Medulla oblongata


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The medulla is the lowest part of the brain stem and the brain itself. It is divided into two main parts


 Medulla which is also called the open medulla.


Lower medulla also called the closed medulla.

 The open medulla is so called because it opens into the fourth ventricle. The 4th ventricle is placed at its back. The closed medulla is so called because it is closed with a central canal within its substance just as you have in the spinal cord. The closed medulla is closed because it has the central canal of the medulla buried in its middle. 

The medulla has at its ventral surface, the pyramids on the two sides of the anteromedian sulcus. Lateral to the pyramids are the olivo-pyramidal interval which form  sulci for the escape of rootlets of the hypoglossal nerve. Lateral to the olive is the  postolivary sulcus and it carries the rootlets of cranial nerves 9, 10 and 11- glossopharyngeal, vagus and accessory nerves.

Posterior aspect of the medulla has the tuberculum gracilis most lateral to the posteromedian fissure and lateral to it is the tuberculum cuneatus. The two tubercula have buried in them the nuclei gracilis and cuneatus respectively. At the back of the upper medulla is the 4th ventricle. It is covered at the back of the medulla by the inferior medullary velum and tela choroidea. The floor of the 4th ventricle is called the rhomboid fossa.

The medulla is made up of the following parts


Medullary reticular formation






4th ventricle, at its back


Axial MRI showing medulla

Dissect brainstem


Practical (PaL-Weigert)


Closed medulla

  Tuberculum gracilis

  Nucleus gracilis

  Tuberculum cuneatus

   Nucleus cuneatus

   Accessory cuneate nucleus

    Internal arcuate fibers


   Rhomboid fossa


   Inferior olivary nuclear complex

   Medullary reticular formation

       Nucleus reticularis gigantocellularis

   Pyramidal tract

Open medulla

  Fourth ventricle

  Hypoglossal trigone

  Hypoglossal nucleus

  Hypoglossal nucleus

  Inferior medullary velum

  Tela choroidea

  Tractus solitarius

  Nucleus of tractus solitarius

  Vagal trigone

  Rhomboid fossa

  Median sulcus

  Accessory nerve root

  Vagal nucleus

  Nucleus ambiguus

  Dorsal nucleus of vagus

  Inferior salivatory nucleus

  Glossopharyngeal root

  Glossopharyngeal functional components

  Vestibular nuclei

  Cochlear nuclei

  Spinal nucleus and tract of V

   Calamus scriptorius


   Area postrema



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Electronic School of Medicine
Creator: Oluwole Ogunranti

Medulla in Scene 5 DIGITAL LOCATOR OF MEDULLA: Layer1-DIGITAL LOCATOR OF BRAINSTEM: Scene 1-Brain -inferior surface. Scene 2 Expand brainstem. Scene 3, Brain -medial view -midsagittal section. Scene 4 Remove midbrain. Scene 5 Lateral view of brainstem. Rollover mouse to label and click to display page, Click blinking end page to display medulla page.


Cross sections

Lower medulla 1

Lower medulla 2

Lower medulla 3

Upper medulla 1

Upper medulla 2

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