Learning objectives:
At the end of this presentation, all the students should be able to:
The descending pathways are those routes through which motor signals are sent from brain to the body.
Anterior corticospinal tract:
The basal ganglia, brainstem, and cerebellum all receive strong motor signals from the corticospinal system every time a signal is transmitted down the spinal cord to cause a motor activity.
Damage to corticobulbar tract(upper motor neuron lesion)
- Due to the bilateral nature of this tract, a unilateral lesion usually results in mild muscle weakness.
- However, not all the cranial nerves receive bilateral input, and so there are a few exceptions which are;
Hypoglossal nerve :
A lesion to the upper motor neurones for CN XII will result in the deviation of the tongue to the contralateral side.
Facial nerve:
A lesion to the upper motor neurones for CN VII will result in spastic paralysis of the muscles in the
contralateral lower quadrant of the face.
