Rhombencephalon

Brain: Rhombencephalon
Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures.
Scheme of roof of fourth ventricle.
Gray's	subject #187 767
NeuroNames	hier-531
MeSH	Rhombencephalon
NeuroLex ID	birnlex_942

The rhombencephalon (or hindbrain) is a developmental categorization of portions of the central nervous system in vertebrates.

The rhombencephalon can be subdivided in a variable number of transversal swellings called rhombomeres. In the human embryo eight rhombomeres can be distinguished, from caudal to rostral: Rh7-Rh1 and the isthmus (the most rostral rhombomere).

A rare disease of the rhombencephalon, "rhombencephalosynapsis," is characterized by a missing vermis resulting in a fused cerebellum. Patients generally present with cerebellar ataxia.

The caudal rhombencephalon has been generally considered as the initiation site for neural tube closure.^[1]

Contents 1 Myelencephalon 2 Metencephalon 3 Evolution 4 Additional images 5 References 6 External links

Myelencephalon

Rhombomeres Rh7-Rh4 form the myelencephalon.

The myelencephalon forms the medulla oblongata in the adult brain; it contains:

• a portion of the fourth ventricle,
• the glossopharyngeal nerve (CN IX),
• vagus nerve (CN X),
• accessory nerve (CN XI),
• hypoglossal nerve (CN XII),
• and a portion of the vestibulocochlear nerve (CN VIII).

Metencephalon

Rhombomeres Rh3-Rh1 form the metencephalon.

The metencephalon is composed of the pons and the cerebellum; it contains:

• a portion of the fourth ventricle,
• the trigeminal nerve (CN V),
• abducens nerve (CN VI),
• facial nerve (CN VII),
• and a portion of the vestibulocochlear nerve (CN VIII).

Evolution

The hindbrain is homologous to a part of the arthropod brain known as the sub-oesophageal ganglion.^[2] On this basis, it has been suggested that the hindbrain first evolved in the Urbilaterian - the last common ancestor of chordates and arthropods - between 570 and 555 million years ago.^[2][3]

Additional images

References

• Haycock DE (2011). Being and Perceiving. Manupod Press. ISBN 9780956962102. http://books.google.co.uk/books?id=fXFeQb1z6bsC. 

1. ^ SpringerLink - Journal Article
2. ^ ^{a b} Ghysen A (2003). "The origin and evolution of the nervous system". Int. J. Dev. Biol. 47 (7–8): 555–62. PMID 14756331. http://www.ijdb.ehu.es/web/paper.php?doi=14756331. 
3. ^ Haycock, DE Being and Perceiving

External links

• NIF Search - Rhombencephalon via the Neuroscience Information Framework

Nervous system (TA A14, GA 9) Central nervous system Meninges Spinal cord Brain: Rhombencephalon (Medulla oblongata, Pons, Cerebellum) • Mesencephalon • Prosencephalon (Diencephalon, Telencephalon) Peripheral nervous system Somatic Sensory nerve • Motor nerve • Cranial nerve • Spinal nerve Autonomic Sympathetic • Parasympathetic • Enteric nervous system M: CNS anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D) M: PNS anat(h/r/t/c/b/l/s/a)/phys(r)/devp/prot/nttr/nttm/ntrp noco/auto/cong/tumr, sysi/epon, injr proc, drug(N1B)

Human brain: rhombencephalon, myelencephalon: medulla (TA A14.1.04, GA 9.767) Dorsal Surface Posterior median sulcus · Posterolateral sulcus · Area postrema · Vagal trigone · Hypoglossal trigone · Medial eminence Grey: Cranial nuclei afferent: GVA: VII,IX,X: Solitary/tract/Dorsal respiratory group · SVA: Gustatory nucleus · GSA: VIII-v (Lateral, Medial, Inferior) efferent: GSE: XII  · GVE: IX,X,XI: Ambiguus · SVE: X: Dorsal · IX: Inferior salivatory nucleus Grey: other Gracile nucleus · Cuneate nucleus · Accessory cuneate nucleus White: Sensory/ascending Sensory decussation  · Medial lemniscus · Inferior cerebellar peduncle (Juxtarestiform body) · Ascending dorsal longitudinal fasciculus · MLF, III, IV and VI White: Motor/descending Descending dorsal longitudinal fasciculus · MLF, III, IV and VI Ventral White: Motor/descending Motor decussation · Olivocerebellar tract · Rubro-olivary tract Grey matter Ventral respiratory group · Arcuate nucleus of medulla · Inferior olivary nucleus · Rostral ventromedial medulla Surface Anterior median fissure · Anterolateral sulcus · Olive · Pyramid Grey: Raphe/ reticular Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) · Raphe nuclei (Obscurus, Magnus, Pallidus) M: CNS anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101–604, GA 9.785) Dorsal/ (tegmentum) Surface Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus White: Sensory/ascending Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus MLF, III, IV and VI: Vestibulo-oculomotor fibers Anterior trigeminothalamic tract · Central tegmental tract White: Motor/descending ICP (Vestibulocerebellar tract) MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract) Grey: Cranial nuclei afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Superior) efferent: SVE: Motor V  · VII · GSE: VI · GVE: VII: Superior salivary nucleus Other grey Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus Ventral/ (base) Grey Pontine nuclei White: Motor/descending Corticospinal tract · Corticobulbar tract · Corticopontine fibers MCP (Pontocerebellar fibers) Surface Basilar sulcus Other grey: Raphe/ reticular Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median) M: CNS anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

Ventricular system, rhombencephalon, met- and myel-: fourth ventricle (TA A14.1.05.701–726, GA 9.797) Roof (dorsal) rostral: Superior medullary velum (Frenulum) caudal: Inferior medullary velum · Taenia of fourth ventricle Floor/rhomboid fossa (ventral) rostral (pons): Facial colliculus · Locus coeruleus caudal (medulla}: Vagal trigone · Hypoglossal trigone · Area postrema · Obex Medial eminence · Sulcus limitans Apertures Median/Magendie · Lateral recess to Lateral/Luschka Other Tela chorioidea of fourth ventricle · Fastigium M: CNS anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

Human brain, rhombencephalon, metencephalon: cerebellum (TA 14.1.07, GA 9.788) Surface anatomy Lobes Anterior lobe · Posterior lobe (Horizontal fissure) · Flocculonodular lobe (Flocculus, Nodule) Primary fissure Medial/lateral Vermis: anterior (Central lobule, Culmen, Lingula) · posterior (Folium, Tuber, Uvula) · Vallecula of cerebellum Hemisphere: anterior (Alar central lobule) · posterior (Biventer lobule, Cerebellar tonsil) Grey matter Deep cerebellar nuclei Dentate · interposed (Emboliform, Globose) · Fastigial Cerebellar cortex Molecular layer (Stellate cell, Basket cell) Purkinje cell layer (Purkinje cell, Bergmann glia cell = Golgi epithelial cell) Granule cell layer (Golgi cell, Granule cell, Unipolar brush cell) Fibers: Mossy fibers · Climbing fiber · Parallel fiber White matter Internal Arbor vitae Peduncles Inferior (medulla): Dorsal spinocerebellar tract · Olivocerebellar tract · Cuneocerebellar tract · Juxtarestiform body (Vestibulocerebellar tract) Middle (pons): Pontocerebellar fibers Superior (midbrain): Ventral spinocerebellar tract · Dentatothalamic tract · Trigeminocerebellar fibers M: CNS anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D)