The parietal bone forms most of the cranial roof and sides of the skull. It has four angles: frontal, sphenoidal, occipital, and mastoid. The four margins are frontal, occipital, squamous, and sagittal. The external surface has landmarks like the parietal tuber, superior and inferior temporal lines, and occasional parietal foramina. The internal surface has grooves for the superior sagittal and sigmoid sinuses and impressions from cerebral gyri.

1. Parietal
Bone
Skeletal System
Neurocranium
Dr. Aves Khan
Oral & Dental
Surgeon

2. Introduction of
Parietal Bone
The parietal bone (latin: os parietale) is located on each side of the skull
right behind the frontal bone.
Both parietal bones together form most of the cranial roof and sides of
the skull.
Each parietal bone takes an irregular quadrilateral shape and has four
angles, four margins, and two surfaces.

3. Angles of
Parietal Bone
The four angles of the parietal bone are:
 Frontal angle: its anterior superior angle
 Sphenoidal angle: It is the anterior inferior angle, and the most
sharpest angle of the parietal bone.
 Occipital angle: its posterior superior angle.
 Mastoid angle: It is the posterior inferior angle of the parietal
bone.

4. Margins of
Parietal Bone
The four margins or borders of the parietal bone are the following:
 Frontal margin: It forms its anterior border.
 Occipital margin: It forms the posterior border of the parietal
bone.
 Squamous margin: It is the inferior margin of the parietal bone.
 Sagittal margin: It is its upper, medial margin.

5. Surfaces and
landmarks of
parietal bone
The parietal bone has an external and an internal surface.
The external surface of the parietal bone features the following
landmarks:
 parietal tuber,
 superior temporal line,
 inferior temporal line,
 parietal foramen.
The internal surface of the parietal bone features:
 Groove for superior sagittal sinus
 Granular foveolae
 Groove for sigmoid sinus
 Impressions of cerebral gyri
 Arterial grooves

6. The external
surface of the
parietal bone
The parietal tuber (or parietal eminence) is a prominence located
near the middle of the external surface of the parietal bone.
The superior temporal line is a curved line seen on the external
surface of the parietal bone for attachment of the temporal
fascia. The superior temporal line also represents the upper
margin of the temporal plane.
The inferior temporal line is a curved line on the external surface
of the parietal bone for attachment of the temporalis muscle.
The parietal foramen is an opening occasionally present at the
back part of the parietal bone, that serves as a passage for the
parietal emissary vein, which drains into the superior sagittal
sinus.

7. Anatomical
views of the
Parietal bone

8. Dr. Aves Khan
Oral & Dental
Surgeon