Medulla oblongata

The medulla oblongata (or simply medulla) is the most caudal part of the brainstem and sits between the pons inferiorly and spinal cord superiorly. It is the transition from the spinal cord to the brain.

The medulla contains the vital autonomic cardiovascular and respiratory centers controlling heart rate, blood pressure, and breathing. It is composed of grey matter, cranial nerve (CN) nuclei IX-to-XII, and white matter tracts 2,3.

The medulla is approximately 3 cm in length and 2 cm in greatest diameter 2. The caudal border of the medulla is the 1st cervical spinal nerves. The superior broad part of the medulla joins the pons 2,3.

Medulla is separated into two main parts:

  • ventral (anterior) medulla which contains the olive, pyramidal tracts, and CN 9-12 rootlets
  • tegmentum (dorsal) medulla which contain the CN nuclei and white matter tracts
Ventral medulla

Pyramids are paired structures located at the medial aspect of ventral medulla and flank the anterior median fissure. It contains the anterior and lateral corticospinal tracts. At the caudal end of pyramids the corticospinal tracts decussate 2,3.

Olivary bodies are paired structures located at lateral aspect of ventral medulla, lateral to the pyramids. They are separated from the pyramids by an anterolateral sulcus (pre-olivary sulcus). There is also a post-olivary sulcus lateral to the olivary bodies. Olivary bodies contain the superior and larger inferior olivary nuclei 2.

Medulla tegmentum

The dorsal aspect of the medulla contains the posterior median sulcus (most dorsal medial sulcus) and more lateral posterolateral sulcus. Between these sulci are the fasciculus gracilis and nuclei forming gracilis tubercle at the midline and fasciculus cuneatus and nuclei forming cuneate tubercle more laterally 2,3.

The superior dorsal aspect of medulla forms the floor of the inferior 4th ventricle. It is occupied by the inferior cerebellar peduncle situated between the lower part of the fourth ventricle. The inferior dorsal and lateral aspect of the medulla is surrounded by the cisterna magna (posterior cerebellomedullary cistern), and lateral cerebellomedullary cistern 2,3.

The median aperture (foramen of Magendie) and the more superior lateral apertures (foramina of Luschka) open at the level of the pons, with the canals projecting to the level of the medulla region and terminating into the cisterna magna and lateral cerebellomedullary cistern respectively 1.

Cranial nerves

The nuclei of the cranial nerves in the medulla originate in the tegmentum, but the nerve roots exit ventrally. Cranial nerves IX and X as well as the roots of XI exit the lateral medulla at the post-olivary sulcus, posterior to olivary bodies. Cranial nerve XII emerges between the pyramid and the olive at the pre-olivary sulcus as a number of rootlets 2,3.

The myelencephalon aspect of the rhombencephalon (or hindbrain) becomes the medulla.

Neuroanatomy
Share article

Article Information

rID: 5802
Section: Anatomy
Synonyms or Alternate Spellings:
  • Medulla

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Figure 1: diagram - brainstem
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.