This document discusses the medulla oblongata and includes three case studies. It provides information on ascending and descending tracts in the medulla, cranial nerve nuclei located in the medulla, and discusses the cases of a patient with tongue deviation and difficulty swallowing, and another with dizziness. The likely lesion for the second case is an ischemic stroke of the left paramedian branches of the anterior spinal artery affecting cranial nerve XII. For the third case, a possible explanation is an ischemic stroke of the posterior inferior cerebellar artery affecting the vestibular nuclei.

1. MEDULLA
MICHAEL STAR, MD
Department of Neurology
Loyola University Medical Center
June 2012
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2. CASE 1
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3. BASICS
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5. CROSSROADS
OF…YOUR BRAIN
Ascending Tracts:
1) Dorsal column tract (fine touch, vibration, proprioception)  gracile
and cuneate nuclei  lemniscal decussation  medial lemniscus 
thalamus
2) Spinothalamic (pain, temp.)  Thalamus
-Decussation at/above spinal level, not medulla!
Descending Tracts:
1) Corticospinal tract  medullary pyramid  pyramidal decussation 
Lateral and anterior corticospinal tract
2) Medial longitudinal fasciculus (gaze/head movement)  Vestibular
nuclei (pons/medulla)  spinal cord
-Also ascends to CN III, IV, and VI
3) Descending tract of CN V (pain, temperature, crude touch)  Cell
bodies in in trigeminal ganglion  spinal nucleus of CN V
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7. CRANIAL NERVE NUCLEI
IN THE MEDULLA
• Hypoglossal nucleus (XII), dorsal motor nucleus of vagus (X),
and solitary tract and nucleus (sensory for VII, IX, and X) are
found below the 4th ventricle
• Hypoglossal nucleus sends its fibers ventrally between the
pyramid and inferior olivary nucleus
• Ambiguus nucleus has motor fibers which exit laterally to
nerves IX and X to control swallowing and vocalization
• Dorsal motor nucleus of X sends its fibers laterally (along
with the ambiguus nucleus fibers) to control parasympathetic
tone in heart, lungs, and abdominal viscera
• Solitary nucleus that receives axons from VII, IX, and X
conveys information about taste via the VPM nucleus in the
the thalamus which projects to cortex (area 43)
• 4 Vestibular nuclei (superior, inferior, medial, and lateral) are
found partially in the medulla, partially in the pons
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14. CASE 1 REVISITED
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17. CASE 1 DISCUSSED
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18. CASE 2
A 62 year old man with history of smoking, obesity, diabetes
mellitus type 2, hypertension, and hyperlipidemia presents
because for the past 2 days he has been having problems
talking and swallowing. He feels that he has developed
something of a lisp and that when he eats, he feels like the
food is not moving to the back of his mouth. His wife thinks
he is crazy. Patient denies any other symptoms.
On physical exam, you note tongue deviation to the right
side.
What is the diagnosis? Where is the lesion?
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19. HINT
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20. CASE 2 DISCUSSED
The patient’s tongue deviates to the right because of
weakness of the left tongue. While multiple locations could
possibly explain this lesion, the sudden onset of symptoms
is likely an ischemic stroke of the left paramedian branches
of the anterior spinal artery affecting the fibers of the left
cranial nerve 12, which causes ipsilateral hemiparalysis of
the tongue
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21. CASE 3
A 32 year old woman with Factor V Leiden and on OCPs
presents to the ED with complaints of dizziness and falls for the
last 4 days. The patient note the room “feels like it’s spinning
around me.” The patient first presented to Loretto two days
prior, where, because they don’t have an MRI, they told her she
had BPPV and demonstrated how to do the Epley maneuver and
discharged her. She presents now because she says it has not
helped. Patient notes that dizziness does not resolve with
sitting, standing, or laying supine, and Dix-Hallpike, while
annoying, did not make her more or less dizzy. You perform an
MRI, but the patient gets nauseous midway through the MRI and
starts moving. You note no lesions in the cerebellum or
supratentorially, however, the brain stem isn’t visualized due to
motion artifacts. ENT performs vestibular testing which rules
out peripheral vertigo.
Where could the lesion be?
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22. HINT
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23. CASE 3
One possible explanation for the patient’s symptoms along
with an otherwise negative MRI and vestibular testing is an
ischemic stroke of the posterior inferior cerebellar artery
(PICA) affecting the Vestibular nuclei.
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