Anterior median fissure of the medulla oblongata

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Brain: Anterior median fissure of the medulla oblongata
Section of the medulla oblongata at about the middle of the olive. (Anterior median fissure labeled at bottom center.)
Spinal cord (Ventral-median sulcus is "s4")
Latin	fissura mediana anterior medullae oblongatae
Gray's	subject #187 767
NeuroNames	hier-697
Dorlands/Elsevier	f_08/12365567

The anterior median fissure (ventral or ventromedian fissure) contains a fold of pia mater, and extends along the entire length of the medulla oblongata: it ends at the lower border of the pons in a small triangular expansion, termed the foramen cecum.

Its lower part is interrupted by bundles of fibers which cross obliquely from one side to the other, and constitute the pyramidal decussation.

Some fibers, termed the anterior external arcuate fibers, emerge from the fissure above this decussation and curve lateralward and upward over the surface of the medulla oblongata to join the inferior peduncle.

[edit] Additional images

Medulla oblongata and pons. Anterior surface.

Diagram showing the course of the arcuate fibers.

The formatio reticularis of the medulla oblongata, shown by a transverse section passing through the middle of the olive.

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

v • d • e Brain: rhombencephalon (hindbrain) Metencephalon/ pons Dorsal/ (tegmentum) surface: Locus ceruleus Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) cranial nuclei: GSA: Principal V/Spinal V - VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) - SVE: Motor V - VII - GSE: VI - GVE: VII: Superior salivary nucleus MLF, III, IV and VI (vestibulo-oculomotor fibers, medial vestibulospinal tract) sensory/ascending: Trapezoid body/VIII - Superior olivary nucleus Inferior cerebellar peduncle (Vestibulocerebellar tract) motor/descending: Apneustic center • Pneumotaxic center (Medial parabrachial nucleus) - Lateral parabrachial nucleus Ventral/ (base) Middle cerebellar peduncles (Pontocerebellar fibers) - Pontine nuclei motor/descending: Corticospinal tract - Corticobulbar tract - Corticopontine fibers Raphe/reticular Reticular formation (Caudal, Oral, Tegmental, Paramedian) • Raphe nuclei (Median) Myelencephalon/ medulla Dorsal surface: Posterior median sulcus - Postero-lateral sulcus - Area postrema cranial nuclei: GVA: VII,IX,X: Solitary/tract • SVA: Gustatory nucleus • GSE: XII  • GVE: IX,X,XI: Ambiguus • SVE: X: Dorsal • IX: Inferior salivatory nucleus - MLF, III, IV and VI sensory/ascending: Gracile nucleus • Cuneate nucleus (Accessory cuneate nucleus) • Sensory decussation  • Medial lemniscus motor/descending: Dorsal respiratory group Ventral motor/descending: Ventral respiratory group - Pyramid (Motor decussation) - Inferior olivary nucleus (Olivocerebellar tract, Rubro-olivary tract) surface: Anterior median fissure - Antero-lateral sulcus - Arcuate nucleus of medulla - Olivary body Raphe/reticular Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) • Raphe nuclei (Obscurus, Magnus, Pallidus)