Anatomy Bones and Muscles · MU Pleven

127. Medulla

Explains the medulla oblongata as the most inferior part of the brainstem, joined above to the pons and continuing below into the spinal cord, and notes its length. Lists the external surface features such as the pyramids, decussation, inferior olives, grooves with the cranial nerves that exit there, and the cerebellar peduncle. Covers the internal structure at two levels, followed by cross-sectional lists of cranial nerve nuclei, brainstem nuclei, and ascending and descending tracts.

Inside: 4 sections · 9 labelled pictures · 10 flashcards · 5 min

Topic 126 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 4 sections, about 689 words (5 min of reading), with 10 flashcards.

In this note

  1. MEDULLA OBLONGATA
  2. External medulla oblongata:
  3. Internal Surface
  4. Cross Sections :

MEDULLA OBLONGATA

Brainstem : is a stalklike structure within the posterior cranial fossa, consists of the midbrain, pons & medulla oblongata.

Medulla oblongata :

  • The most inferior /caudal part of the brainstem
  • Superiorly its connected to the pons, and inferiorly it becomes the spinal cord at the foramen magnum.
  • Is the longest portion of the brainstem (~3cm)

External medulla oblongata:

  1. 1 Pyramid (pyramis medullae oblongatae)
  • – a paired elevation of the medulla oblongata containing the corticospinal tract
  1. 1.1 Decussation of pyramids / motor decussation (decussatio pyramidum) – the site where the fibres of the corticospinal tract cross to the opposite side
  2. 2 Ventral median fissure (fissura mediana anterior)
  3. 3 Inferior olive (oliva) – a paired elevation on the ventral surface of the medulla oblongata formed by the the inferior olivary complex
  4. 3.1 Pre-olivary groove (sulcus preolivaris) – a groove in front of the inferior olive, the exit of the n. XII
  5. 3.2 Retro-olivary groove (sulcus retroolivaris) – a groove behind the inferior olive, the exit of the n. IX, X and XI
  1. 4 Medullopontine sulcus (sulcus bulbopontinus) – a transverse groove between the medulla oblongata and pons – the exit of the n. VI
  2. 5 Inferior cerebellar peduncle (pedunculus cerebellaris inferior)
  • – consists of the restiform and juxtarestiform body
  • – connects the medulla oblongata to the cerebellum
  • – contains the afferent and efferent tracts of the cerebellum
  1. 6 Rhomboid fossa (fossa rhomboidea) – together with the pons forms the rhomboid-shaped floor of the fourth ventricle
  2. 7 Gracile tubercle (tuberculum gracile) – the medial tubercle on the dorsal surface is formed by the gracile nucleus
  3. 8 Cuneate tubercle (tuberculum cuneatum) – the lateral tubercle on the dorsal surface is formed by the cuneate nucleus
  4. 9 Trigeminal tubercle (tuberculum trigeminale)
  • – a tubercle on the lateral surface is formed by the spinal nucleus and tract of trigeminal nerve

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