Surgery parathyroid gland applied anatomy.pptx

Surgery parathyroid gland

1. Applied Anatomy of parathyroid Gland Chetna Mudgal 35

2. The parathyroid glands, of which there are four, develop from the third and fourth pharyngeal pouches between the fifth and twelfth week of gestation. Superior parathyroids : from 4th pharyngeal pouch Inferior parathyroids: from 3rd pharyngeal pouch with thymus

3. They are typically described as ‘ Portland brick’ (yellow/brown) in colour and weigh approximately 30 mg Usually four glands – two superior, two inferior Superior parathyroids: constant in position, at the middle of posterior border of thyroid lobe. Inferior parathyroids: variable; usually near the lower pole of thyroid

4. Relations Anteriorly: Posterior surface of thyroid gland. Posteriorly: Prevertebral fascia and longus colli muscle. Laterally: Carotid sheath. Medially: Recurrent laryngeal nerve and tracheoesophageal groove.

5. Blood Supply Chiefly from the inferior thyroid artery. May also receive branches from the superior thyroid artery and thyroidea ima artery (if present).

6. Venous drainage: Into the thyroid venous plexus, → internal jugular and brachiocephalic veins .

7. Nerve Supply Sympathetic fibres from middle and inferior cervical ganglia. Act as vasomotor fibres. The secretory function of the parathyroids is mainly regulated by the concentration of calcium in the blood, with low calcium stimulating hormone release and high calcium inhibiting it

8. Surgical Relations Closely related to the recurrent laryngeal nerve, especially near the ligament of Berry. During thyroidectomy: Inferior thyroid artery should be ligated away from gland to preserve parathyroid blood supply. Injury or removal → hypoparathyroidism.

9. Variation in Position Inferior glands are more variable and may lie: Within the thyroid capsule, In the thymus, or In the mediastinum. Awareness of these variations helps in locating ectopic parathyroid tissue during surgery.

10. Parathyroid Disorders Hyperparathyroidism: Due to adenoma, hyperplasia, or carcinoma → hypercalcemia, renal calculi, bone resorption (“osteitis fibrosa cystica”). Hypoparathyroidism: May follow thyroid surgery → hypocalcemia, carpopedal spasm (Trousseau’s sign), laryngeal spasm, convulsions. Pseudohypoparathyroidism: Target organ resistance to PTH.

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