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Parietal bone

The parietal bone is a paired flat bone forming a major portion of the cranial vault. Together, the right and left parietal bones constitute the superior and lateral walls of the skull, providing protection to the cerebral hemispheres. Each parietal bone contributes to multiple cranial sutures and serves as an important landmark in neuroanatomy, radiology, neurosurgery, and anthropology.

The parietal bone is frequently evaluated in trauma, developmental assessment, and imaging of the skull vault.

Synonyms

  • Parietal bone of the skull

  • Cranial parietal bone

Location

  • Located on the superolateral aspect of the skull

  • Paired bones forming the roof and upper sides of the cranial vault

  • Posterior to the frontal bone

  • Anterior to the occipital bone

  • Superior to the temporal bones

  • Lateral to the sagittal midline

Anatomical components

  • External (outer) surface:

    • Smooth and convex

    • Contains the parietal eminence

    • Temporal lines for muscle and fascia attachment

  • Internal (inner) surface:

    • Concave

    • Grooves for middle meningeal vessels

    • Impressions of cerebral gyri

  • Borders:

    • Sagittal border: articulates with opposite parietal bone

    • Frontal border: articulates with frontal bone

    • Occipital border: articulates with occipital bone

    • Squamous border: articulates with temporal bone

  • Angles:

    • Frontal (bregmatic)

    • Occipital (lambdoid)

    • Mastoid

    • Sphenoidal

Relations

Externally:

  • Scalp and subcutaneous tissues

  • Galea aponeurotica

Internally:

  • Parietal lobes of the cerebral hemispheres

  • Superior sagittal sinus (near sagittal border)

  • Middle meningeal artery grooves

Anteriorly:

  • Frontal bone (coronal suture)

Posteriorly:

  • Occipital bone (lambdoid suture)

Inferiorly:

  • Temporal bone (squamous suture)

Medially:

  • Opposite parietal bone (sagittal suture)

Developmental anatomy

  • Develops by intramembranous ossification

  • Ossification center appears around the 8th week of gestation

  • Parietal eminence marks the primary ossification center

  • Sutures remain patent through childhood to allow brain growth

  • Complete suture fusion occurs gradually in adulthood

X-ray appearance

Skull radiographs (AP / lateral views):

  • Parietal bones: Smooth, symmetric calvarial outlines

  • Diploë: Radiolucent trabecular pattern between dense cortical tables

  • Sutures: Visible as thin radiolucent lines

  • Vascular grooves: Faint branching lucencies on inner table

CT appearance

Non-contrast CT:

  • Outer and inner tables: Hyperdense cortical bone

  • Diploic space: Lower-density marrow layer

  • Parietal eminence: Smooth outward contour

  • Internal grooves: Well-defined impressions for meningeal vessels

Post-contrast CT:

  • Bone: No enhancement

  • Adjacent dura and venous sinuses: Expected enhancement patterns

3D CT VRT appearance

Volume-rendered technique (VRT):

  • Parietal bones: Symmetric convex contours

  • Sutures: Clearly visualized articulations with frontal, occipital, and temporal bones

  • Surface anatomy: Parietal eminence appreciable

  • Utility: Excellent for assessing skull shape, fractures, and suture anatomy

MRI appearance

T1-weighted images:

  • Cortical tables: Low signal intensity

  • Diploic marrow: Intermediate to high signal (age dependent)

  • Scalp fat: High signal

T2-weighted images:

  • Bone cortex: Low signal

  • Diploë: Intermediate signal

  • Adjacent brain parenchyma: Normal parietal lobe signal

CT VRT 3D image

Parietal bone 3d

X-Ray image

X ray Parietal bone anatomy image -img-00000-00000