Barognosis is the ability to perceive and evaluate the
weight of objects (e.g., by looking at them) or to tell the
difference between objects of different weights
(especially those held in the hands). Sensory
information about weights is transmitted by a part of the
spinal cord known as the posterior column-medial
lemniscus (PCML) pathway. This is a nerve pathway
consisting of fast conducting fibers surrounded by a
The pathway transmits sensory information up the posterior column (back section) of the
spinal cord and from the medial lemniscus of the brainstem. The brainstem is an area in
the lower part of the brain that connects it with the spinal cord. The medial lemniscus is a
nerve pathway in the brainstem that carries sensory information to a sensory relay
station in the brain known as the thalamus.
Barognosis is tested by placing a small weighted object in each hand and asking the
patient which hand contains the heavier weight. The weight s can be the same size and
then modified so one weight is heavier than the other. Alternatively, two weights can be
placed in the same hand and the patient can be asked which weight is heavier. Another
technique is to have the patient pick up a series of weights with the fingertips and state
which one is heavier. Bargnosis is also known as baresthesia. The opposite of
barognosis is baragnosis, which is the inability to evaluate the weight of objects.
Barognosis comes from the Greek word "baros" meaning "weight," and the Greek word
"gnosis" meaning "knowledge." Put the words together and you have "weight knowledge."
Weighing objects by hand.