The thyroid gland and its variations: a cadaveric study.

The size and shape of the thyroid gland is subject to much variation, as stated by Wood Jones. Literature is replete with a large number of variations of the gland. By utilizing various techniques like gross dissection, histology, developmental anatomy, and recently thyroid scans and scintigraphy, some common and certain rare anomalies of the thyroid with their possible developmental bases are described in the literature. An attempt has been made to study the thyroid glands in 90 male cadavers available in our department, with ages ranging from 60 to 75 years with mean height of 5'4". The parameters that were observed included the length and width of lobes, presence or absence of pyramidal lobe, levator glandulae thyroideae, and isthmus with its relation to the tracheal rings. The average length of the right lobe was 4.32 cm, and the left lobe was 4.22 cm. The thickness of the right lobe was 1.13 cm, and the left lobe was 1.18 cm. Pyramidal lobe was present in 34 (37.77%) cases, frequently arising from the left lobe, while the levator glandulae thyroideae was present in 27 (30%) instances, mostly attached superiorly to the body of the hyoid bone. The isthmus was absent in 15 (16.66%) cases; its relation with the tracheal rings greatly varied from the cricoid cartilage to the fourth tracheal ring. Knowledge of variations of the thyroid assumes significance as this has relevance in the resection of thyroid, tumours, and tracheostomy.