Anatomy · Bones

Frontal bone

The forehead bone

Skull · cranium

The frontal bone is a single, shell-shaped bone that forms the forehead and the roof of both eye sockets. It is one of the eight bones of the cranium and protects the front of the brain. Its name comes from the Latin frons, meaning forehead.

How to spot them

▸A curved, unpaired plate at the front of the cranium, forming the forehead and the upper rim and roof of each orbit
▸Joined to the two parietal bones behind it along the coronal suture
▸Has a hollow air space (a sinus) above each eyebrow, and a small notch or foramen on the upper orbital rim for a sensory nerve
▸Its smooth midline patch between the eyebrows is the glabella

What to know

The single bone that forms the forehead and the roof of both eye sockets

Frontal bone — unpaired, shell-shaped, at the anterosuperior part of the cranium.

It meets the two bones behind it at the coronal suture, and the point where that suture meets the sagittal suture is called the bregma

Frontal bone — the coronal suture joins it to the paired parietal bones.

The smooth, slightly depressed area between the eyebrows on this bone is called the glabella

Frontal bone — the glabella lies at the anterior midline.

A hollow air space in this bone, above the eyes, can become infected and, untreated, spread to the orbit or the meninges

Frontal bone — it houses the frontal sinuses.

A foramen on the upper rim of the orbit in this bone carries a nerve and vessels to the skin of the forehead

Frontal bone — the supraorbital foramen (or notch).

In an infant this bone is in two halves separated by the metopic suture, which normally fuses in early childhood

Frontal bone — the metopic suture may persist into adulthood in a minority of people.

A cartilaginous pulley for the superior oblique eye muscle attaches to a small fossa on the underside of this bone

Frontal bone — the trochlear fossa, on the orbital part.

Key ideas

It has four parts: the large squamous part (the forehead itself), two orbital parts (the roofs of the orbits) and a small nasal part between the eyebrows that articulates with the nasal bones.
On its inner surface a midline groove, the sagittal sulcus, holds the superior sagittal sinus, and the frontal crest anchors the falx cerebri.

Quick-fire facts

•One of the 8 bones of the cranium: the unpaired frontal, occipital, sphenoid and ethmoid, plus the paired parietal and temporal bones
•Articulates with twelve other bones: ethmoid and sphenoid (unpaired), and nasal, maxilla, lacrimal, parietal and zygomatic (paired)
•The frontal sinuses are separated by a septum and sit above the orbits either side of the midline
•The frontal sinus is the most anterior of the paranasal sinuses
•The eyebrow ridges (superciliary arches) sit on this bone and are generally more prominent in males
•The pterion, the H-shaped weak point on the side of the skull, is where the frontal, parietal, temporal (squamous part) and sphenoid (greater wing) bones meet
•Fractures through the back wall of the frontal sinus can tear the dura and cause a leak of cerebrospinal fluid from the nose
•Latin frons (forehead) gives the adjective frontal, and the frontal lobe of the brain lies beneath the bone

Drill it — 8 cards

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Sources

TeachMeAnatomy — The Frontal Bone
OpenStax — Anatomy and Physiology 2e, 7.2 The Skull