The superficial head is the larger component of the masseter, providing the dominant jaw-closing force. Its fibres run inferomedially from the zygomatic arch to the mandibular angle, producing a powerful closing torque.
| Origin | Anterior two-thirds of the zygomatic arch — inferior border |
|---|---|
| Insertion | Lateral surface of the mandibular ramus and angle |
| Nerve Supply | Masseteric nerve — branch of mandibular nerve (V3) |
| Blood Supply | Masseteric artery |
| Actions | Closes the jaw — primary jaw closer with medial pterygoid; Protrudes the mandible slightly |
|---|
The superficial head is the target for botulinum toxin injection in masseter hypertrophy and bruxism — injection is placed in the lower lateral masseter bulk to avoid the parotid duct. Superficial masseteric hypertrophy produces visible jaw widening that is treated by progressive botulinum injections or surgical partial resection.
Visible as the lateral jaw bulk during clenching — the superficial head is the prominent inferior belly.
Unilateral or bilateral masseter hypertrophy from bruxism or parafunctional habits producing jaw widening, treated by botulinum toxin injection targeting the superficial head.
