Fox squirrel (Sciurus niger): The fox squirrel is the largest tree squirrel in Illinois, weighing one and three-quarters to two pounds with a length of 19 Â½ to 22 inches. The fur is a mix of rusty-yellow with black with an overall reddish cast. The fur on the ears, belly, and edge of the tail is lighter.
Audiologists are able to measure the speed and intensity of these pulses to determine if there is hearing loss or a lesion that is upsetting the flow of the sound information through the brainstem. This measurement is called a brainstem auditory evoked response (BAER).
Brainstem -- tegmentum not labeled, but is visible near center. [edit on Wikidata] The pontine tegmentum, or dorsal pons, is located within the brainstem, and is one of two parts of the pons, the other being the ventral pons or basilar part of the pons. The pontine tegmentum can be defined in contrast to the basilar pons: basilar pons contains the corticospinal tract running craniocaudally and can be considered the rostral extension of the ventral medulla oblongata; however, basilar pons is distinguished from ventral medulla oblongata in that it contains additional transverse pontine fibres that continue laterally to become the middle cerebellar peduncle.