Скачать или смотреть GALEN ANASTOMOSIS &HUMAN COMMUNICATING NERVE

The anastomosis of Galen (between the internal branch of the superior laryngeal nerve and the recurrent laryngeal nerve) is not always present.

📌 Incidence in normal population (cadaveric/anatomical studies):
• Present in about 70–80% of individuals (varies slightly between studies).
• A minority of people (~20–30%) lack this anastomosis.

🔎 Clinical significance:
• When present, it provides an alternative sensory pathway to the larynx.
• Its absence can make the laryngeal mucosa more vulnerable after recurrent laryngeal or superior laryngeal nerve injury.
Human Communicating Nerve (HCN)
• It is a nerve communication between the external branch of the superior laryngeal nerve (EBSLN) and the recurrent laryngeal nerve (RLN).
• Unlike Galen’s anastomosis (which is internal branch of SLN ↔ RLN, purely sensory), the HCN may carry motor fibers.

Incidence
• Reported in ~40–85% of the population (wide variability due to anatomical study methods).
• Studies suggest it may provide motor innervation from EBSLN to intrinsic laryngeal muscles (especially cricothyroid and sometimes contributing to thyroarytenoid), which has surgical importance.

Clinical Significance
1. During thyroid or neck surgery, injury to the EBSLN may not cause complete cricothyroid paralysis if HCN is present, because motor fibers may cross to RLN.
2. Voice preservation: Surgeons must be aware of it, as sparing the HCN can reduce postoperative voice changes.
3. Explains why RLN palsy sometimes does not cause complete vocal fold paralysis (because of motor crossover through HCN).

✅ Summary:
• Galen’s Anastomosis = Internal SLN ↔ RLN (purely sensory, 70–80% incidence).
• Human Communicating Nerve = External SLN ↔ RLN (motor component possible, 40–85% incidence).
References scott brown and sataloff