Topics

Topic

design image
Frontonasal suture

The frontonasal suture is a fibrous cranial suture located at the junction between the frontal bone and the nasal bones. It represents an important anatomical landmark of the anterior skull base and upper facial skeleton and plays a key role in craniofacial development and imaging interpretation.

The frontonasal suture must be carefully distinguished from fractures or developmental variants on radiologic studies, particularly in trauma and pediatric imaging.

Synonyms

  • Frontal–nasal suture

  • Fronto-nasal junction

Location

  • Located at the midline junction of the frontal bone and nasal bones

  • Extends transversely across the root of the nose

  • Inferior to the frontal suture (metopic suture)

  • Superior to the internasal suture

  • Forms part of the nasofrontal region

  • Deep to the soft tissues of the nasal root

Anatomical components

  • Fibrous cranial suture

  • Frontal bone (inferior margin)

  • Paired nasal bones (superior margins)

  • Adjacent landmarks:

    • Nasion (key surface landmark)

    • Glabella (superior to the suture)

  • Overlying soft tissues:

    • Skin

    • Subcutaneous tissue

    • Nasal musculature

    • Periosteum

Relations

Anteriorly:

  • Skin and soft tissues of the nasal root

Posteriorly:

  • Anterior cranial fossa floor (indirect)

  • Frontal lobes (superior and posterior relationship)

Superiorly:

  • Frontal bone

  • Metopic (frontal) suture

Inferiorly:

  • Nasal bones

  • Upper nasal cavity

Laterally:

  • Frontal process of the maxilla

  • Nasal bone margins

Developmental anatomy

  • Present at birth as a patent fibrous joint

  • Remains visible into adulthood as a normal craniofacial suture

  • Does not normally fuse completely, unlike the frontal (metopic) suture

  • Important growth site for the upper face and nasal bridge

X-ray appearance

Skull and facial bone radiographs:

  • Frontonasal suture: Thin, transverse or slightly curved radiolucent line at the nasal root

  • Margins: Smooth and corticated

  • Symmetry: Usually symmetric across the midline

  • Differentiation: Regular margins help distinguish it from fractures

CT appearance

Non-contrast CT:

  • Suture: Narrow hypodense linear interface between frontal and nasal bones

  • Margins: Well-defined cortical edges

  • Surrounding bones: Normal density and alignment

Post-contrast CT:

  • Suture: No enhancement

  • Adjacent soft tissues: Expected enhancement only

3D CT VRT appearance

Volume-rendered technique (VRT):

  • Frontonasal suture: Clearly visible seam at the nasal root

  • Surface anatomy: Smooth transition between frontal bone and nasal bones

MRI appearance

T1-weighted images:

  • Suture: Low-signal linear gap between frontal and nasal bones

  • Adjacent marrow: Intermediate to high signal within frontal and nasal bones

  • Overlying soft tissues: Normal signal intensity

T2-weighted images:

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

  • Surrounding bone marrow: Intermediate signal

CT image

Frontonasal suture ct

X-Ray image

Frontonasal suture