Triangles in Thyroid Surgery
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🔺 Important Triangles in Thyroid Surgery
🐻 Beahr’s Triangle
📐 Boundaries:
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Base: Common carotid artery
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Superior: Inferior thyroid artery
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Inferomedial: Recurrent laryngeal nerve
🎯 Clinical Importance:
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Found posterior to the thyroid gland after retracting it medially.
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Helps locate the recurrent laryngeal nerve (RLN) and avoid injury during surgery.
What is Beahr's triangle also known as?
🧊 Simon’s Triangle
📐 Boundaries:
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Superior: Inferior thyroid artery
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Lateral: Common carotid artery
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Medial: Esophagus or trachea
📦 Content:
- Recurrent laryngeal nerve passes through this triangle.
🎯 Clinical Importance:
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Unlike Beahr’s triangle, recurrent laryngeal nerve is a content here.
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Important zone for recurrent laryngeal nerve identification intraoperatively.
📐 Joll’s Triangle
📐 Boundaries:
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Superior: Superior attachment of strap muscles
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Medial: Midline of the neck
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Lateral: Superior pole of thyroid & superior thyroid vessels
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Floor: Cricothyroid muscle
📦 Content:
- External branch of the superior laryngeal nerve (EBSLN)
🎯 Clinical Importance:
- Identify and preserve EBSLN to avoid voice pitch issues post-thyroidectomy.
What is Joll's triangle also known as?
📏 Lore’s Triangle
📐 Boundaries:
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Medial: Trachea
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Lateral: Common carotid artery
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Superior: Inferior pole of thyroid gland
📦 Content:
- Recurrent laryngeal nerve
🎯 Clinical Importance:
- Key zone to locate and protect the recurrent laryngeal nerve during surgery.
🔻 Recurrent Laryngeal Nerve Triangle
📐 Boundaries (Inverted Triangle):
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Apex: Thoracic inlet
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Medial: Trachea
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Lateral: Medial edge of retracted strap muscles
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Superior: Lower edge of inferior thyroid pole
📦 Content:
- Recurrent laryngeal nerve as a single trunk
🎯 Clinical Importance:
- Identifying the recurrent laryngeal nerve trunk near thoracic inlet helps avoid nerve damage during lower pole dissection.
⚠️ Triangle of Concern
📐 Boundaries:
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Medial: Trachea
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Lateral: Recurrent laryngeal nerve
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Base: Thyrothymic ligament & loose fat over sternum
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Apex: Berry’s ligament
📦 Content:
- Small arterial branches of the inferior thyroid artery
🎯 Clinical Importance:
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Commonest site of bleeding during thyroidectomy.
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Lies close to recurrent laryngeal nerve → requires careful hemostasis to prevent nerve injury.
🧵 Cricothyroid Space of Reeves
- Avascular space between upper thyroid pole and cricothyroid muscle
📦 Content:
- External branch of superior laryngeal nerve (EBSLN) enters this space.
🎯 Clinical Importance:
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Open and inspect this space to preserve EBSLN.
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Retraction of the thyroid lobe here reveals Joll’s triangle.
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🧩 Summary Table
| Triangle | Key Nerve Involved | Main Use |
|---|---|---|
| Beahr’s Triangle | Recurrent Laryngeal Nerve (boundary) | Avoid nerve injury |
| Simon’s Triangle | Recurrent Laryngeal Nerve (content) | RLN identification intraop |
| Joll’s Triangle | External Branch of SLN | Preserve EBSLN |
| Lore’s Triangle | Recurrent Laryngeal Nerve | Nerve localization |
| RLN Triangle | Recurrent Laryngeal Nerve (trunk) | Identification near thoracic inlet |
| Triangle of Concern | RLN + Inferior Thyroid Artery branches | Bleeding control |
| Cricothyroid Space of Reeves | External Branch of SLN | Entry point for EBSLN |
📝 Final Notes
Out of the seven triangles,
✅ Two triangles relate to the external branch of superior laryngeal nerve:
- Joel’s Triangle
- Cricothyroid Space of Reeves
⚠️ Five triangles involve the recurrent laryngeal nerve, either as a content or boundary.
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