Answer
The axons of the corticotubular tract terminate in the motor neurons of the pairs of nuclei of the following cranial nerves.
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII.Facial
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal
Work Step by Step
The axons of the corticotubular tract descend from upper motor neurons (UMNs) of the cortex, through the midbrain to synapse with lower motor neurons in the pons and the medulla. Some of these descending axons synapse and crossover (decussate) in the pons or the medulla, but some do not; in either case, they terminate in the motor neurons of the nuclei of the nine pairs of cranial nerves of the brain stem--cranial nerves III, IV, V, VI, VII, IX, X, XI, XII.
The function of this tract is coordinate precise voluntary movements of muscles of the eyes, of the tongue and of the neck. Muscles that carry out the process of of chewing and that form facial expression are also controlled through the corticotubular tract.
