The frontal bone forms the forehead region and contributes to the cranium. It has four parts - the squamous, orbital, and nasal parts. The squamous part forms most of the forehead and houses the frontal sinuses. The orbital part forms the roof of the orbits. The nasal part forms part of the nasal cavity roof. The frontal bone has several external landmarks including the frontal eminences, glabella, supraorbital margins, and zygomatic processes. Internally it has a frontal crest and groove for the superior sagittal sinus.

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

2. Introduction of
Frontal Bone
The frontal bone (latin: os frontale) is an unpaired bowl-shaped bone
located in the forehead region, which contributes in forming the
cranium.
The frontal bone lies superior to the nasal bones and anterior to the
parietal bones.

3. Parts of
Frontal Bone
The Frontal bone has 4 parts –
1. squamous part,
2. orbital part (2),
3. nasal part.

4. Squamous part of
the frontal bone
 It is the largest part of the frontal bone which forms the area of
the forehead.
 The squamous part of the frontal bone houses the frontal
sinuses, which are separated by a septum and are located above
the orbits.

5. Orbital or
horizontal part of
the Frontal bone
 It forms the roof of the orbit and ethmoidal sinuses.
The orbital part consists of two orbital plates separated by a
gap - the ethmoidal notch.

6. Nasal part of
the Frontal bone
 It is located anteriorly between the two orbital parts of
the frontal bone forming part of the roof of the nasal cavity.

7. Surfaces and
landmarks of
frontal bone
The frontal bone has an external and an internal surface. Several
landmarks and structures can be found on each surface.
The external surface of the frontal bone features:
frontal eminence (2),
superciliary arch (2),
glabella,
supraorbital margin (2), featuring
 frontal notch (or foramen),
 supraorbital notch (or foramen),
zygomatic process (2),
temporal line,
temporal surface.

8. The external surface
of the frontal bone  The frontal eminence is a round elevation on the frontal
bone located above the supraorbital margin on each side of the
frontal suture.
 The superciliary arch is an elevation on the frontal bone above
the upper margin of the orbit. Both superciliary arches are joined
together by the glabella.
 The glabella is a smooth elevation on the frontal bone, a
landmark between the two superciliary arches.
 The supraorbital margin is the upper orbital margin of the frontal
bone.

9. The external surface
of the frontal bone
 The frontal notch (sometimes presenting as frontal foramen) is
an opening on each of the supraorbital margins of the frontal
bone medial to the supraorbital notch (or foramen).
 The frontal notch or foramen serves as a passage for the
supratrochlear artery and the medial branch of the supraorbital
nerve.
 The supraorbital notch (sometimes presenting as supraorbital
foramen) is an opening presented as a notch or a hole located on
each of the supraorbital margins of the frontal bone.
 The supraorbital notch or foramen is the passage for the
supraorbital artery and the lateral branch of the supraorbital
nerve.
 It is also a pressure point for the ophthalmic branch of the
trigeminal nerve.

10. The external surface
of the frontal bone
 A zygomatic process is a part of a bone which articulates with the
zygomatic bone.
 The zygomatic process of the frontal bone is an extension of
the frontal bone lateral to the orbit, and it is the process for
articulation with the zygomatic bone.
 The temporal line of the frontal bone is the continuation of the
line formed by the union of the superior and inferior temporal
lines of the parietal bone.
 A temporal surface of a bone is a part of a bone, which
contributes to the formation of the temporal fossa.
 The temporal surface of the frontal bone is the external, lateral
surface of the frontal bone, lateral from the temporal line of
the frontal bone, forming the anterosuperior part of the temporal
fossa.

11. The internal surface
of the frontal bone
The internal surface of the frontal bone features:
 frontal crest,
 groove for superior sagittal sinus.
The frontal crest is the median ridge on the internal surface of
the frontal bone for attachment of the falx cerebri.
The groove for the superior sagittal sinus is a shallow depression
on the frontal, parietal, and occipital bones forming a channel for
the sagittal superior sinus; its margins come together as it passes
downward and become continuous with the frontal crest.

12. Anatomical
views of the
Ethmoid bone

13. Dr. Aves Khan
Oral & Dental
Surgeon