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Topic

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Frontal suture

The frontal suture, also known as the metopic suture, is a fibrous joint located in the midline of the frontal bone. It separates the two halves of the frontal bone during early development and normally fuses in early childhood. Persistence or premature fusion of this suture has important implications in cranial development and imaging interpretation.

The frontal suture is a key landmark in pediatric skull anatomy and radiology and must be distinguished from fractures or pathological lucencies on imaging.

Synonyms

  • Metopic suture

  • Median frontal suture

Location

  • Located in the midline of the frontal bone

  • Extends from the nasion inferiorly to the bregma superiorly

  • Situated between the paired frontal bones

  • Anterior to the coronal sutures

  • Superior to the nasal bones

  • Deep to the frontal scalp and superficial to the frontal lobes

Anatomical components

  • Fibrous cranial suture

  • Paired frontal bones (in infancy and early childhood)

  • Adjacent landmarks:

    • Nasion (inferior limit)

    • Bregma (superior limit)

  • Overlying scalp layers:

    • Skin

    • Dense connective tissue

    • Galea aponeurotica

    • Loose areolar tissue

    • Pericranium

Relations

Anteriorly:

  • Frontal scalp and subcutaneous tissues

Posteriorly:

  • Frontal lobes of the brain

  • Falx cerebri (posterior and inferior extension)

Superiorly:

  • Bregma

  • Sagittal suture

Inferiorly:

  • Nasion

  • Nasal bones

Laterally:

  • Frontal bones

  • Coronal sutures

Developmental anatomy

  • Present at birth as a patent fibrous suture

  • Physiologic fusion: Typically occurs between 6 months and 8 years of age

  • Complete fusion: Results in a single frontal bone

  • Persistent frontal suture: May remain visible into adulthood as a normal variant

X-ray appearance

Skull radiographs (AP / lateral views):

  • Frontal suture: Linear midline radiolucency in the frontal bone

  • Margins: Serrated or interdigitated edges

  • Extent: From nasion toward bregma (length varies with age)

  • Differentiation: Symmetric, well-defined lucency unlike fractures

CT appearance

Non-contrast CT:

  • Frontal suture: Thin hypodense linear cleft in the midline frontal bone

  • Margins: Well-corticated edges

  • Age-related change: May be absent after fusion or partially visible

Post-contrast CT:

  • Suture: No enhancement

  • Adjacent soft tissues: No abnormal enhancement

3D CT VRT appearance

Volume-rendered technique (VRT):

  • Frontal suture: Visible as a fine midline groove or seam

  • Extent: Variable length depending on fusion status

  • Surface morphology: Smooth, symmetric frontal contours

  • Utility: Excellent for assessing suture patency and cranial shape

MRI appearance

T1-weighted images:

  • Suture: Low-signal linear gap between frontal bone plates

  • Diploic marrow: Intermediate to high signal on either side

  • Overlying scalp fat: High signal

T2-weighted images:

  • Suture: Low-signal or CSF-equivalent thin line

  • Adjacent bone marrow: Intermediate signal

CT VRT 3D image

Frontal suture

X-Ray image

X rayFrontal suture anatomy image -img-00000-00000