1 / 55

Brainstem & Diencephalon

Brainstem & Diencephalon. Lecture Objectives. Identify the gross features of the brainstem .

ursulaa
Download Presentation

Brainstem & Diencephalon

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Brainstem &Diencephalon

  2. LectureObjectives • Identify the gross features of the brainstem. • Briefly describe the internal structure of the brainstem (ascending and descending pathways, sensory and motor cranial nuclei, substantia nigra, red nucleus, olivary nucleus and reticular formation). • Describe the main connections of the sensory cranialnuclei. • Describe the main connections of the motor cranialnuclei. • Review the blood supply of thebrainstem. • Describe lesions in the brainstem such as medial medullary syndrome and lateral medullary syndrome. • Describe the main connections of the substantia nigra and the red nucleus. • Describe the main connections of Reticular Formation and correlate these connections with its mainfunctions. • Describe the anatomical features of the diencephalon; components, location andrelations.

  3. Principal Parts of theBrain • Cerebrum • Diencephalon • Thalamus, hypothalamus& epithalamus • Cerebellum • Brainstem • medulla, pons& midbrain

  4. BrainstemFunctions • Ascending and descendingtracts • Reflexcenters • Cardiovascular and respiratorycenters • Coughing, sneezing,swallowing • Nuclei of the cranialnerves • Motor and sensory • Consciousness andarousal

  5. External Anatomy ofBrainstem: Ventrally • Midbrain • Cerebral peduncles (basis pedunculi) • Interpeduncularfossa • Pons • Basilarpons • Basilarsulcus • Bulbopontinesulcus • Medullaoblongata

  6. External Anatomy ofBrainstem: Ventrally • Bulbopontinesulcus • Medullaoblongata • Ventral median fissure • Pyramids • Decussation ofpyramids • Olives • Pre‐olivary &post‐ olivary sulci • Inferiorcerebellar peduncles

  7. External Anatomy ofBrainstem: Dorsally • Corpora quadrigemini (midbrain) • Superior & inferiorcolliculi • Cerebellarpeduncles • Lateral walls of 4thventricle • Gracile & cuneate tubercles (closed surface of medulla) • Inferior to 4thventricle • Rhomboid fossa • Pontine part • Medullary part(open medulla)

  8. RhomboidFossa • Posterior mediansulcus • Medial eminence(pons) • Facialcolliculus • Caudal part of theeminence • Sulcus limitans • Striaemedullares • Trigons • Vagal trigon (morelateral‐inferior) • Hypoglossal trigon (moremedial‐ superior) • Vestibularareas • Lateral points of thefossa • Isthmus – superiorconstriction • Obex – inferiornarrowing

  9. Midbrain Medulla Pons BrainstemStructure

  10. Functional Distribution of BrainstemNuclei • Midline • GSE – III, IV, VI, XII • SVE – V, VII, IX, X,XI • GVE – III, VII, IX,X • Sulcuslimitans • GVA – n. of tractus solitarius • SVA – n. of tractussolitarius • GSA – V sensorynuclei • SSA – vestibular &cochlear

  11. BrainstemNuclei

  12. BrainstemNuclei

  13. Internal Structures ofMedulla • Level of pyramidal decussation (closed part) • Cranial nervenuclei • Spinal tract & nucleusof trigeminal nerve • Motorpathways • Pyramids • – Decussation ofpyramids • Somatosensorypathways • Nucleus gracilis &cuneatus • Fasciculus gracilis& cuneatus

  14. Internal Structures ofMedulla • Level of internal arcuate fibers (closedpart) • Cranial nervenuclei • Spinal tract & nucleusof trigeminal nerve • Motorpathways • Pyramids • Somatosensorypathways • Fasciculus gracilis& cuneatus • Nucleus gracilis &cuneatus • Internal arcuatefibers • –Decussation

  15. Internal Structures ofMedulla • Level of olivary nucleus (openpart) • Cranial nervenuclei • Hypoglossalnucleus • Dorsal vagalnucleus • Vestibular nuclei • Nucleus of tractussolitarius • Spinal tract & nucleus of trigeminal nerve • Motor pathways • Pyramid • Olivarynucleus • Inferior cerebellarpeduncle • Somatosensorypathways • Mediallemniscus

  16. Internal Structures of thePons • Caudalpart • Cranial nervenuclei • Nucleus ofabducent nerve • Motor nucleus of facial nerve • Motorpathways • Somatosensory pathways • Mediallemniscus

  17. Internal Structures of thePons • Cranialpart • Cranial nervenuclei • Motor nucleusof trigeminalnerve • Main sensory nucleusof trigeminal • Motorpathways • Middle & superior cerebellarpeduncles • Pontinenuclei • Corticospinalfibers • Somatosensorypathways • Mediallemniscus

  18. Internal Structures of theMidbrain • Level of inferior colliculi • Cranial nervenuclei • Nucleus of trochlearnerve • Mesencephalic nucleusof trigeminal nerve • Motorpathways • Inferiorcolliculi • Decussation ofsuperior cerebellarpeduncles • Substantianigra • Cruscerebri • Somatosensorypathways • Medial lemniscus

  19. Internal Structures of theMidbrain • Level of the superior colliculi • Cranial nervenuclei • Nucleus ofoculomotor nerve • Motorpathways • Superiorcolliculi • Rednucleus • Substantianigra • Cruscerebri • Somatosensorypathways • Mediallemniscus

  20. Spinal cord & Brainstem Labeled Sections: ExternalLink • http://www.bellarmine.edu/faculty/mwiegand/atlas/ cover.html

  21. Blood Supply toBrainstem • Blood supply to BS is from posteriorcirculation • Vertebrala. • Anterior spinala. • PICA • Basillara. • AICA • Paramedianbranches • Circumferentialbranches • Short &long • SCA • PCA

  22. Blood Supply toBrainstem

  23. Blood Supply:Medulla • Anterior spinala. • Vertebrala. • PICA

  24. MedullaryLesions Lateral medullary(Wallenberg) Medial medullarysyndrome syndrome

  25. Blood Supply:Pons • Caudalpons • Basilara. • Paramedian • Circumferential • AICA • Rostralpons • Basilara. • Paramedian • Circumferential • SCA

  26. Blood Supply:Midbrain • Paramedian branches (Basilara.) • PCA • –Quadrigeminal • SCA

  27. Midbrain Lesions Weber’ssyndrome Benedikt’ssyndrome

  28. ReticularFormation • Scattered nuclei in medulla, pons &midbrain • Lateral one third have small cells (parvocellular) • Receive sensory inputs and corticalinputs • Medial two thirds have large cells (magnocellular) • Output to spinal cord, brainstem nuclei, thalamus, hypothalamus & cerebral cortex

  29. Reticular FormationFunctions • The reticular formation modulates (excite or inhibit) the activitiesof: • Sensory systems – e.g.pain • Motor systems – e.g. muscle tone, segmental reflexes, eyemovements • Autonomic systems – e.g. respiration, blood pressure, cardiacfunction • Consciousness – e.g. vital centers in the brainstem, awareness, attention &arousal

  30. Organization of ReticularFormation • Reticular formation organized into three longitudinalcolumns • Midline raphe group • Parasagittal medial zone • Parasagittal lateralzone

  31. Organization of ReticularFormation • Fourth set of nuclei that have common cerebellar projections (precerebellar reticular nuclei) • Coordination ofmuscle contraction • Paramidian reticular nucleus of themedulla • Lateral reticular nucleus of the medulla • Reticulotegmental nucleusof thepons

  32. RapheNuclei • Serotonin projectingcells • Rostral group (upper pons & midbrain) • Project to cerebellum, cerebrum (cortex, basal ganglia, limbicsystem) • Involved in the regulation of forebrainactivity • Sleep, memory processing,mood • Caudal group (lower pons & medulla) • Receives nociceptive input from brainstem & spinalcord • Involved in the regulation ofpain

  33. Medial Reticular Zone • The effector part of the reticularformation • Provides most of the ascending & descendingprojection • Most inputs come from the lateral reticular zone (sensory somatic & visceral) • Ascending projections form the Ascending Reticular Activating System(ARAS) • Alter the levels of consciousness & state ofattention • Conscious activities of the cerebral cortex require excitatory influences from the ARAS • Descending projections regulate muscle tone, spinal reflexes & motor activity through • Medial (pontine) reticulospinaltract • ↑ muscle tone spinalreflexes • Lateral (medullary) reticulospinaltract • ↓ muscle tone spinalreflexes

  34. Medial Reticular Zone • Locus ceruleus inpons • contain norepinephrine & extensive projections throughoutCNS • Ascending projections are part of theARAS • Involved in the mood, memory and regulation of motoractivity

  35. Lateral ReticularZone • Receives extensive afferents to mediate cranial nerve reflexes and visceralfunctions • Output is mainly to medialzone • Otherprojections • Pedunculopontine nucleus (acetylcholineneurons) • Projects to the substantia nigra, subthalamic nucleus, motor cortex, & medialzone • – All have important motor controlfunctions

  36. Organization of Reticular Formation NeurotransmitterDistribution

  37. Reticular Formation: Neurotransmitter Pathways &Functions

  38. TheDiencephalon

  39. Thalamus:Structure • From medial tolateral: • Medialn. • Dorsomedialn. • Anterior n. • Internal medullarylamina • Intralaminarn. • – Lateraln. • External medullarylamina • – Reticular n. • Internalcapsule

  40. Thalamus: LateralNucleus • Subdividedinto: • Dorsal tier • Lateral dorsal(LD) • Lateral posterior(LP) • Pulvinar (Pu) • Ventraltier • Ventral anterior(VA) • Ventral lateral(VL) • Ventral posterior(VP) • Ventral posterolateral(VPL) • Ventral posteromedial(VPM) • Posterior nucleus (Po) • Medial & lateral geniculate nuclei

  41. SpecificNuclei

  42. Non‐specificNuclei

  43. Hypothalamus • Location • Boundaries • Laminaterminalis • Hypothalamicsulcus • 3rdventricle

  44. Hypothalamus:Nuclei • Divisions • In coronalsection • Periventricular • Medial • Fornix • Lateral

  45. Hypothalamus:Nuclei • Divisions • In sagittalsection • Chiasmatic (anterior, supraoptic) • Tuberal(middle) • Mamillary(posterior)

More Related