menu_book Anatomy • 10 min read

Facial Nerve in Surgery: Anatomy, Danger Zones and Protection

Complete guide on facial nerve in surgery: anatomy of 5 branches, danger zones, protection techniques and why subperiosteal plane is safer.

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Dr. Roberio Brandao

Creator of Modern Face

Updated December 17, 2024

Why Is the Facial Nerve So Important? The facial nerve (VII cranial nerve) controls all facial expression. An injury can cause partial or total paralysis of one side of the face — one of the most feared complications in facial surgery and one of the main reasons why many surgeons avoid deep plane procedures. However, with adequate anatomical knowledge and appropriate technique, risk can be minimized to very low levels. The [Modern Face philosophy prioritizes Maximum Safety precisely by developing techniques that maintain safe distance from the nerve.

“There is no aesthetic result that justifies nerve injury. Safety is non-negotiable.”

  • — Dr. Robério Brandão

Facial Nerve Anatomy

The facial nerve emerges from the stylomastoid foramen, traverses the parotid gland where it divides, and distributes five main branches. A useful mnemonic: “Two Zebras Bit My Cookie” (Temporal, Zygomatic, Buccal, Marginal, Cervical).

📍 Fundamental Principle

The facial nerve runs in the sub-SMAS layer, deep to the fascia but superficial to the periosteum. It is ABOVE the subperiosteal plane — that’s why this plane is safer.

The 5 Branches: Function, Injury and Protection

Branch

Function: If injured: Danger zone: Protection: )) }

Why Is the Subperiosteal Plane Safer? The key to understanding subperiosteal plane safety lies in the layered anatomy:

Layers (Superficial → Deep)

1 Skin

2 Subcutaneous fat

3 SMAS / Temporoparietal fascia

4 FACIAL NERVE (in sub-SMAS layer)

5 Deep fascia / Parotid-masseteric

6 PERIOSTEUM (Endomidface dissection plane)

7 Bone

The Endomidface works in plane 6 (subperiosteal). The nerve is in plane 4. There are two layers of tissue between the dissection plane and the nerve — a significant safety margin.

✅ Advantages of Subperiosteal

  • • Facial nerve is ABOVE the dissection plane
  • • Avascular plane (less bleeding)
  • • Predictable and reproducible dissection
  • • Allows direct vision without increased risk
  • • Less affected by biostimulators

Frequently Asked Questions

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Complications Prevention

A comprehensive guide on surgical safety and risk management.

SMAS Anatomy

Understanding the layer where the facial nerve resides.

Endomidface Guide

Details on the subperiosteal technique for maximum safety.

For surgeons: Learn safe dissection techniques in our [advanced surgical mentorships.

Learn Applied Anatomy in Practice

Mentorship programs include detailed surgical anatomy with focus on safety.

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Frequently Asked Questions

What's the risk of facial nerve injury in facelift?

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In experienced hands with proper technique, the risk of permanent facial nerve injury is very low (<0.5-1%). Temporary weakness is more common (2-5%), resolving in weeks to months. The Modern Face technique with subperiosteal plane has a record of zero permanent injuries in over 1,500 cases.

Which facial nerve branches are most vulnerable?

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The marginal mandibular branch (for lower lip) and the frontal/temporal branch (for eyebrow) are most vulnerable due to their superficial course. The zygomatic branch has more anastomoses, providing some redundancy.

Why is the subperiosteal plane safer?

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The facial nerve runs in the sub-SMAS layer/deep to the fascia. The subperiosteal plane is BELOW the nerve — between the periosteum and bone. Working in this plane maintains safe distance from the nerve, which remains in more superficial layers.

How to know if there was facial nerve injury?

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Signs include: inability to raise eyebrow (frontal branch), weakness in eye closure (zygomatic branch), smile asymmetry (buccal branch), inability to lower lower lip (marginal branch). Immediate postoperative evaluation detects problems.

Is facial nerve injury reversible?

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Traction or neuropraxia injuries (stretching) generally recover in weeks to months. Transection injuries are more serious and may require microsurgical repair. The vast majority of post-facelift changes resolve spontaneously.

What to do if nerve injury is suspected?

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Document the deficit, reassure the patient (most resolve), start early physical therapy, consider electroneuromyography evaluation after 3 weeks. If transection confirmed, surgical exploration may be necessary.

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