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CROSS SECTIONAL ANATOMY OF THE BRAIN STEM
- 1. CROSS SECTIONAL ANATOMY OF BRAIN STEM PRESENTER – Dr. R.S.K. Karthik, 2nd year M.Ch resident MODERATOR –Dr. M.V. Vijayasekhar , MS M.Ch , Professor and HoD
- 3. Ventral – Lateral View Midbrain Cerebral peduncles Pons Basis pontis Medulla Pyramid Olive Corticospinal tract descends throughout movement Reticular formation descends throughout movement ascends throughout arousal
- 4. Ventral – Dorsal Organization (anterior - posterior) Basis Large anterior fiber tracts: cerebral peduncles, crossing pontine fibers, pyramids
- 5. Ventral – Dorsal Organization Tegmentum Anterior cell body-rich areas, floor of brainstem: red nuclei, substantia nigra, reticular formation
- 6. Ventral – Dorsal Organization Tectum Roof of the brainstem: superior colliculi, inferior colliculi: corpus quadrigemina Cerebellum Cuneatus, gracilis (medulla)
- 7. Ventral – Dorsal Organization Basis Tegmentum Tectum
- 8. Vertical Columns of Cranial Nerves
- 9. 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
- 10. Subdivisions of Vertical Columns • 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)
- 12. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei
- 13. Level of Pyramidal Decussation Pyramidal tract Lateral corticospinal tract 75 – 90% Anterior corticospinal tract -- fibers to innervate muscles of trunk Spinal nucleus of V From pons to C4 Gracile nucleus Contralateral movement
- 14. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei
- 15. Level of Lemniscal Decussation Medial lemniscus Carries 2nd order sensory neurons to VPL thalamus Gracile nucleus Cuneate nucleus Internal arcuate fibers MLF Pyramids Position & vibration sense
- 16. Internal Structure of Medulla Cross section at three levels • Level of pyramidal decussation • Level of lemniscal decussation • Level of inferior olivary nuclei
- 17. Level of Inferior Olives Inferior cerebellar peduncle = Restiform body Inferior olivary nuclei Relay between cortex, vestibular nuclei, cerebellum, basal ganglia, and dorsal column nuclei MLF Vestibular nuclei Medial Inferior Hypoglossal nucleus CN XII Arcuate nuclei pontine nuclei
- 18. Cranial Nerves of the Medulla Vestibular nuclei CN XII
- 19. Cranial Nuclei of the Medulla N. solitarious Sensory nucleus for CN 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
- 21. Cranial Nuclei of the Medulla N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X
- 22. Cranial Nuclei of the Medulla N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X Dorsal motor nucleus of X
- 23. CN IX: Glossopharyngeal Nerve N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X
- 24. CN IX: Glossopharyngeal Nerve N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Posterior 1/3 of the tongue Spinal trigeminal tract CN V, VII, IX, X
- 25. CN IX: Glossopharyngeal Nerve N. ambiguus Motor nucleus for CN IX, X & XI 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
- 26. CN IX: Glossopharyngeal Nerve N. ambiguus Motor nucleus for CN IX, X & XI Stylopharyngeus (lifts pharynx) 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
- 27. CN IX: Glossopharyngeal Nerve N. ambiguus Motor nucleus for CN IX, X & XI Stylopharyngeus (lifts pharynx) 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
- 28. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Spinal trigeminal tract CN V, VII, IX, X “Wanderer”
- 29. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X “Wanderer”
- 30. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X Ear “Wanderer”
- 31. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx N. solitarious Sensory nucleus for CN VII, IX, X Taste, epiglottis Cardiorespiratory Spinal trigeminal tract CN V, VII, IX, X Ear “Wanderer”
- 32. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx 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 “Wanderer”
- 33. CN X: Vagus Nerve N. ambiguus Motor nucleus for CN IX, X & XI Pharynx Larynx 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 “Wanderer”
- 35. Pons Landmarks Basis pontis 4th ventricle Cerebellum and Middle cerebellar peduncle Cranial Nerves V, VI, VII, VIII
- 36. Pontine Nuclei Pontine nuclei Project to cerebellum Continuation of arcuate nuclei (over pyramids) Input (ipsilateral) Motor cortex Sensory cortex Association cortex Cingulate cortex Output (contralateral) Transverse crossing via middle cerebellar peduncle to cerebellum
- 37. 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
- 38. Pons Descending upper motor neurons Connection of pons to cerebellum Restiform body (inf. cerebellar peduncle) Middle cerebellar peduncle Medial lemniscus Ascending 2nd order sensory neurons 4th Ventricle
- 39. Cranial Nerves of Lower Pons CN VIII – Vestibular Nuclei Pure sensory lateral location Balance Posterior view: Cerebullum cut away
- 40. Cranial Nerves of Lower Pons CN VIII – Vestibular Nuclei (Cochlear Nuclei)
- 41. Cranial Nerves of Lower Pons CN VII nucleus – Facial nerve Muscles of face At a slightly higher level CN VI nucleus – Abducens nerve Abduction of eye Longest, most vulnerable CN
- 42. Cranial Nerves of Lower Pons CN VII nucleus - Facial nerve Muscles of face
- 43. Cranial Nerves of Lower Pons CN VI nucleus – Abducens nerve Abduction of eye
- 44. 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
- 45. Mid Pons 4th Ventricle Middle cerebellar peduncle Corticospinal tract, corticobulbar tract, corticopontine fibers Descending fibers
- 46. Mid Pons 4th Ventricle Middle cerebellar peduncle Pontine nuclei in basis
- 47. Mid Pons Pontine nuclei Trapezoid body – transverse fibers in pontine tegmentum from cochlear nucleus hearing Lateral lemniscus
- 48. Mid Pons Pontine nuclei Lateral lemniscus Medial lemniscus fibers from dorsal column (position and vibration) Trigeminal tract pain, temperature, touch from contralateral face Lemniscal sensory system – in tegmentum of the pons
- 49. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus
- 50. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus Principal trigeminal sensory nucleus
- 51. Cranial Nerve of the Mid Pons 4th Ventricle CN V Motor trigeminal nucleus Principal trigeminal sensory nucleus Trigeminal fascicles Trigeminal nerve
- 52. 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
- 53. Upper Pons 4th ventricle cerebral aqueduct Superior cerebellar peduncle decussation
- 54. Upper Pons 4th ventricle cerebral aqueduc Superior cerebellar peduncle Descending upper motor neurons Transverse ponto-cerebellar fibers
- 55. Upper Pons 4th ventricle cerebral aqueduc MLF Periaqueductal gray matter
- 56. Upper Pons 4th ventricle cerebral aqueduc MLF Locus ceruleus Primary source of noradrenergic innervation to the brain Neurons contain melanin
- 57. Upper Pons 4th ventricle cerebral aqueduc MLF Parabrachial Nucleus Also release catecholamines Neurons also contain melanin
- 58. Upper Pons 4th ventricle cerebral aqueduc MLF Pediculopontine Nucleus Some neurons release acetylcholine Other neurons release glutamate They assist in learning and voluntary motor control, e.g. locomotion, saccadic eye
- 60. Midbrain Landmarks Cerebral peduncles Optic chiasm Interpeduncular fossa (Superior colliculi) (Inferior colliculi) (Superior cerebellar peduncle) Cranial Nerves III, IV
- 61. Patterning of the Midbrain
- 62. External Structure of Midbrain 1. Optic chiasm 2. Interpeduncular fossa 3. Oculomotor nerve (CN III) 4. Trochlear nerve (CN IV) 5. Pons 6. Cerebral peduncles (crus cerebri) Ventral surface (anterior)
- 63. External Structure of Midbrain Quadrigeminal Plate • Superior colliculus • Inferior colliculus Dorsal surface Cerebellum removed CN IV Trochlear nerve
- 64. Cranial Nerves of the Midbrain Anterior exit CN III (1) CN VI (5) Posterior exit CN IV (2) MLF - Medial longitudinal fasciculus (7) Vestibular nuclei (6) Pons (3)
- 65. Internal Structure of Midbrain Cross section at two levels • Level of inferior colliculus • Level of superior colliculus
- 66. Lower Midbrain Inferior colliculus hearing cerebral aqueduct DORSAL VENTRAL cerebral peduncles
- 67. Lower Midbrain Inferior colliculus Substantia nigra Melanin-containing cells that produce dopamine Project to the basal ganglia
- 69. Lower Midbrain Inferior colliculus CN IV Trochlear nerve
- 70. Lower Midbrain Inferior colliculus CN IV Trochlear nerve MLF
- 71. Lower Midbrain Inferior colliculus CN IV MLF Dorsal raphe nucleus – projects serotonergic fibers to basal ganglia and throughout cortex
- 72. Lower Midbrain Inferior colliculus hearing Mesencephalic nucleus of V analogous to dorsal root ganglion but within CNS
- 73. Internal Structure of Midbrain Cross section at two levels • Level of inferior colliculus • Level of superior colliculus
- 74. Upper Midbrain Superior colliculus vision Substantia nigra Crus cerebri (cerebral
- 75. Upper Midbrain Superior colliculus vision Medial geniculate body hearing
- 76. Upper Midbrain Vision Superior colliculus Lateral geniculate body Hearing Inferior colliculus Medial geniculate body
- 77. Upper Midbrain Superior colliculus vision Red nucleus – relay from cortex and cerebellum to spinal cord, inferior olive, reticular formation, cerebellum Controls arm movement
- 78. Cranial Nerves of Upper Midbrain Superior colliculus vision Red nucleus CN III Oculomotor nucleus Edinger Westfal nucleus Parasympathetic to ciliary ganglion Pupillary sphincter ciliary muscles
- 79. Cranial Nerves of Upper Midbrain Superior colliculus vision Red nucleus Edinger Westfal nucleus MLF CN III Oculomotor nucleus
- 80. Innervation of Eye Muscles Dorsal view Cerebellum removed
- 81. Innervation of Eyes & Muscles Lacrimal gland (CN VII) Superior rectus Inferior rectus Medial rectus Inferior Oblique (CN III) Superior oblique (CN IV) Lateral rectus (CN VI) Parasympathetic: Edinger-Westfal (CN III) Sympathetic: Superior Cervical Ganglion
- 82. THANK YOU