Facial nerve: branches and why it matters in HOF
The facial nerve is the seventh cranial nerve. Its main function in the face is motor: it controls the muscles of facial expression, responsible for raising the eyebrows, closing the eyes, smiling and moving the lips. It also has fibers linked to taste and to the salivary and lacrimal glands.
After leaving the skull, it passes through the parotid gland and divides into five main branches:
- Temporal: frontalis muscle and part of the orbicularis oculi.
- Zygomatic: orbicularis oculi and cheek muscles.
- Buccal: muscles around the nose and upper lip.
- Marginal mandibular: muscles that lower the lower lip and the corner of the mouth.
- Cervical: platysma, in the neck.
Why does the facial nerve matter in HOF?
First, because botulinum toxin acts precisely at the junction between these nerves and the muscles. Understanding which branch controls which muscle helps predict the effect of treating dynamic wrinkles and explain unwanted effects, such as smile asymmetry or a dropping eyebrow when the product reaches a neighboring muscle.
Second, because the assessment should record facial function before any procedure. A previous paralysis (such as Bell's palsy), a surgical sequela or a facial asymmetry of neurological origin change the plan and must be noted in the patient record and in the initial photos.
Direct injury to the nerve by injectable procedures is uncommon, because the branches usually run in deeper planes, below the SMAS. Even so, knowing the course is part of safety, especially in thread techniques. Indication and technique are defined by the qualified professional, in line with the rules of their professional council in Brazil.
In Harmy
Harmy's projection works on the photo at rest and does not change the patient's expression. Assessing the face in motion remains part of the consultation.
Also called: seventh cranial nerve, cranial nerve VII, CN VII.