Question

The corticobulbar pathway synapses with lower motor neurons in nuclei of which cranial nerves? select all that apply.

a) II
b) III
c) IV
d) V
e) VI
f) VII
g) VIII
h) IX
i) XI
j) XII
k) all of these

Answer 1

The corticobulbar pathway synapses with lower motor neurons in the nuclei of cranial nerves III (Oculomotor), IV (Trochlear), V (Trigeminal), VI (Abducens), VII (Facial), IX (Glossopharyngeal), XI (Accessory), and XII (Hypoglossal). It does not synapse with cranial nerves II (Optic) or VIII (Vestibulocochlear).

Step-by-step explanation:

The corticobulbar pathway is involved in the control of voluntary movements of muscles that are innervated by cranial nerves. This pathway synapses with lower motor neurons in the nuclei of certain cranial nerves. Specifically, the corticobulbar tract synapses with lower motor neurons in the nuclei of:

• III - Oculomotor
• IV - Trochlear
• V - Trigeminal
• VI - Abducens
• VII - Facial
• IX - Glossopharyngeal
• XI - Accessory (Note: this is sometimes grouped under the corticospinal tract as it primarily innervates neck muscles)
• XII - Hypoglossal

Therefore, the corticobulbar pathway does not synapse with the lower motor neurons in the nuclei of cranial nerves II (Optic) or VIII (Vestibulocochlear), which are not typically involved in motor control. In terms of this specific question, the corticobulbar pathway synapses with lower motor neurons in the nuclei of cranial nerves III (Oculomotor), IV (Trochlear), V (Trigeminal), VI (Abducens), VII (Facial), IX (Glossopharyngeal), XI (Accessory; with some qualifications), and XII (Hypoglossal).