NETTER - Neuroscience Flash Cards

Distribution of Lower Motor Neurons
(LMNs) in the Brain Stem
1. Oculomotor nucleus
2. Trochlear nucleus
3. Trigeminal motor nucleus
4. Abducens nucleus
5. Facial nucleus
6. Nucleus ambiguus
7. Hypoglossal nucleus
8. Spinal accessory nucleus
9. Spinal cord ventral horn LMNs
Comment: Lower motor neurons (LMNs) are found in a medial
column and a lateral column in a longitudinal view of the brain stem.
The medial column consists of the extraocular nuclei (oculomotor,
trochlear, abducens nuclei) and the hypoglossal nucleus, all derived
from the general somatic efferent system. The lateral column
consists of the trigeminal motor nucleus, facial nucleus, nucleus
ambiguus, and spinal accessory nucleus, all derived from the special
visceral efferent system. All of these nuclei contain classical LMNs
with axonal connections leaving the CNS and terminating with
neuromuscular junctions on skeletal muscle fibers. The LMNs of the
spinal cord are found at every level in clusters in the ventral horn,
with the proximal extremities and trunk represented more medially
and the distal musculature represented more laterally and dorsally.
Systemic Neuroscience See book 15.3