The glabella is a medical term given to the space on the human head that is located above the nose and between the eyebrows. This area of the head sits just over the frontal bone of the skull and works to connect the two structures known as superciliary ridges. The word glabella translates to "smooth" from the original Latin. This is because this area tends to be hairless.
The superciliary ridges, which are joined together by the glabella, are also referred to as the superciliary arches. These structures are prominent elevations found on the frontal bone. In humans, these arches tend to be more pronounced and prominent in men than in women. Interestingly, this feature is even more pronounced in monkeys than they are in humans.
The glabella becomes important when a medical professional tests a patient for conditions such as dehydration. Skin turgor, or pressure and tension, can be measured using the glabella. This test measures the pressure of the cell contents. This pressure decreases when a person is dehydrated. Dehydration will cause this area shrivel and begin to wrinkle.
The glabellar reflex, also referred to as the glabellar tap sign, is measured at the glabella as well. This is one of the reflexes that is considered a primitive reflex, or a reflex present in newborns that disappears by adulthood. Some medical conditions, such as cerebral palsy, may cause these reflexes to remain into older childhood or even adulthood. Other medical conditions, including strokes, brain trauma, and dementia, can sometimes cause these primitive reflexes to return in adulthood.
The glabella reflex is tested by tapping on the forehead in the location of the glabella. The first few taps to this area will cause the patient to blink. If the blinking continues after the first few taps, this is considered an abnormal response. The clinical name for this abnormal response is Myerson's sign. This response is particularly common in the earliest stages of Parkinson's Disease.
In addition to Parkinson's Disease, early stages of dementia can sometimes cause an abnormal glabella reflex. Other progressive neurological conditions can also lead to Myerson's sign when the glabella is tapped. It is important to report any changes in neurological function to a medical professional so proper testing can be performed. Early detection of neurological disorders can help a patient have a better overall quality of life.