thyroidsurgicalanatomy-161121065627.pptx

Goiter

1. SURGICAL ANATOMY & PHYSIOLOGY THYROID GLAND

2. EMBRYOLOGY AT 3 rd WEEK OF INTRA UTERINE LIFE DEVELOPS AS A ENDODERMAL THICKENING JUST BEHIND THE TUBERCULUM IMPAR @ FORAMEN CAECUM THIS THICKENING FORMS A DIVERTICULUM CALLED THYROGLOSSAL DUCT . THIS DESCENDS SLIGHTLY TO THE LEFT OF MIDLINE AND INFRONT OF THYROID CARTILAGE, IT BIFURCATES INTO TWO LOBES OF THYROID & CENTRAL PORTION FORMS THE ISTHMUS. THE PORTION OF THYROGLOSSAL DUCT NEAR THE ISTHMUS FORMS THE PYRAMIDAL LOBE .

3. IT IS THE FIRST GLAND TO BECOME FUNCTIONAL , ie ., BY 7 th WEEK OF INTRAUTERINE LIFE. SOMETIMES, THE PYRAMIDAL LOBE MAY BE ATTACHED TO BODY OF THE HYOID BONE BY A FIBROUS OR FIBROMUSCULAR BAND CALLED LEVATOR GLANDULAE THYROIDEAE. THE NEURAL CREST CELLS & CELLS FROM ULTIMOBRANCHIAL BODIES BECOME INCORPORATED INTO THE THYROID AND THEY FORM C –CELLS OR PARAFOLLICULAR CELLS.

4. EMBRYOLOGY

5. ANATOMY

6. ANATOMY THE LARGEST ENDOCRINE GLAND. EXTENDS FROM C5 TO T1 SPECIAL FEATURES ONLY ENDOCRINE GLAND LOCATED SUPERFICIALLY . ONLY ENDOCRINE GLAND WHICH DEPEND ON THE EXTERNAL ENVIRONMENT FOR RAW MATERIAL, IODINE, TO SYNTHESISE HORMONES. ONLY ENDOCRINE GLAND WHICH HAS THE ABILITY TO STORE THE HORMONES & RELEASE IT WHEN REQUIRED

7. WEIGHT OF THE GLAND – 25 gms . DIMENSION 5x3x2 cm LATERAL LOBE EXTENDS FROM OBLIQUE LINE OF THYROID CARTILAGE TO 5 th OR 6 th TRACHEAL RING THE ISTHMUS LIES INFRONT OF 2 nd & 3 rd TRACHEAL RINGS. IT HAS TWO CAPSULES. INNER TRUE CAPSULE FORMED BY PERIPHERAL CONDENSATION OF FIBROUS STROMA OF THE GLAND. OUTER FALSE CAPSULE FORMED BY THE PRETRACHEAL FASCIA . THE FIBROUS SEPTA ARISING FROM THE TRUE CAPSULE DIVIDE THE GLAND INTO MANY LOBULES .

8. MOVEMENT OF THE GLAND WITH DEGLUTITION REASONS: BERRY’S LIGAMENT IT CONNECTS THE LOBE OF THYROID TO THE CRICOID CARTILAGE. ISTHMUS IS ATTACHED TO THE TRACHEA. INVESTING PRETRACHEAL FASCIA SURROUNDING THE GLAND IS ATTACHED TO THE LARYNX & HYOID BONE.

9. RELATIONS F THYROID APEX EXTENDS ABOVE UPTO OBLIQUE LINE OF THYROID CARTILAGE SANDWICHED BETWEEN INF. CONSTRICTOR MEDIALLY AND STERNOTHYROID LATERALLY. BASE EXTENDS UPTO THE 5 th OR 6 th TRACHEAL RING. LATERAL SURFACE CONVEX SHAPED COVERED BY THREE STRAP MUSCLES ( sternothyroid , sternohyoid , superior belly of omohyoid ) ANTERIOR BORDER OF SCM

10. MEDIAL SURFACE 2 TUBES: Trachea & Esophagus 2 MUSCLES: Inferior cnstrictor & Cricothyroid 2 CARTILAGES: Cricoid & Thyroid POSTEROLATERAL SURFACE CAROTID SHEATH ANSA CERVICALIS CERVICAL SYMPATHETIC CHAIN ANTERIOR BORDER ANTERIOR BRANCH OF SUPERIOR THYROID ARTERY POSTERIOR BORDER PARATHYROID GLAND THIS BORDER CAN A PYRAMIDAL SHAPED EXTENSION CALLED TUBERCLE OF ZUCKERKANDL

11. ARTERIAL SUPPLY SUPERIOR THYROID ARTERY A BRANCH OF EXTERNAL CAROTIC ARTERY. SUPPLIES THE UPPER 1/3 rd OF LOBE & UPPER HALF OF ISTHMUS. INFERIOR THYROID ARTERY A BRANCH OF THYROCERVICAL TRUNK OF FIRST PART OF SUBCLAVIAN ARTERY. SUPPLIES LOWER 2/3 rd OF LOBE & LOWER HALF OF ISTHMUS. THYROIDEA IMA ARTERY A BRANCH FROM BRACHIOCEPHALIC TRUNK OR ARCH OF AORTA. ACCESSORY THYROID ARTERIES FROM TRACHEAL & ESOPHAGEAL ARTERIES.

12. ARTERIAL SUPPLY

13. THE SUPERIOR THYROID ARTERY IS CLOSELY RALATED TO THE EXTERNAL LARYNGEAL NERVE . THEY DIVERGE ONLY NEAR THE APEX OF THE GLAND, THE ARTERY LIES SUPERFICIAL & THE NERVE LIES DEEP TO THE APEX. HENCE, SUPERIOR THYROID ARTERY IS LIGATED AS CLOSE TO THE GLAND TO AVOID INJURY TO THE NERVE. THE RECURRENT LARYNGEAL NERVE LIES CLOSE TO THE INFERIOR THYROID ARTERY NEAR THE BASE OF THE GLAND. HENCE, THE ITA IS LIGATED AS AWAY FROM THE GLAND AS POSSIBLE TO AVOID INJURY TO THE RLN.

14. VARIOUS RELATIONSHIPS OF RLN WITH THE INFERIOR THYROID ARTERY

15. VENOUS DRAINAGE SUPERIOR THYROID VEIN DRAINS INTO THE INTERNAL JUGULAR VEIN MIDDLE THYROID VEIN SHORT, STOUT DRAINS INTO THE INTERNAL JUGULAR VEIN INFERIOR THYROID VEIN FORM PLEXUS INFRONT OF TRACHEA & DRAINS INTO THE LEFT BRACHIOCEPHALIC VEIN KOCHER’S VEIN EMERGE BETWEEN MIDDLE & INFERIOR THYROID VEIN TO DRAIN INTO THE INTERNAL JUGULAR VEIN

16. VENOUS DRAINAGE

17. RELATION B/W CAPSULE & VESSELS THE DENSE VENOUS PLEXUS LIES DEEP TO THE TRUE CAPSULE. THEREFORE,DURING THYROIDECTOMY, THE GLAND IS REMOVED ALONG WITH THE TRUE CAPSULE TO AVOID HEMORRHAGE.

18. LYMPHATIC DRAINAGE PRIMARY NODES PRE LARYNGEAL (DELPHIAN) NODE - LEVEL VI SINGLE NODE LOCATED ANTERIOR TO THE CRICOTHYROID MEMBRANE B/W CRICOTHYRID MUSCLES. PRE TRACHEAL & PARA TRACHEAL NODES PERITHYROID NODES MEDIASTINAL NODES SECONDARY NODES DEEP CERVICAL NODES SUPRA CLAVICULAR & OCCIPITAL NODES

19. LYMPHATIC DRAINAGE

20. NERVE SUPPLY PARASYMPATHETIC NERVE SUPPLY VAGUS & RECURRENT LARYNGEAL NERVE SYMPATHETIC NERVE SUPPLY SUPERIOR , MIDDLE & INFERIOR CERVICAL SYMPATHETIC GANGLION, MAINLY FROM MIDDLE.

21. MICRSCOPIC STRUCTURE

22. MICROSCOPIC STRUCTURE FOLLICULAR CELLS CUBOIDAL EPITHELIAL CELLS FORMING THE WALL OF SPHERICAL THYROID FOLLICLES. SECRETE THYROXINE – T4 TRIIODOTHYRONINE – T3 PARAFOLLICULAR OR C – CELLS PRESENT B/W THE FOLLICULAR CELLS SECRETE CALCITONIN

23. PHYSIOLOGY

24. SECRETION OF THYROID HORMONES THYROXINE – 93% TRIIODOTHYRONINE – 7% FUNCTIONAL ANATOMY OF THYROID EACH FOLLICLE CONSISTS WHICH IS COMPOSED OF THYROGLOBULIN THE THYROGLOBULIN IS SECRETED INTO THE FOLLICLE BY THE CUBOIDAL EPITHELIAL CELLS THE BLOOD SUPPLY IS FIVE TIMES THE WEIGHT OF GLAND EACH MINUTE. SECRETION OF PARAFOLLICULAR CELLS C CELL SECRETE CALCITONIN

25. REQUIREMENT OF IODINE 50 mg/year OR 1 mg/Week TABLE SALT IS IODISED WITH 1 PART OF NaI IN 1,00,000 PARTS 0F NaCl . FATE OF IODINE MOST OF THE ABSORBED IODINE IS EXCRETED SPONTANEOUSLY BY KIDNEYS. ONLY 1/5 th OF CIRCULATING IODINE IS TAKEN UP BY THE GLAND.

26. STEPS OF THYROID HORMONE FORMATION IODIDE TRAPPING BY THE SODIUM-IODIDE SYMPORTER INTO THYROID CELL BY PENDRIN , FROM THYROID CELL INTO FOLLICULAR CELL. OXIDATION OF IODIDE ION INTO IODINE CATALYSED BY THE ENZYME PEROXIDASE ORGANIFICATION OF THYRGLOBULIN BINDING OF IODINE WITH THYROGLOBULIN WITH THE HELP OF THYROID PEROXIDASE .

27. COUPLING OF IODOTYROSINE RESIDUES DIT + DIT -------  T4(THYROXINE) MIT + DIT ------T3(TRIIODOTHYRONINE) DIT + MIT ------ RT3(REVERSE T3) RELEASE OF T3 & T4 INTO THE BLOOD T3 & T4 ARE CLEAVED FROM THE THYROGLOBULIN TO GET RELEASED INTO THE CIRCULATING BLOOD. FIRSTLY THE THYROGLOBULIN IS ENDOCYTOSED INTO THE FOLLICULAR CELLS. THEN, THE PROTEOLYSIS TAKES PLACE TO RELEASE T3 & T4 INTO THE BLOOD. STORAGE OF THYROGLOBULIN EACH THYROGLOBULIN MOLECULE CAN CONTAIN UPTO 30 THYROXINE & FEW T3 MOLECULES.

28. CR

29. IODINE RECYCLING ALMOST 3/4 th OF THE IODINATED THYROID HORMONES ARE MIT & DIT. SO, DURING DIGESTION OF THYROGLOBULIN, IODINE IS CLEAVED FROM THEM BY DEIODINASE ENZYME. TRANSPORT OF T3 & T4 COMBINED WITH TBG – THYRID BINDING GLOBULIN TBPA – THYROID BINDING PRE ALBUMIN ALBUMIN AFTER ENTERING THE CELL T3 & T4 GET INCORPORATED INTO THE INTRACELLULAR PROTEINS. OF THESE TWO, T4 HAS MORE AFFINITY FOR TG & BIND STRONGLY WITH INTRACELLULAR PROTEINS. HENCE IT HAS LONG DURATION OF ACTION.

30. FUNCTIONS OF THYROID HORMONES REGULATION OF BASAL METABOLIC RATE REQUIRED FOR NORMAL PSYCHOSOMATIC GROWTH HAS CHRONOTROPIC & IONOTROPIC EFFECT ON HEART INCREASES THE SENSITIVITY OF RECEPTORS TO CATECHOLAMINES & ALSO INCREASES THE NO. OF RECEPTORS REQUIRED FOR NORMAL RESPIRATORY DRIVE REQUIRED FOR NORMAL HEMATOPOIESIS THYROXINE HAS OPPOSITE EFFECT OF INSULIN INCREASES THE BONE TURNOVER

31. FUNCTIONS OF CALCITONIN IT DECREASES THE SERUM CALCIUM LEVEL BY REDUCING THE BONE RESORPTION REGULATION OF THYROID HORMONE SYNTHESIS BY TSH ACTIVATION OF CYCLIC AMP BY TRH EXPOSURE TO COLD NEGATIVE FEEDBACK MECHANISM

32. THANK YOU !!!