Medulla oblongata

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The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the

• an upper open part or superior part where the dorsal surface of the medulla is formed by the fourth ventricle.
• a lower closed part or inferior part where the fourth ventricle has narrowed at the
  central canal
  .

External surfaces

The

The region between the anterolateral and posterolateral sulcus in the upper part of the medulla is marked by a pair of swellings known as olivary bodies (also called olives). They are caused by the largest nuclei of the olivary bodies, the inferior olivary nuclei.

The posterior part of the medulla between the

Just above the tubercles, the posterior aspect of the medulla is occupied by a triangular fossa, which forms the lower part of the floor of the fourth ventricle. The fossa is bounded on either side by the inferior cerebellar peduncle, which connects the medulla to the cerebellum.

The lower part of the medulla, immediately lateral to the cuneate fasciculus, is marked by another longitudinal elevation known as the

Blood supply

Blood to the medulla is supplied by a number of

• Anterior spinal artery: This supplies the whole medial part of the medulla oblongata.
• Posterior inferior cerebellar artery: This is a major branch of the vertebral artery, and supplies the posterolateral part of the medulla, where the main sensory tracts run and synapse. It also supplies part of the cerebellum.
• Direct branches of the vertebral artery: The vertebral artery supplies an area between the anterior spinal and posterior inferior cerebellar arteries, including the solitary nucleus and other sensory nuclei and fibers.
• cuneate nucleus
  .

Development

The medulla oblongata forms in fetal development from the myelencephalon. The final differentiation of the medulla is seen at week 20 gestation.^{[4][full citation needed]}

Neuroblasts from the alar plate of the neural tube at this level will produce the sensory nuclei of the medulla. The basal plate neuroblasts will give rise to the motor nuclei.

• Alar plate neuroblasts give rise to:
  • The
    special visceral afferent
    column.
  • The spinal trigeminal nerve nuclei which contains the general somatic afferent column.
  • The
    special somatic afferent
    column.
  • The inferior olivary nucleus, which relays to the cerebellum.
  • The
    cuneate nuclei
    .
• Basal plate neuroblasts give rise to:
  • The
    general somatic efferent fibers
    .
  • The
    special visceral efferent
    .
  • The
    general visceral efferent fibers
    .

Function

The medulla oblongata connects the higher levels of the

• The
  dorsal respiratory group are neurons involved in this regulation. The pre-Bötzinger complex
  is a cluster of interneurons involved in the respiratory function of the medulla.
• Cardiovascular center – sympathetic, parasympathetic nervous system
• Vasomotor center – baroreceptors
• masseter reflex can be termed bulbar reflexes.^[5]

Lateral medullary syndrome can be caused by the blockage of either the posterior inferior cerebellar artery or of the vertebral arteries.

Progressive bulbar palsy (PBP) is a disease that attacks the nerves supplying the bulbar muscles. Infantile progressive bulbar palsy is progressive bulbar palsy in children.

Other animals

Both lampreys and hagfish possess a fully developed medulla oblongata.

• 
  Lobes
• 
  Cross section of the medulla (in red) and surrounding tissues.
• 
  Anteroinferior view

  of the medulla oblongata and pons.
• 
  Base of brain.
• 
  Diagram showing the positions of the three principal subarachnoid cisternæ.
• 
  Medulla oblongata
• 
  H&E-LFB stain

  .

References

This article incorporates text in the public domain from page 767 of the 20th edition of Gray's Anatomy (1918)

• Haycock DE (2011). Being and Perceiving. Manupod Press.
  ISBN 978-0-9569621-0-2
  .

External links

Wikimedia Commons has media related to Medulla oblongata.

• Stained brain slice images which include the "medulla" at the BrainMaps project