Forehead

The forehead is a distinct anatomical region of the human head. It serves as a critical area for both physical protection and social communication. This region is defined by three specific boundaries. The top boundary is the hairline, which marks where scalp hair begins. The bottom boundary is the supraorbital ridge, a bony feature of the skull located above the eyes. The sides are defined by the temporal ridge, which connects the supraorbital ridge to the coronal suture line. Although eyebrows sit within this area, they are not considered part of the forehead itself. In the Latin-based Terminologia Anatomica, the forehead is referred to as the sinciput.

Underneath the skin, the forehead has a complex internal structure. The primary bone of this area is the squamous part of the frontal bone. Several muscles sit directly over this bone to allow for movement. These include the occipitofrontalis, the procerus, and the corrugator supercilii muscles. These muscles are controlled by the temporal branch of the facial nerve. To provide feeling, sensory nerves connect to the cervical plexus and the ophthalmic branch of the trigeminal nerve. These nerves reside within the subcutaneous fat. The blood supply to this region comes from several sources. These include the superorbital, supertrochealar, and anterior branches of the superficial temporal artery.

The nerves in the forehead work in very specific ways to provide sensation. The ophthalmic branch of the trigeminal nerve divides at the orbital rim into two distinct parts. The first part is known as the superficial division. This division runs over the surface of the occipitofrontalis muscle. It provides sensation for the skin of the forehead and the front edge of the scalp. The second part is called the deep division. This division runs directly into the occipitofrontalis muscle. This specific path provides sensation for the frontoparietal region.

Muscle movements in the forehead are essential for human expression. There are four basic motions that these muscles can perform. These motions can happen alone or combine to create complex looks. The occipitofrontalis muscles can raise the eyebrows either together or one at a time. This movement creates expressions of surprise or quizzicality. The corrugator supercilii muscles pull the eyebrows inward and downward to form a frown. Finally, the procerus muscles pull down the center portions of the eyebrows. These muscular actions also create characteristic wrinkles in the skin.

Wrinkles are a direct result of how these muscles move the skin. The occipitofrontalis muscles produce transverse wrinkles that run across the width of the forehead. In contrast, the corrugator supercilii muscles produce vertical wrinkles located between the eyebrows. These vertical lines sit just above the nose. The procerus muscles are responsible for causing the nose to wrinkle. Beyond these physical marks, the forehead can produce unusual sensations. In the middle of the forehead, people can experience a tactile hallucination. This is a tingling or pressure-like feeling that occurs when an object approaches the skin. This can happen without any actual physical contact. Even healthy individuals can feel this when seeing a finger or a pointed pencil move close to their forehead.

Historically, the shape of the forehead has been tied to ideas about human character. In the practices of physiognomy and phrenology, the forehead was thought to symbolize intelligence. In 1942, Samuel R. Wells noted that even highly intelligent animals have almost no forehead. He suggested that a diminished forehead was a sign of natural idiocy. Other historical figures had different views. Pseudo-Aristotle wrote in Physiognomica that the forehead is governed by the planet Mars. He believed different shapes indicated different traits. For example, a round forehead suggested virtue and good understanding. A long, high forehead was associated with honesty but also with weakness and poor fortune.

Many different forehead shapes were once used to categorize personality types. According to Pseudo-Aristotle, a low and small forehead showed boldness and confidence. A fleshy forehead without wrinkles was linked to vanity and deceit. A sharp forehead was thought to represent fickleness or weakness. A wrinkled forehead was seen as a sign of great wit, though it also suggested poor fortune. A full and large forehead could signify high spirit or malice. These historical beliefs show how much humans have observed this part of the body. Today, we understand the forehead through biology and neurology rather than through these ancient character studies.