Anatomy of thyroid inter thyrio gland-1.pptx

thyroid

1. THYROID GLAND ANATOMY & HISTOLOGY Presented by Dr. milan dayani prime clinic

2. Structures in midline of the neck Mandible Hyoid Bone Thyroid Cartilage Cricoid Cartilage Thyroid Gland Trachea

3. It is a brownish red gland highly vascular Consists of 2 lobes and an isthmus between the lobes It extends from C5 to T1 Gross Morphology of The Thyroid Gland

4. The lobes are conical in shape. the apex of each being directed upwards the base looks downward, and is on a level with sixth tracheal ring. Each lobe is about 5 cm. long 2 cm width and 2cm thickness. Lobes are connected across the middle line by a narrow portion, the isthmus .

5. The isthmus extends across the midline in front of the second, third, and fourth tracheal rings A pyramidal lobe is often present, and it projects upward from the isthmus A fibrous muscular band frequently connects the pyramidal lobe to the hyoid bone ( the levator glandulae thyroidea )

6. The lateral (superficial surface) is convex, and covered by: the skin, the superficial and deep fascia the Sternocleidomastoid M. the superior belly of the Omohyoid , the Sternohyoid muscles Sternothyroid M. and pretracheal layer of the deep fascia, which forms a capsule for the gland. Surfaces and relations of the lobes **The firm attachment of the gland to the laryngoskeleton is responsible for movement of the thyroid gland and related structures during swallowing.

7. The deep or medial surface is moulded over the underlying structures: Lower part Trachea & Oesophagus Upper Part Thyroid cartilage & pharyngeal muscles

8. Posterolaterally : The carotid sheath with the common carotid artery, the internal jugular vein, and the vagus nerve

9. Arterial Blood Supply: The superior thyroid artery -branch of the external carotid artery Descends to the upper pole of each lobe Accompanied by the external laryngeal nerve The 2 arteries anastomose along upper border of isthmus

10. The inferior thyroid artery branch of the thyrocervical trunk ascends to the level of the cricoid cartilage, then turns medially and downward to reach the posterior border of the gland. The recurrent laryngeal nerve crosses either in front of or behind the artery, or it may pass between its branches. Arterial Blood Supply:

11. The thyroidea ima , if present arises from: the brachiocephalic artery Or the arch of the aorta. It ascends in front of the trachea to the isthmus

12. Anastomosis between the arteries

13. Best site for ligation of arteries In thyroid surgeries ?? ?? ?? Trachea Esophagus

14. Thyroid veins Superior Middle Inferior Venous drainage of the thyroid To internal jugular veins To brachiocephalic veins

15. Superior thyroid vein IJV Middle thyroid vein IJV Inferior thyroid vein Right or left brachiocephalic

16. Thyrocervical trunk Arises from the first part of subclavian A. Gives 3 branches: 1-Inferior thyroid A. 2-Transverse cervical A. 3-Suprascapular A. CCA

17. Lymphatic drainage passes frequently to: 1- lateral deep cervical lymph nodes. 2- pre- and parathracheal lymph nodes Lymphatic drainage of thyroid

18. Thyroid Variations Pyramidal lobe No isthmus + pyramidal lobe

19. They are 4 in number 2 Superior glands usually imbedded in fat on posterior surface of middle or upper portion of thyroid lobe 2 Lower glands near the lower pole of thyroid gland In 1-5% inferior gland in deep mediastinum Parathyroid gland Arterial supply usually from inferior thyroid artery Secrete Parathyroid hormone that help keeping the levels of calcium constant in blood

20. Branchial arches and Pharyngeal pouches form in the 4 th week Superior Parathyroids - the 4 th Pharyngeal pouch w/ thyroid Inferior Parathyroids – 3 rd Pharyngeal pouch w/ thymus