Final answer:
The left and right lobes of the thyroid gland are connected by the isthmus, which is option 'c'. The isthmus helps in the formation of the butterfly shape of the thyroid gland which produces important hormones for the body.
Step-by-step explanation:
The left and right lobes of the thyroid gland are connected by the isthmus. The thyroid gland, located in the neck, plays a crucial role in the body's metabolism and calcium balance through the production of hormones like thyroxine (T4) and triiodothyronine (T3), as well as calcitonin. The parathyroid glands, which are important for regulating the body's calcium levels, are situated on the posterior surface of the thyroid gland.
Other terms such as the pyramidal lobe, major calyx, and loop of Henle are related to different anatomical structures. The loop of Henle, for instance, is part of the nephron found in the kidney and plays a role in urine concentration. The correct answer to the question is option 'c', the isthmus.