CorpusHuman Anatomy
SkeletalBone

Parietal bone

Os parietale

A paired, quadrilateral, curved plate forming most of the roof and upper sides of the cranial vault.

Show on body map Skull — Lateral View

Overview

Each parietal bone has four borders (sagittal, frontal, occipital and squamous) and four angles (frontal, sphenoidal, occipital and mastoid). The two parietal bones meet in the midline at the sagittal suture; they meet the frontal bone at the coronal suture, the occipital at the lambdoid suture and the temporal squama at the squamous suture. The sphenoidal (anteroinferior) angle reaches the greater wing of the sphenoid at the pterion.

The convex external surface has a parietal tuber (eminence) — the site of the primary ossification centre and the widest part of the skull — and the curved superior and inferior temporal lines (temporal fascia and temporalis). A small parietal foramen near the sagittal border transmits an emissary vein. The concave internal surface carries a midline groove for the superior sagittal sinus, granular foveolae for arachnoid granulations, and branching grooves for the middle meningeal vessels, deepest at the sphenoidal angle where the vessel may run in a bony tunnel. The mastoid angle bears a groove for the sigmoid sinus.

Location

Superolateral cranial vault, between frontal, occipital and temporal bones.

Parts & subdivisions

  1. Parietal tuber (eminence)
    Most convex point of the bone; primary ossification centre.
  2. Superior and inferior temporal lines
    Attachment of temporal fascia and temporalis muscle.
  3. Parietal foramen
    Transmits an emissary vein linking the superior sagittal sinus with scalp veins.
  4. Groove for superior sagittal sinus
    Shared midline groove with the opposite parietal bone.
  5. Grooves for middle meningeal vessels
    Arborising grooves on the inner surface, especially from the sphenoidal angle.

Anatomy

Articulations

Opposite parietal (sagittal suture), frontal (coronal), occipital (lambdoid), temporal (squamous) and sphenoid (sphenoparietal suture at the pterion).

Ossification

Intramembranous, from two centres near the parietal tuber appearing ≈week 8.

Function

  • Protects the parietal lobes and upper temporal lobes
  • Forms the roof and sides of the cranial cavity
  • Origin of temporalis (inferior temporal line area)

Clinical significance

Extradural haematoma

Fracture of the thin squamous temporal or sphenoidal angle region tears the anterior branch of the middle meningeal artery, producing a biconvex extradural haematoma that does not cross suture lines.

Cephalohaematoma

Subperiosteal bleed in the newborn after traumatic delivery, most often over a parietal bone; limited by suture lines (unlike caput succedaneum).

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.