Forehead Bone
Os Frontale
location_on Anterior cranium, forming the forehead and superior orbital margins
The frontal bone forms the forehead, the roofs of the orbits, and most of the anterior cranial fossa. It contains the frontal sinuses, paired air-filled cavities that lighten the skull and add resonance to the voice. The bone articulates with 12 other bones, more than any other cranial bone.
Key Anatomical Features
- Frontal sinuses are paired cavities between inner and outer tables of bone
- Supraorbital foramen transmits the supraorbital nerve and vessels
- Glabella is the smooth midline prominence between the superciliary arches
- Orbital plates form the roof of each orbit and the floor of the anterior cranial fossa
- Metopic suture may persist as a variant in about 8% of adults
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Frontalis | Frontal belly inserts into skin of eyebrow region | Raises the eyebrows and wrinkles the forehead |
| Orbicularis oculi | Medial orbital margin | Closes the eyelids |
| Corrugator supercilii | Medial superciliary arch | Draws eyebrows medially, producing vertical wrinkles |
| Temporalis | Temporal surface of frontal bone | Elevates and retracts the mandible |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Coronal suture | Fibrous suture | Parietal bones |
| Frontozygomatic suture | Fibrous suture | Zygomatic bone |
| Frontonasal suture | Fibrous suture | Nasal bones |
Common Pathologies
Frontal sinus fracture
Fractures of the anterior table may cause cosmetic deformity, while posterior table fractures risk cerebrospinal fluid leaks and intracranial infection.
Frontal sinusitis
Infection of the frontal sinuses causing pain above the eyes, which can rarely spread to the brain causing epidural abscess or meningitis.
Craniosynostosis (metopic)
Premature fusion of the metopic suture causing trigonocephaly, a triangular forehead shape visible from above.
Clinical Relevance
Frontal bone fractures require CT imaging to evaluate both anterior and posterior tables. Posterior table fractures carry risk of CSF leak and require neurosurgical consultation. The frontal sinuses do not develop until around age 6, so pediatric frontal fractures differ significantly from adult patterns.
Development and Ossification
The frontal bone develops from two halves joined by the metopic suture, which typically fuses by age 2. Ossification begins intramembranously during the 8th fetal week from a single center on each side.
Did You Know?
- The frontal bone is the only cranial bone that contains a significant sinus cavity
- Frontal sinuses are as unique as fingerprints and have been used for forensic identification
- In some ancient cultures, intentional cranial deformation targeted the frontal bone to achieve elongated skull shapes
Scan this bone yourself
Download Osteo+ and identify the forehead bone instantly with your camera. Get all the details above and more from a single photo.