Structure and Function of the Facial Motor Nucleus
- The nucleus is located in the ventrolateral pontine tegmentum.
- Its axons form the motor component of the facial nerve.
- Neurons in the dorsal region innervate muscles of the upper face, while neurons in the ventral region innervate muscles of the lower face.
- The facial motor nucleus is part of the special visceral efferent (SVE) cell column.
- It innervates muscles derived from pharyngeal arches.
- It receives cortical input from the primary motor cortex.
- Upper motor neurons send axons that synapse on neurons in the facial motor nucleus.

Cortical Input to the Facial Motor Nucleus
- Cells of the facial motor nucleus receive cortical input from the primary motor cortex.
- Upper motor neurons descend through the internal capsule.
- Neurons in the dorsal aspect receive inputs from both sides of the cortex.
- Neurons in the ventral aspect mainly receive contralateral inputs.
- Both sides of the brain control the muscles of the upper face.

Clinical Significance of Facial Motor Nucleus Lesions
- An upper motor neuron lesion to fibers innervating the facial motor nucleus results in central seven.
- The syndrome is characterised by spastic paralysis of the contralateral lower face.
- A lower motor neuron lesion to the facial motor nucleus results in paralysis on the same side of the injury.
- Idiopathic palsy is the term used when the cause cannot be identified.
- Bells palsy is the term used when the cause is known.

Mechanism of Facial Nerve Upper vs Lower Motor Neuron Lesions
- Lesions within the corticobulbar tract are upper motor neuron lesions.
- Lesions affecting the individual branches are lower motor neuron lesions.
- The facial nerve branches leave the facial motor nucleus via different routes.
- The temporal branch receives motor input from both hemispheres.
- The zygomatic, buccal, mandibular, and cervical branches receive input from only contralateral hemispheres.

Additional Details about the Facial Motor Nucleus
- The nucleus has a dorsal and ventral region.
- Its axons travel dorsally and loop around the abducens nucleus.
- It is considered along with the trigeminal motor nucleus, nucleus ambiguus, and spinal accessory nucleus.

Facial motor nucleus (Wikipedia)

The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve (cranial nerve VII). These lower motor neurons innervate the muscles of facial expression and the stapedius.

Facial motor nucleus
Plan of the facial and intermediate nerves and their communication with other nerves. ("Nucleus of Facial N." labeled at upper left.)
Diagram of brain stem showing the nuclei of the cranial nerves
Details
Part of	Medulla oblongata
Artery	AICA
Vein	Anterior medullary
Identifiers
Latin	Nucleus nervi facialis
MeSH	D065828
NeuroNames	586
NeuroLex ID	birnlex_903
TA98	A14.1.05.412
TA2	5939
FMA	54572
Anatomical terms of neuroanatomy [edit on Wikidata]