Editing Cranial nerves (section)

==Development==

The cranial nerves are formed from the contribution of two specialized embryonic cell populations, [[cranial neural crest]] and ectodermal placodes. The components of the sensory nervous system of the head are derived from the neural crest and from an embryonic cell population developing in close proximity, the cranial sensory placodes (the olfactory, lens, otic, trigeminal, epibranchial and paratympanic placodes). The dual origin cranial nerves are summarized in the following table:<ref>{{Cite journal|last1=Méndez-Maldonado|first1=Karla|last2=Vega-López|first2=Guillermo A.|last3=Aybar|first3=Manuel J.|last4=Velasco|first4=Iván|date=2020-08-07|title=Neurogenesis From Neural Crest Cells: Molecular Mechanisms in the Formation of Cranial Nerves and Ganglia|journal=Frontiers in Cell and Developmental Biology|volume=8|page=635|doi=10.3389/fcell.2020.00635|pmid=32850790|pmc=7427511|issn=2296-634X|doi-access=free}}</ref>

'''Contributions of neural crest cells and placodes to ganglia and cranial nerves'''
{| class="wikitable"
! Cranial nerve
! Ganglion and type
! Origin of neurons
|-
|'''CNI – olfactory'''

(Ensheating glia of olfactory nerves)
|
|Telencephalon/olfactory  placode; NCCs at forebrain
|-
|'''CNIII – oculomotor'''

(m)
|Ciliary,  visceral efferent
|NCCs  at forebrain-midbrain junction (caudal diencephalon and the anterior  mesencephalon)
|-
|'''CNV – trigeminal'''

(mix)
|Trigeminal,  general afferent
|NCCs  at forebrain-midbrain junction (from r2 into 1st PA), trigeminal  placode
|-
|'''CNVII – facial'''

(mix)
|<nowiki>-Superior,  general and special afferent</nowiki>

-Inferior:  geniculate, general and special afferent

-Sphenopalatine,  visceral efferent

-Submandibular,  visceral efferent
|<nowiki>-Hindbrain  NCCs (from r4 into 2</nowiki><sup>nd</sup> PA), 1st epibranchial placode

-1st  epibranchial placode (geniculate)

-Hindbrain  NCCs (2nd PA)

-Hindbrain  NCCs (2nd PA)
|-
|'''CNVIII – Vestibulocochlear'''

(s)
|<nowiki>-Acoustic:  cochlear, special afferent; and vestibular, special afferent</nowiki>
|<nowiki>-Otic  placode and hindbrain (from r4) NCCs</nowiki>
|-
|'''CNIX – glossopharyngeal'''

(mix)
|<nowiki>-Superior,  general and special afferent</nowiki>

-Inferior,  petrosal, general and special afferent

-Otic,  visceral efferent
|<nowiki>-Hindbrain  NCCs (from r6 into 3</nowiki><sup>rd</sup> PA)

-2nd  epibranchial placode (petrosal)

-Hindbrain  NCCs (from r6 into 3rd PA)
|-
|'''CNX – vagus'''

(mix)

Superior  laryngeal branch; and recurrent laryngeal branch 
|<nowiki>-Superior,  general afferent</nowiki>

-Inferior:  nodose, general and special afferent

-Vagal:  parasympathetic, visceral efferent
|<nowiki>-Hindbrain  NCCs (from r7-r8 to 4</nowiki><sup>th</sup> & 6th PA)

-Hindbrain  NCCs (4th& 6th PA); 3rd (nodose) and 4th  epibranchial placodes

-Hindbrain  NCCs (4th & 6th PA)
|-
|'''CNXI – accessory'''

(m)
|No  ganglion *
|Hindbrain  (from r7-r8 to PA 4); NCCs (4th PA)
|}
Abbreviations: CN, cranial nerve; m, purely motor nerve; mix, mixed nerve (sensory and motor); NC, neural crest; PA, pharyngeal (branchial) arch; r, rhombomere; s, purely sensory nerve. * There is no known ganglion of the accessory nerve. The cranial part of the accessory nerve sends occasional branches to the superior ganglion of the vagus nerve.{{See also|List of foramina of the human body}}