Forehead-to-Nasal Tip Ratio

Forehead-to-Nasal Tip Ratio

Fronto-Maxillary Facial (FMF) Angle

• Definition: Angle between the line along the upper surface of the maxilla and the line along the frontal bone.
• Normal Range: ~76–83° at 11–13⁺⁶ weeks
• Clinical Relevance: Helps assess facial disproportions or micrognathia
• Increased FMF Angle: Associated with Down syndrome (Trisomy 21)
• How to Measure:
  • Mid-sagittal view of the face
  • One line: along the upper aspect of the maxilla
  • Second line: tangential to the frontal bone
  • Measure the angle between these two lines

Forehead-to-Nasal Tip Ratio

• This is a relatively rarely used soft marker assessed during first-trimester NT (Nuchal Translucency) screening.
• It is a craniofacial ratio calculated on a mid-sagittal plane ultrasound image using two linear measurements:
• Forehead Length: From the leading edge of the frontal bone to the nasion (root of the nose).
• Nasal Tip Length: From the nasion to the nasal tip.
• Formula: Forehead-to-Nasal Tip Ratio = Forehead Length / Nasal Tip Length