Cranial nerves: general introduction Anna L. Kiss Department of Human Morphology and Developmental Biology Semmelweis University Budapest 2014

Cranial nerves olfactory n. (I) ptic chiasam (II) optic tract (II) oculomotory n. (III) trochlear n. (IV) trigeminal n. (V) facial n. (VII) vestibulocochlear n. (VIII) glossopharyngeal n.+vagus (IX, X) accessory n. (XI) abducens n. (VI) hypoglossal n. (XII)

Olfactory nerve (I): is developing as an early part of the primitive Olfactory nerve (I): is developing as an early part of the primitive telencephalon Optic nerve (II): is developing as an outpouching from the diencephalon Carnial nerves III to XII: originate from the brain stem are embryologically homologous with spinal nerves nuclei of them derived originally from cell columns homologous with the columns of the spinal cord

Cranial nerves Functionally: Visceral (vegetative): autonom, unvoluntary Somatic: voluntary Sensory: about the outside world; structures developed from embryonic ectoderm and somatic mesoderm Motory: controlling voluntary muscles, derived from somites and embryonic gill arches Motory: controlling function of the viscera (symphatetic and parasymphatetic) Sensory: viscera developed from ectoderm and splanchnic mesoderm somatic efferent SE general somatic afferent GSA visceral efferent VE general visceral afferent GVS

Spinal nerves: mixed (sensory, motor sometimes vegetative fibers) radix posterior ganglion spinale nervus spinalis radix anterior

Cranial nerves Motor nerves: IV, VI, XII – somatomotor III – somatomotor, visceromotor Sensory: VIII – special (hearing, balance) Mixed: V, VII, IX, X - sensory, motor + vegetatíve (exept: V) Special motor: XI (motoros – spinal fibers) Not really cranial nerves: I, and II – outgrowth of the central nervous system

Nuclei of the cranial nerves in the brainstem III. IV: midbrain V. VI. és VII. motor nuclei: pons V. : 3 sensory nuclei: midbrain, pons and medulla VIII.: at the border of the pons and medulla IX. X. XI. XII: medulla Motor nuclei: perikaryons of the „low” motoneurons Sensory nuclei: perikaryons of the second ordered neurons (primary sensory neurons: outside the brainstem, ganglions (similarly to gg. spinale)

Development of the spinal cord somatosensor (afferens) visceral somatomotor (efferens)

Spinal cord versus brainstem

Grey matter in the brainstem mesencephalon pons medulla „open” part medulla „closed” part

Reorganizationof the central grey matter at the brainstem Spinal cord medulla (closed part) medulla (open part) mesencephalon medulla-pons pons (at the level of locus a locus ceruleus)

Special Visceral Efferent: SVE Somatosensor Viscerosensor Visceromotor Somatomotor Ventrolateral Somatomotor Visceromotor Special Visceral Efferent: SVE Brachiomotor nn. V, VII, IX, X, XI Branchial arches

Cranial nerves of the branchial arches

General/Special Viscerlal Afferent GVA, SVA Viscerosensoros General/Special Viscerlal Afferent GVA, SVA Somatosensoros General/Special Somatic Afferent GSA, SSA Visceromotoros General Visceral Efferent: GVE parasympathicus Ventrolateral collumn Somatomotor? Visceromotor? Special Visceral Efferent: SVE Brachiomotor nn. V, VII, IX, X, XI Nerves of the branchial arches Dorsomedial collumn Pure motor nuclei nn. III, IV, VI, XII Somatomotor General Somatic Efferent: GSE

Development of the brainstem 3. Cell types: branchial afferens and efferens innervation of the derivatives of the branchial arches: V., VII., IX., X. speciális special visceral: branchial (SSA) general visceral (GSA)

Nuclei of the cranial nerves at the rhomboid fossa viscero- and branchiosensory (taste) somatosensory (n. trigeminus) speciál somatosensory (vestibulocochlear) IV. ventricle – rhomboid fossa visceromotory (viscera, glands, heart parasympathetic) branchiomotory (muscles of the branchial arches) somatomotory (muscles of the tongue)

Motor (efferens) nuclei in the brainstem Muscles of the head, orbit, tongue: n. oculomotorius (III) n. trochlearis (IV) n. abducens (VI) n. hypoglossus (XII) Pharynx, m. of mastication, m. of the face, larynx: derivatives of the branchial arches: n. trigeminus: motor nucleus n. facialis: motor nucleus n. glossopharyngeus n. vagus Visceralis (parasympathetic): Edinger-Westfal (III) n. salivatorius (VII., IX) n. dorsalis n. vagi close to the midline lateral n. ambiguus farest from the midlinef

Sensory (afferens) nuclei in the brainstem n. tractus solitarii: VII., IX., X.: visceral + branchiali afferens nuclei: taste+visceral afferens from heart, lung main sensory n. trigeminus n. tractus spinalis n. trigemini n. mesencephalius n. trigemini Special somatosensory nuclei: n. cochlearis n. vestibularis somatosensor

nucl. princeps sensorius n. V medulla: „open” (rostral) part nucl. motorius n. V nucl. princeps sensorius n. V nucl. tractus spinalis n. V pons N. trigeminus medulla: „closed” (caudal) part

nucl. princeps sensorius n. V nucl. tractus solitarii somatosensor sup. salivatory n. visceromotor nucl. tractus spinalis n. V nucl. tractus solitarii viscerosensor nucl. motorius n. VII somatomotor N. facialis

N. glossopharyngeus nucl. princeps sensorius n. V somatosensor nucl. tractus spinalis n. V. somatosensor inf. salivatory nucl. visceromotor nucl. tractus solitarii viscerosensor nucl. ambiguus somatomotor N. glossopharyngeus

N. vagus nucl. princeps sensorius n. V somatosensor nucl. tractus solitarii (ala cinerea lat.) (viscerosensor) nucl. dorsalis n. X (ala cinerea med.) visceromotor nucl. tractus spinalis n. V somatosensor nucl. tractus solitarii viscerosensor nucl. ambiguus somatomotor N. vagus

References Szentagothai J, Réthelyi M: Funkcionális anatómia Sobota - Atlas of Human Anatomy, 20th edition, Urban and Schwarzenberger, 1993 Stephen Goldberg: Clinical neuroanatomy, 1998