🔬general biology i review

Isthmus

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

An isthmus is a narrow strip of tissue connecting two larger parts of an organ or structure. In the endocrine system, it specifically refers to the part of the thyroid gland connecting its two lobes.

5 Must Know Facts For Your Next Test

  1. The isthmus of the thyroid gland connects the right and left lobes.
  2. Located anterior to the trachea, it typically spans across the second and third tracheal rings.
  3. It plays a role in maintaining thyroid hormone distribution between lobes.
  4. Variations in the size or presence of the isthmus can occur among individuals.
  5. Its involvement in endocrine function is crucial for metabolic regulation.

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