Metencephalon

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Brain: Metencephalon

Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures.

Pons and cerebellum.
Gray's	subject #187 785
NeuroNames	hier-534
MeSH	Metencephalon
Dorlands/Elsevier	m_12/12529123

The metencephalon is a developmental categorization of portions of the central nervous system. The metencephalon is composed of the pons and the cerebellum; contains a portion of the fourth ventricle; and the trigeminal nerve (CN V), abducens nerve (CN VI), facial nerve (CN VII), and a portion of the vestibulocochlear nerve (CN VIII).

v • d • e Brain: rhombencephalon (hindbrain)
Myelencephalon/medulla	anterior/ventral: Arcuate nucleus of medulla • Pyramid (Decussation) • Olivary body • Inferior olivary nucleus • Anterior median fissure • Ventral respiratory group posterior/dorsal: VII,IX,X: Solitary/tract • XII, X: Dorsal • IX,X,XI: Ambiguus • IX: Inferior salivatory nucleus • Gracile nucleus/Cuneate nucleus/Accessory cuneate nucleus • Area postrema • Posterior median sulcus • Dorsal respiratory group raphe/reticular: Sensory decussation • Reticular formation (Gigantocellular nucleus, Parvocellular reticular nucleus, Ventral reticular nucleus, Lateral reticular nucleus, Paramedian reticular nucleus) • Raphe nuclei (Obscurus, Magnus, Pallidus) tracts: Corticospinal tract (Lateral, Anterior) • Inferior cerebellar peduncle • Olivocerebellar tract • Spinocerebellar (Dorsal, Ventral) • Spinothalamic tract • PCML (Posterior external arcuate fibers, Internal arcuate fibers, Medial lemniscus) • Extrapyramidal (Rubrospinal tract, Vestibulospinal tract, Tectospinal tract)
Metencephalon/pons	anterior/ventral: Superior olivary nucleus • Basis pontis (Pontine nuclei, Middle cerebellar peduncles) posterior/dorsal: Pontine tegmentum (Trapezoid body, Superior medullary velum, Locus ceruleus, MLF, Vestibulocerebellar tract, V Principal Spinal & Motor, VI, VII, VII: Superior salivary nucleus) • VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) raphe/reticular: Reticular formation (Caudal pontine reticular nucleus, Oral pontine reticular nucleus, Tegmental pontine reticular nucleus, Paramedian pontine reticular formation) • Median raphe nucleus Apneustic center • Pneumotaxic center
Metencephalon/cerebellum	Vermis • Flocculus • Arbor vitae • Cerebellar tonsil • Inferior medullary velum Molecular layer (Stellate cell, Basket cell, Parallel fiber) • Purkinje cell layer (Purkinje cell) • Granule cell layer (Golgi cell) • Mossy fibers • Climbing fiber Deep cerebellar nuclei (Dentate, Emboliform, Globose, Fastigial)
Fourth ventricle	apertures (Median, Lateral) • Rhomboid fossa (Vagal trigone, Hypoglossal trigone, Obex, Sulcus limitans, Facial colliculus, Medial eminence) • Lateral recess