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Brainstem

Brainstem. Overview Medulla Pons Midbrain. January 12, 2009. Ventral – Lateral View. Corticospinal tract descends throughout  movement Reticular formation descends throughout  movement ascends throughout  arousal. Midbrain Cerebral peduncles. Pons Basis pontis. Medulla

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Brainstem

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  1. Brainstem Overview Medulla Pons Midbrain January 12, 2009

  2. Ventral – Lateral View Corticospinal tract descends throughout  movement Reticular formation descends throughout  movement ascends throughout  arousal Midbrain Cerebral peduncles Pons Basis pontis Medulla Pyramid Olive

  3. Ventral – Dorsal Organization(anterior - posterior) Basis Large anterior fiber tracts: cerebral peduncles, crossing pontine fibers, pyramids

  4. Ventral – Dorsal Organization Tegmentum Anterior cell body-rich areas, floor of brainstem: red nuclei, substantia nigra, reticular formation

  5. Ventral – Dorsal Organization Tectum Roof of the brainstem: superior colliculi, inferior colliculi: corpus quadrigemina Cerebellum Cuneatus, gracilis (medulla)

  6. Ventral – Dorsal Organization Tectum Tegmentum Basis

  7. Vertical Columns of Cranial Nerves

  8. Internal Columns of Nuclei III, IV, VI, XII V, VII, N. ambiguus, XII EW, Salivatory, DMN X V, VII, IX, X N. Solitary tract VIII

  9. Motor nuclei Somatic motor closest to midline eyes, tongue CN III, IV, VI, XII Branchial motor Lateral position Branchial arches: chewing, expression, middle ear, pharynx, larynx, sternomastoic, trapezius CN V, VII, XI N. ambiguus (IX, X) Visceral motor ventral / ventrolateral Parasympathetic: glands, smooth muscle, heart, lungs, GI above splenic flexure Edinger-Westfall (III) Sup. & Inf. salivatory (VII) Dorsal motor nucleus of X Sensory nuclei General sensory lateral to branchial motor Face, sinuses, meninges All modalities CN V mainly Also CN VII, IX, X Visceral sensory lateral to visceral motor Taste; cardiorespiratory, GI info N. of the solitary tract (CN VII, IX, X) Special sensory furthest lateral Balance; hearing CN VIII (vestibular) CN VIII (cochlear) Subdivisions of Vertical Columns

  10. Brainstem Overview Medulla Pons Midbrain .

  11. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei

  12. Level of Pyramidal Decussation Lateral corticospinal tract 75 – 90% Gracile nucleus Spinal nucleus of V From pons to C4 Contralateral movement Pyramidal tract Anterior corticospinal tract -- fibers to innervate muscles of trunk

  13. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei

  14. Level of Lemniscal Decussation Gracile nucleus Cuneate nucleus MLF Position & vibration sense Pyramids Medial lemniscus Carries 2nd order sensory neurons to VPL thalamus Internal arcuate fibers

  15. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei

  16. Level of Inferior Olives Vestibular nuclei Medial Inferior Hypoglossal nucleus CN XII Inferior cerebellar peduncle = Restiform body Inferior olivary nuclei MLF Relay between cortex, vestibular nuclei, cerebellum, basal ganglia, and dorsal column nuclei Arcuate nuclei  pontine nuclei

  17. Cranial Nerves of the Medulla Vestibular nuclei CN XII

  18. Cranial Nuclei of the Medulla N. solitarious Sensory nucleus for CN VII, IX, X

  19. Cranial Nuclei of the Medulla N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X

  20. Cranial Nuclei of the Medulla N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  21. Cranial Nuclei of the Medulla N. solitarious Sensory nucleus for CN VII, IX, X Dorsal motor nucleus of X Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  22. CN IX: Glossopharyngeal Nerve N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  23. CN IX: Glossopharyngeal Nerve N. solitarious Sensory nucleus for CN VII, IX, X Posterior 1/3 of the tongue Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  24. CN IX: Glossopharyngeal Nerve N. solitarious Sensory nucleus for CN VII, IX, X Posterior 1/3 of the tongue Spinal trigeminal tract CN V, VII, IX, X Sensation behind ear N. ambiguus Motor nucleus for CN IX, X & XI

  25. CN IX: Glossopharyngeal Nerve N. solitarious Sensory nucleus for CN VII, IX, X Posterior 1/3 of the tongue Spinal trigeminal tract CN V, VII, IX, X Sensation behind ear N. ambiguus Motor nucleus for CN IX, X & XI Stylopharyngeus (lifts pharynx)

  26. CN IX: Glossopharyngeal Nerve N. solitarious Sensory nucleus for CN VII, IX, X Posterior 1/3 of the tongue Inf. salivatory nucleus Parotid gland, parasympathetic Spinal trigeminal tract CN V, VII, IX, X Sensation behind ear N. ambiguus Motor nucleus for CN IX, X & XI Stylopharyngeus (lifts pharynx)

  27. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  28. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X N. ambiguus Motor nucleus for CN IX, X & XI

  29. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X Ear N. ambiguus Motor nucleus for CN IX, X & XI

  30. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X Ear N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx

  31. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Dorsal motor nucleus of X Spinal trigeminal tract CN V, VII, IX, X Ear N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx

  32. CN X: Vagus Nerve “Wanderer” N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Dorsal motor nucleus of X Parasympathetic, preganglionic Spinal trigeminal tract CN V, VII, IX, X Ear N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx

  33. Brainstem Overview Medulla Pons Midbrain

  34. Pons Landmarks Basis pontis 4th ventricle Cerebellum and Middle cerebellar peduncle Cranial Nerves V, VI, VII, VIII

  35. Pontine Nuclei Input (ipsilateral) Motor cortex Sensory cortex Association cortex Cingulate cortex Output (contralateral) Transverse crossing via middle cerebellar peduncle to cerebellum Pontine nuclei Project to cerebellum Continuation of arcuate nuclei (over pyramids)

  36. Internal Structure of the Pons • Cross section at three levels • Level of facial nucleus (CN VII) • Level of middle cerebellar peduncle • Level of locus ceruleus

  37. Pons 4th Ventricle Connection of pons to cerebellum Restiform body (inf. cerebellar peduncle) Middle cerebellar peduncle Medial lemniscus Ascending 2nd order sensory neurons Descending upper motor neurons

  38. Cranial Nerves of Lower Pons Posterior view: Cerebullum cut away CN VIII – Vestibular Nuclei Pure sensory  lateral location Balance

  39. Cranial Nerves of Lower Pons CN VIII – Vestibular Nuclei (Cochlear Nuclei)

  40. Cranial Nerves of Lower Pons At a slightly higher level CN VI nucleus – Abducens nerve Abduction of eye Longest, most vulnerable CN CN VII nucleus – Facial nerve Muscles of face

  41. Cranial Nerves of Lower Pons CN VII nucleus - Facial nerve Muscles of face

  42. Cranial Nerves of Lower Pons CN VI nucleus – Abducens nerve Abduction of eye

  43. Internal Structure of the Pons • Cross section at three levels • Level of facial nucleus (CN VII) • Level of middle cerebellar peduncle • Level of locus ceruleus Anterior view

  44. Mid Pons 4th Ventricle Middle cerebellar peduncle Corticospinal tract, corticobulbar tract, corticopontine fibers Descending fibers

  45. Mid Pons 4th Ventricle Middle cerebellar peduncle Pontine nuclei in basis

  46. Mid Pons Lateral lemniscus from cochlear nucleus hearing Pontine nuclei Trapezoid body –transverse fibers in pontine tegmentum

  47. Mid Pons Medial lemniscus fibers from dorsal column (position and vibration) Lateral lemniscus Trigeminal tract pain, temperature, touch from contralateral face Pontine nuclei Lemniscal sensory system – in tegmentum of the pons

  48. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus

  49. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus Principal trigeminal sensory nucleus

  50. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus Trigeminal fascicles Trigeminal nerve Principal trigeminal sensory nucleus

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