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3D OSTEOLOGY
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FRONTAL BONE ANATOMY

Author: Dr. Bogdan Leahu
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Frontal bone anatomy 360-degree interactive viewer showing articulations with sphenoid, ethmoid, parietal, nasal, maxillae, lacrimal, and zygomatic bones
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TABLE OF CONTENTS

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GENERAL CHARACTERISTICS

  • Major cranial bone forming the forehead
  • Contributes to orbital roofs
  • Contributes to anterior cranial floor
  • Articulations:
    • Sphenoid bone
    • Ethmoid bone
    • Paired parietal bones
    • Paired nasal bones
    • Paired maxillae
    • Paired lacrimal bones
    • Paired zygomatic bones

SQUAMOUS PART

External surface of squamous part 360-degree viewer showing frontal eminences, superciliary arches, glabella, supraorbital margin, and forehead contour
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  • Vertical flattened region forming the forehead
  • External aspect is smooth and convex
  • Faces outward toward the scalp

Frontal Eminences

  • Paired rounded prominences
  • Located approximately 3 cm above supraorbital margin
  • Positioned on either side of midline
  • Contribute to forehead contour

Superciliary Arches

  • Paired elevations
  • Located directly above supraorbital margin
  • Accentuate brow prominence

Glabella

  • Smooth midline elevation
  • Situated between superciliary arches

Frontal Portion of Orbital Margin

  • Forms inferior boundary of squamous part

External Surface Features

  • Smooth convex surface
  • Forms visible forehead area
  • Supraorbital Notch or Foramen:
    • Located on medial aspect of supraorbital margin
    • Transmits neurovascular structures
  • Frontal Notch or Foramen:
    • Positioned medial to supraorbital notch
    • Provides passage for vessels and nerves
    • Supplies the forehead region

TEMPORAL SURFACE

Temporal surface of frontal bone 360-degree viewer showing zygomatic process, temporal line, parietal margin, and temple region contribution
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Temporal Surface of the Frontal Bone, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.

  • Lateral aspect of frontal bone
  • Contributes to temple region
  • Parietal Margin — posterior border
    • Articulates with parietal bones
  • Zygomatic Process — prominent lateral projection
    • Located at lateral end of supraorbital margin
    • Articulates with zygomatic bone
    • Forms part of lateral orbital wall
    • Forms part of orbital rim
  • Temporal Line:
    • Extends superiorly from zygomatic process
    • Extends posteriorly from zygomatic process
    • Divides into superior and inferior temporal lines
    • Attachment for temporalis muscle
    • Attachment for temporal fascia

INTERNAL SURFACE OF SQUAMOUS PART

Internal surface of squamous part 360-degree viewer showing frontal crest, foramen cecum, sagittal sulcus, and cranial cavity features
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Internal Surface of the Squamous Part, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.

  • Faces the cranial cavity
  • Frontal Crest — midline ridge
    • Formed by convergence of sagittal sulcus margins
    • Located at inferior midline
  • Foramen Cecum:
    • Located at inferior end of frontal crest
    • Formed by small notch uniting with ethmoid bone
    • Transmits small veins
    • Connects nasal cavity to superior sagittal sinus

NASAL PART

Nasal part of frontal bone 360-degree viewer showing nasal spine, nasal margin, and articulations with nasal bones and perpendicular plate of ethmoid
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Nasal Part of the Frontal Bone, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.

  • Inferior extension of frontal bone
  • Positioned between supraorbital margins
  • Nasal Spine — midline bony projection
    • Extends inferiorly from center of nasal part
    • Articulates with nasal bones
    • Articulates with perpendicular plate of ethmoid
  • Nasal Margin — inferior border
    • Articulates with superior borders of nasal bones
    • Contributes to nasal bridge formation

ORBITAL PART

Orbital part of frontal bone 360-degree viewer showing orbital plates, ethmoidal notch, trochlear fovea, fossa for lacrimal gland, and sphenoidal margin
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Orbital Part of the Frontal Bone, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.

  • Composed of two horizontal triangular plates called orbital plates
  • Forms orbital roofs
  • Forms anterior cranial fossa floor
  • Ethmoidal Notch — gap between orbital plates
    • Accommodates cribriform plate of ethmoid bone
  • Orbital Surface:
    • Inferior-facing aspect of each orbital plate
    • Directed into the orbit

Key Features of Orbital Surface

  • Trochlear Fovea — small medial depression
    • Located near nasal part
    • Attachment site for trochlea
    • Serves superior oblique muscle
  • Fossa for Lacrimal Gland — shallow depression
    • Located laterally
    • Houses the lacrimal gland
  • Sphenoidal Margin:
    • Articulates with greater wing of sphenoid bone
    • Completes anterior cranial fossa

FRONTAL SINUSES

Frontal sinuses 360-degree viewer showing paired irregular cavities, septum of frontal sinuses, drainage openings, and position superior to orbits
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  • Paired irregular cavities
  • Located within frontal bone
  • Positioned superior to orbits
  • Positioned posterior to superciliary arches
  • Septum of Frontal Sinuses — thin bony partition
    • Separates the two cavities
    • Variable position
    • Often results in asymmetrical sinuses
  • Drainage Openings:
    • Open into nasal cavity
    • Located on either side of nasal spine
    • Positioned anterior to ethmoidal notch
  • Functions:
    • Humidification of inspired air
    • Voice resonance enhancement
    • Reduction of skull weight

BIBLIOGRAPHY

1. Henry G, Warren HL. Osteology. In: Anatomy of the Human Body. 20th ed. Philadelphia: Lea & Febiger; 1918. p. 129–97.

QUICK FACTS: FRONTAL BONE

Key questions answered about this anatomy topic

Q: What is the frontal bone?

Answer: An unpaired bone forming the forehead and anterior cranial floor. The frontal bone is an unpaired cranial bone that forms the forehead, the roofs of the orbits, and the anterior portion of the cranial floor. It also contains the frontal sinuses.

Q: Where is the frontal bone located?

Answer: At the front of the skull, forming the forehead. The frontal bone is located at the front of the skull, forming the forehead. It extends from the coronal suture posteriorly to the orbits and nasal region anteriorly.

Q: What is the function of the frontal bone?

Answer: To protect the frontal lobes of the brain and form the orbital roofs. The frontal bone protects the frontal lobes of the brain, forms the roof of each orbit (eye socket), contributes to the anterior cranial fossa, and contains the frontal sinuses which help humidify air and reduce skull weight.

Q: How many frontal bones are there in the skull?

Answer: One (unpaired). There is one frontal bone in the adult skull. Although it develops from two halves separated by the metopic suture in infancy, these usually fuse by age 6-8 to form a single unpaired bone.

Q: Is the frontal bone a flat bone or an irregular bone?

Answer: Flat bone. The frontal bone is classified as a flat bone. It consists of two layers of compact bone (inner and outer tables) with cancellous bone (diploë) between them, characteristic of flat cranial bones.

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