Anatomical and surgical aspects of the lobes of the thyroid glands.

Variation in the descent of the thyroid gland and during fetal life and regression of the thyroglossal duct is associated with many variations in form of the mature gland. The shape and morphometric details of gland, its extension as the pyramidal lobe (PYR-L) and attachments of the levator glandulae thyroidea were studied in 40 cadavers. We categorized the shape of the thyroid into 12 types. The most frequent type was PYR-L with 22.5% which started from the left lobe and moved across by intercrossing the larynx. Horseshoe-shaped gland and the gland with separate lobes were the most frequently observed glandular shapes, with 17.5 and 20%, respectively. The incidences of the PYR-L and the levator glandulae thyroideae were 60 and 17.5%, respectively. The pyramidal lobe branched off more frequently from the left part of the isthmus (14 specimens) than from the right (5 specimens) or the midline (2 cases). Knowledge about the glandular landmarks and anatomic measurements around the thyroid will be helpful for the surgeon to constitute a simplification of the topographic anatomy, plan and decide on a safe approach to the thyroid gland, and to avoid postoperative complications.