The human skull is a complex structure made up of 22 bones, designed primarily to protect the brain and provide a framework for the face. The forehead is formed by a single, unpaired bone that represents a significant portion of both the cranial and facial architecture. This foundational element defines the upper face and shields the brain’s anterior region.
The Name and Position of the Forehead Bone
The bone that creates the forehead is scientifically known as the Frontal Bone. Its name is derived from the Latin word frons, which translates to “forehead.” This flat, bowl-shaped bone forms the anterosuperior, or front-upper, part of the cranium.
It is positioned superiorly to the nasal bones and anteriorly to the two parietal bones, which form the sides and roof of the skull. The posterior boundary is marked by the coronal suture, where it firmly joins the parietal bones. Its inferior border extends to form the upper ridge and roof of the orbital cavities, commonly called the eye sockets. It also articulates with the sphenoid and ethmoid bones deeper within the skull.
Internal Structure and Key Landmarks
The frontal bone consists of a large, convex surface that forms the curve of the forehead, known as the squamous part. Internally, it features a layer of spongy bone, called diploë, sandwiched between thin layers of compact bone.
Within this structure are the Frontal Sinuses, which are paired, air-filled cavities located deep to the brow ridges. These sinuses are lined with a mucous membrane and connect to the nasal cavity. They are thought to decrease the skull’s weight and contribute to voice resonance.
On the external surface, two prominent landmarks are the Supraorbital Margins, which are the thickened ridges defining the upper border of the eye sockets. The smooth area between these margins, located above the nose, is called the Glabella.
Primary Functions and Protective Roles
The primary role of the frontal bone is the physical protection of the brain’s frontal lobes. Its hard, mineral matrix acts as a substantial barrier against external force.
Beyond brain protection, the bone provides structural support to the upper face. It forms the bony roof of the orbits, shielding the eyes and their accessory structures.
The frontal bone also serves as an anchor point for several muscles of facial expression, including the frontalis muscle, which is responsible for raising the eyebrows. By supporting these soft tissues and defining the upper facial contour, the frontal bone contributes significantly to the overall shape and integrity of the head.