rd tracheal rings
- Surrounds by a thin fibrous capsule which sends septa deeply into the gland
What is the function of the thyroid gland? (2)
- Endocrine gland- ductless gland that secretes directly into the blood
- Secretes
o Thyroid hormone
What is the function of thyroid hormone? (3)
- Acts on whole body except itself, the uterus and spleen
- Controls metabolic rate
o Calcitonin - Controls calcium metabolism
Arterial supply of the thyroid hormone:
* Superior and inferior thyroid arteries lie between the ____ ______ and loose fascial sheath
fibrous capsule
Arterial supply
* Superior thyroid artery from external carotid artery: (2)
o Descends to superior poles of the gland, pierces pretracheal layer
o Supplies anterosuperior aspect
Arterial supply
* Inferior thyroid artery from thyrocervical trunk of subclavian artery: (2)
o Run superomedially posterior to carotid sheaths
o Supplies posteroinferior aspect
What is the Thyroid ima artery? (2)
o In 10% of people
o Small unpaired artery ascending on the anterior surface of trachea to supply the gland
Venous Drainage
* Thyroid venous plexus on the anterior surface is formed by 3 veins:
o Superior thyroid veins
o Middle thyroid veins
o Inferior thyroid veins
What is the superior thyroid vein? (2)
- Accompany the superior thyroid veins
- Drain the superior poles
What are the middle thyroid veins? (2)
- Run parallel to the inferior thyroid arteries
- Drain the middle lobes
What are the inferior thyroid veins? (2)
- Run independently
- Drain the inferior poles
Venous drainage:
* Superior and middle thyroid veins drain into the ____ _____ veins
* Inferior thyroid vein drains into the ________ vein posterior to manubrium
internal jugular
brachiocephalic
Lymphatic Drainage:
How does this take place? (2)
- Lymphatic vessels run in the interlobular connective tissue
- Communicate with a capsular network of lymphatic vessels
Lymphatic Drainage:
* Superiorly:
o Prelaryngeal lymph nodes drain into superior deep cervical lymph nodes
Lymphatic Drainage:
* Inferiorly:
o Pretracheal and paratracheal lymph nodes drain into inferior deep cervical nodes
Lymphatic Drainage:
* Laterally:
o Vessels located along the superior thyroid veins pass directly into the inferior deep cervical lymph nodes
Lymphatic drainage:
* Some vessels drain into brachiocephalic nodes or _______ _____.
thoracic duct
Innervation
* Sympathetic
o Superior middle and inferior cervical ganglia via: (3)
- Cardiac periarterial plexus
- Superior thyroid periarterial plexus
- Inferior thyroid periarterial plexus
Innervation
* Parasympathetic:
o Superior and recurrent laryngeal nerves from vagus nerve
- All fibres are ______
o They constrict blood vessels
vasomotor
What are Recurrent laryngeal nerves? (4)
- Arise from vagus nerve in the inferior part of the neck
- Right recurrent loops inferior to right subclavian a. at T1-T2
- Left recurrent loops inferior to aortic arch at T4-T5
- Both ascend superiorly to the posteromedial aspect of the thyroid gland
Parathyroid glands:
* Location and structure: (2)
o Small flattened, oval glands
o Lie external to the thyroid capsule on the medial half of the posterior surface of each lobe of the thyroid gland within the pretracheal fascia
