Subthalamic nucleus
This structure within the basal ganglia innervates other structures, including a very important connection to the internal globus pallidus. The subthalamic nucleus essentially provides the excitement needed to drive the globus pallidus. Injury to this area or its efferent or afferent connections can induce this disorder contralateral to the side of the lesion. The structure itself is a regulator of motor function and is also involved in associative and limbic functions. It was traditionally thought that the disorder was only caused by injury to the subthalamic nucleus, but later studies have shown that damage to other basal ganglia regions can also be responsible for causing this disorder. Hemiballismus caused by lesions in the subthalamic nucleus is more severe than other forms of the disorder. Globus pallidus
From recent studies, it is now thought that hemiballismus can be associated with a decreased output of the globus pallidus. This is because studies have shown that firing rates decrease from 70/s to 40/s. In addition to a decreased firing rate, degenerative neurological disorders that cause patients to exhibit hemiballistic movements show a marked decrease in the globus pallidus mass as well. Increases in activity in this area causes there to be an inhibition of the motor thalamus. This causes cortical activation and thus a movement inhibition. In the case of hemiballismus, the opposite occurs, leading to the characteristic large, irregular movements.
Trichofolliculoma is a cutaneous condition characterized by a benign, highly structured tumor of the pilosebaceous unit. : 671

See also
Multiple familial trichoepithelioma
Pilomatricoma
Skin lesion
List of cutaneous conditions

References


== External links ==