Thyroid Gland |
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Position: | ||||||||||||||||||||
Antero- inferior part of the neck Isthmus is midline between second and fourth tracheal rings The lobes are antero-lateral between C4 and C6 Lobes are between trachea and esophagus medially and carotid sheath laterally. Deep to platysma and strap muscles. |
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Relations: | ||||||||||||||||||||
Isthmus
Lobes
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Blood supply: | ||||||||||||||||||||
Arterial Inferior thyroid artery from the thyrocervical trunk Superior thyroid artery from the external carotid artery. Occasional (unpaired) thyroidea ima (middle thyroid) from brachiocephalic trunk . Several unnamed twigs from pharyngeal and tracheal vessels. All these arteries anastomose with each other.
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Venous | |||||||||||||||||||||
Superior thyroid vein (A) – Internal jugular vein Middle thyroid vein (B) – Internal jugular vein Inferior thyroid vein (C) – Brachio cephalic vein. The inferior thyroid veins cover the trachea inferior to the thymus. They constitute potential sources of haemorrhage in tracheostomy. |
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Lymphatic drainage: |
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Inferior deep cervical lymph nodes [1]. Prelaryngeal lymph nodes [2] Paratracheal lymph nodes [3]. Pretracheal lymph nodes. [4] Some may empty directly into the thoracic duct. |
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Innervation: |
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Autonomic innervation from the cervical sympathetic ganglia and vagus. This innervation is vasomotor and affects the gland indirectly through the action on blood vessels. |
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