---
title: "Anatomy of Thyroid Gland"
description: "ENT notes on anatomy of thyroid gland - lobes, relations, blood supply, lymphatic drainage, nerve supply, and clinical importance."
source: "The ENT Resident"
author: "Dr. Mausumi Das"
canonical_url: "https://www.theentresident.com/ent-notes-lectures/anatomy-of-thyroid"
categories: ["Thyroid"]
video: "https://www.youtube.com/watch?v=-AZUdTA_8Kg"
image: "https://media.theentresident.com/og-images/anatomy-of-thyroid.png"
---

# Anatomy of Thyroid Gland

ENT notes on anatomy of thyroid gland - lobes, relations, blood supply, lymphatic drainage, nerve supply, and clinical importance. Watch the full video lecture on YouTube: https://www.youtube.com/watch?v=-AZUdTA_8Kg

## 🧠 Anatomy of the Thyroid Gland

The **thyroid gland** is a highly vascular, ductless endocrine gland with several unique anatomical and physiological features. 

In this post, we’ll cover its **location, parts, coverings, blood supply, lymphatic drainage, nerve supply**, and important **clinical correlations**.

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### 📍 Location of the Thyroid Gland

- Located **anterior to the upper trachea**, opposite **C5–T1 vertebrae**.

- **Lateral lobes** extend from the middle of the **thyroid cartilage** to the **4th or 5th tracheal ring**.

- **Isthmus** lies opposite the **2nd to 4th tracheal rings**.

---

### 🔹 Parts of the Thyroid Gland

- 2 lateral lobes
- Isthmus connecting the lobes
- Pyramidal lobe (in 50–60% of individuals)
- Zuckerkandl's tubercle (in ~60% individuals)

---

### 📏 Size and Weight

- Each lobe:  
  - **Length**: 5 cm  
  - **Width**: 3 cm  
  - **Depth (A-P)**: 1.5 cm  

- Average weight: **20–25 g** (larger in females)

- Increases during **menstruation and pregnancy**

---

### 🧥 Capsules of the Thyroid

- **True Capsule**: Peripheral condensation of the fibrous stroma.

- **False Capsule**: Derived from **pretracheal fascia**.

>What is the clinical significance of the thyroid capsules?

>Why does thyroid swellings move up and down with degluttition?
---

### 📌 Berry’s Ligament (Suspensory Ligament)

- Thickening of the pretracheal fascia.
- Attaches **posteromedial surface** of the lobe to the **cricoid cartilage** and **upper tracheal rings**.

>What is the clinical significance of Berry’s Ligament?

---

### 🧭 Surfaces, Borders & Relations

**🔼 Apex**

- Points **upward and laterally**

- Lies between:
  - **Inferior constrictor** (medial)
  - **Sternothyroid** (lateral)

- Related to:
  - **Superior thyroid artery** (superficial)
  - **External laryngeal nerve** (deep)  
  
>Where should you ligate Superior thyroid artery in Thyroidectomy?

**🔽 Base**

- Extends to **5th/6th tracheal ring**

- Related to:
  - **Inferior thyroid artery**
  - **Recurrent laryngeal nerve**  

>Where should you ligate Inferior thyroid artery in Thyroidectomy?

**🟪 Anterolateral Surface**

Overlapped by (from deep to superficial):
- Sternothyroid
- Sternohyoid
- Superior belly of omohyoid
- Sternocleidomastoid

**🔷 Medial Surface**

- **2 Tubes**: Larynx & Trachea, Pharynx & Esophagus  
- **2 Muscles**: Inferior constrictor, Cricothyroid  
- **2 Nerves**: External laryngeal, Recurrent laryngeal

**🟩 Posterolateral Surface**

- Related to **carotid sheath and contents**

**🔸 Anterior Border**

- Relation: **Anterior branch of superior thyroid artery**

**🔹 Posterior Border**

- **Anastomosis** of superior & inferior thyroid arteries
- **Parathyroid glands**
- **Thoracic duct** (on left)

---

### 🔗 Isthmus of Thyroid Gland

- **Dimensions**: 1.25 × 1.25 cm

- **Anterior Relations**: Sternothyroid, sternohyoid, fascia, anterior jugular vein, skin

- **Posterior Relation**: 2nd to 4th tracheal rings

- **Lower Border**: Inferior thyroid veins, thyroidea ima artery (if present)

- **Upper Border**:
  - Anastomosis of **superior thyroid arteries**
  - **Pyramidal lobe** (remnant of thyroglossal duct)
  - **Tubercle of Zuckerkandl**

>What is Pyramidal lobe? What is its clinical importance?

>What is Tubercle of Zuckerkandl? What is its clinical importance?

---

### 🩸 Arterial Supply of Thyroid Gland

| Artery | Origin | Notes |
| --- | --- | --- |
| Superior thyroid | External carotid artery | Divides into anterior & posterior branches |
| Inferior thyroid | Thyrocervical trunk (from subclavian) | Related to recurrent laryngeal nerve |
| Thyroidea ima | Brachiocephalic trunk (12%) | Supplies isthmus |
| Accessory arteries | Tracheal/esophageal branches | Medial supply |

---

### 💉 Venous Drainage of Thyroid Gland

| Vein | Drains Into | Notes |
| --- | --- | --- |
| Superior thyroid vein | Internal jugular vein | Upper pole |
| Middle thyroid vein | Internal jugular vein | Middle lobe |
| Inferior thyroid vein | Left brachiocephalic vein | Isthmus |
| Cocker’s vein | Internal jugular vein | From lower pole (variable) |

---

### 🧬 Lymphatic Drainage of Thyroid Gland

- **Lateral gland** → **Level III, IV** (jugular nodes), sometimes **Level V**

- **Medial gland** → **Level VI** (prelaryngeal, pretracheal, paratracheal)  
  → then to **Level VII** (anterior mediastinal nodes)

---

## ⚡ Nerve Supply of Thyroid Gland

| Type | Source |
| --- | --- |
| Parasympathetic | Vagus nerve |
| Sympathetic | Middle cervical ganglion (main), also superior & inferior cervical ganglia |

**Closely Related Nerves**:
- **Recurrent laryngeal nerve**
- **External branch of superior laryngeal nerve**

>How is the Recurrent laryngeal nerve related to the thyroid gland?

>What will injury to the Recurrent laryngeal nerve present as?

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## About This Note

This free ENT note on Anatomy of Thyroid Gland was written by Dr. Mausumi Das and is paired with a corresponding video lecture.

Canonical page of this note: https://www.theentresident.com/ent-notes-lectures/anatomy-of-thyroid

When citing or referencing this content, please credit The ENT Resident and link to the canonical page above.

## Related Notes by Category

- Thyroid: https://www.theentresident.com/ent-notes-lectures/category/thyroid.md

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The ENT Resident is an educational website and resource library created by Dr. Mausumi Das (MS ENT) for ENT residents, ENT postgraduates preparing for exams, and MBBS students.

Dr. Mausumi Das writes the notes, draws the diagrams, and records the lectures herself.

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