Brainstem

1. Brain StemBrain Stem
SMS 1084SMS 1084
Dr. Mohanad R. AlwanDr. Mohanad R. Alwan

2. Major Brain Stem ActivitiesMajor Brain Stem Activities
 ConduitConduit
 Ascending and descending pathwaysAscending and descending pathways
 Integrative functionsIntegrative functions
 Complex motor patternsComplex motor patterns
 Respiratory and cardiovascular activityRespiratory and cardiovascular activity
 Regulation of arousal and level ofRegulation of arousal and level of
consciousnessconsciousness
 Cranial Nerve functionsCranial Nerve functions

3. Major ExternalMajor External
FeaturesFeatures

4. Brain StemBrain Stem
Midbrain
Pons
Medulla

5. MidbrainMidbrain
 Cerebral PedunclesCerebral Peduncles
 Interpeduncular cisternInterpeduncular cistern
 Origin of CN III -- Oculomotor NerveOrigin of CN III -- Oculomotor Nerve
 Corpora QuadrigeminaCorpora Quadrigemina
 Superior ColliculiSuperior Colliculi
 Inferior ColliculiInferior Colliculi

6. MidbrainMidbrain
 Substantia nigraSubstantia nigra
 Red nucleusRed nucleus

7. MidbrainMidbrain
Corpora
quadrigemina
Cerebral
peduncles
Interpeduncular
cistern
CN III

8. PonsPons
 Cerebellar PedunclesCerebellar Peduncles
 Superior (Dives under the colliculi)Superior (Dives under the colliculi)
 Middle (Bridge of the pons)Middle (Bridge of the pons)
 Inferior (inferior/medial to middle)Inferior (inferior/medial to middle)
 Floor of the 4th VentricleFloor of the 4th Ventricle

9. PonsPons
 4th ventricle4th ventricle
 Pontine nucleiPontine nuclei
 Locus ceruleusLocus ceruleus

10. PonsPons

11. PonsPons
Middle cerebellar peduncle

12. PonsPons
Middle cerebellar peduncle
Inferior cerebellar peduncles
Superior cerebellar peduncles

13. PonsPons
 4th Ventricle4th Ventricle
 Inflow from aqueduct ofInflow from aqueduct of
SylviusSylvius
 Sulcus limitansSulcus limitans

14. MedullaMedulla
 PyramidsPyramids
 Pyramidal decussationPyramidal decussation
 Inferior oliveInferior olive
 Obex (inferiormost point of the 4thObex (inferiormost point of the 4th
ventricle)ventricle)

15. MedullaMedulla
Pyramids
Obex
Inferior olive

16. MedullaMedulla
Inferior Olive
Pyramids

17. Caudal MedullaCaudal Medulla
 Sensory nucleiSensory nuclei
 Nucleus GracilisNucleus Gracilis
 Nuclues CuneatusNuclues Cuneatus
 Pyramidal decussationPyramidal decussation

18. Tectum and TegmentumTectum and Tegmentum
 TectumTectum
 Area posterior to the ventricular spaceArea posterior to the ventricular space
 Only prominent in the midbrainOnly prominent in the midbrain
 Superior and inferior colliculi (“tectal plate”)Superior and inferior colliculi (“tectal plate”)

19. Tectum and TegmentumTectum and Tegmentum
Tectal Plate

20. Tectum and TegmentumTectum and Tegmentum
 TegmentumTegmentum
 Area anterior to the ventricular space (but notArea anterior to the ventricular space (but not
everything anterior)everything anterior)
 This is the embryologically oldest areas of theThis is the embryologically oldest areas of the
brainstembrainstem

21. Big Four PathwaysBig Four Pathways

22. Remember the Big Four?Remember the Big Four?
Corticospinal tract
Dorsal Columns
Spinothalamic tract
Spinocerebellar tracts

23. Big Four PathwaysBig Four Pathways
 Corticospinal tractCorticospinal tract
 Descending motorDescending motor
 Spinothalamic tractSpinothalamic tract
 Ascending pain/temperatureAscending pain/temperature
 Dorsal columns/Medial lemniscusDorsal columns/Medial lemniscus
 Ascending somatosensory and consciousAscending somatosensory and conscious
proprioceptionproprioception
 Spinocerebellar tractsSpinocerebellar tracts
 Ascending unconscious proprioceptionAscending unconscious proprioception

24. The Big Four -- Caudal MedullaThe Big Four -- Caudal Medulla
Corticospinal tract
Medial Lemniscus
Spinothalamic tract
Spinocerebellar tracts
Lateral Cuneate Nucleus

25. The Big Four…err…three -- PonsThe Big Four…err…three -- Pons
Corticospinal tract
Medial Lemniscus
Spinothalamic tract

26. The Big Three -- MidbrainThe Big Three -- Midbrain
Corticospinal tract
Medial Lemniscus
Spinothalamic tract

27. Brain Stem NucleiBrain Stem Nuclei

28. Brain Stem NucleiBrain Stem Nuclei
 Major neurotransmitter nucleiMajor neurotransmitter nuclei
 Reticular formation (not really a “nucleus”Reticular formation (not really a “nucleus”
but acts like a group of nuclei)but acts like a group of nuclei)
 Nuclei associated with cranial nervesNuclei associated with cranial nerves

29. Raphe NucleiRaphe Nuclei
 Ridge of cells along the midline in theRidge of cells along the midline in the
center of the brainstemcenter of the brainstem
 Multiple nucleiMultiple nuclei
 CaudalCaudal
 projections to the spinal cord and other partsprojections to the spinal cord and other parts
of the brainstemof the brainstem
 RostralRostral
 projections to multiple cortical areasprojections to multiple cortical areas

30. Raphe NucleiRaphe Nuclei
 Major serotonin nucleiMajor serotonin nuclei
 Technically part of theTechnically part of the reticular formationreticular formation
 Complex reciprocal relationships with multipleComplex reciprocal relationships with multiple
areasareas
 Ascending pathways involved in manyAscending pathways involved in many
neurobehavioral phenomenaneurobehavioral phenomena
 MoodMood
 SleepSleep
 Feeding/satietyFeeding/satiety
 Descending pathways modulate spinal cordDescending pathways modulate spinal cord
functionfunction
 PainPain

31. Locus CeruleusLocus Ceruleus
 Major norepinephrine nucleusMajor norepinephrine nucleus
 Dorsal wall of the rostral ponsDorsal wall of the rostral pons
 Projects toProjects to
 Spinal cordSpinal cord
 Brain StemBrain Stem
 CortexCortex

32. Locus CeruleusLocus Ceruleus
 FunctionFunction
 ArousalArousal
 Modulation of stress responsesModulation of stress responses
 Linked toLinked to
 DepressionDepression
 AnxietyAnxiety
 Post-traumatic stress disorderPost-traumatic stress disorder
 Accounts for some of the psychiatricAccounts for some of the psychiatric
symptoms in Parkinson’s Diseasesymptoms in Parkinson’s Disease

33. Locus CeruleusLocus Ceruleus
Normal Parkinson’s Disease

34. Substantia NigraSubstantia Nigra
 One of a few major dopamine centerOne of a few major dopamine center
 Projects to the basal gangilaProjects to the basal gangila
 FunctionFunction
 Modulation of movementsModulation of movements
 Major role in Parkinson’s DiseaseMajor role in Parkinson’s Disease
 NOT involved in psychiatric symptomsNOT involved in psychiatric symptoms

35. Nucleus Basalis of MeynertNucleus Basalis of Meynert
 NOT in the brainstem, but importantNOT in the brainstem, but important
 Located in the basal forebrainLocated in the basal forebrain
 Major acetylcholine nucleus in the brainMajor acetylcholine nucleus in the brain
 Provides tonic stimulation to theProvides tonic stimulation to the
hippocampushippocampus

36. Nucleus Basalis of MeynertNucleus Basalis of Meynert
 Major neurotransmitter associated withMajor neurotransmitter associated with
Alzheimer’s DiseaseAlzheimer’s Disease
 Major medications for Alzheimer’s areMajor medications for Alzheimer’s are
cholinesterase inhibitorscholinesterase inhibitors

37. Coming Up…Coming Up…
 Spinal cordSpinal cord