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Pons Anatomy

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Published on

Dr. Mehul Tandel
Assistant Professor
Anatomy Department
Pramukhswami Medical College
Karamsad, Gujarat

Published in: Health & Medicine

Pons Anatomy

  1. 1. PONS D r . M e h u l T a n d e l
  2. 2. Objectives: (1) External features of Pons (2) Internal features of Pons– cross sections (1) At the level of Facial Colliculus (2) At the level of Motor & Sensory Nucleus of trigeminal nerve (3) Blood supply with Applied aspects
  3. 3. Connects the medulla & midbrain Function Transmit information between spinal cord & higher brain regions via neural circuits Relay motor information between cerebral cortex & cerebellum
  4. 4. PONS PONS M C P Length – 2.5 cm External features .. 1. Dorsal & ventral surfaces… - transvereslystriated 2. Basilar sulcus (vertical) .. Lodges Basilar Artery. 3. Dorsal surface forms upper part of floor of 4th Ventricle. 5. Laterally .. Continuous with Middle Cerebellar Peduncle - trigeminal nerve 6. Superior border - 3rd ,4th 7. Inferior border .. With 6th, 7th & 8th C.N. BASILAR GROOVE
  5. 5. PONS External features Cerebello-pontine angle Facial Colliculus Vestibular Area
  6. 6. MID BRAIN PONS 4th ventricle PONS Posterior surface 6th C.N. 7th C.N. 8th C.N. Anterior surface 5th C.N.
  7. 7. Lower part Upper part Internal features • By 2 sections. • (1) At lower part of medulla Fascial Colliculus • (2) At upper part At motor & Sensory Nucleus of Trigeminal nerve
  8. 8. • The pons is divisible into - ventral part (basilar) & dorsal part (Tegmentum). Ventral (basilar) part - The basilar (ventral) part has a uniform structure throughout length of pons. - contains transverse and vertical fibres & Pontine nuclei. (i) Transverse fibres are the pontocerebellar fibres- cross the midline to enter the opposite middle cerebellar peduncle. (ii) The vertical fibres - - Some of them descend from cerebral cortex to end in the pontine nuclei. (corticopontine) - Corticospinal fibres that descend through the pons in to the medulla . - Corticonuclear fibres end in the motor nuclei of cranial nerves mainly of opposite side. Internal = Basilar & Tegmental Part -The basilar (Ventral) part - Uniform structure throughout -Tegmentum (dorsal) part - Differs in upper & lower part of pons.
  9. 9. C.S. at Fascial Colliculus
  10. 10. C.S. of At motor & Sensory Nucleus of Trigeminal nerve
  11. 11. Basilar Part
  12. 12. VENTRAL (BASILAR) PART
  13. 13. Ventral(Basilar)PartPons GREY MATTER Pontine nuclei: Afferents - Corticopontine fibres of the same side. Efferents - Pontocerebellar fibres that cross the midline & pass through the middle cerebellar peduncle to enter the cerebellum. (Cortico-ponto-cerebellar pathway) Middle cerebellar peduncle
  14. 14. WHITE MATTER Longitudinal fibres:- Corticospinal and Corticonuclear (pyramidal) tracts. Transverse fibres:- Pontocerebellar Going to opposite half of cerebellum through middle cerebellar peduncle Ventral(Basilar)PartPons
  15. 15. Tegmentum of pons (dorsal part) Differs in upper & lower part of pons
  16. 16. C.S. at Facial Colliculus Abducent Nucleus Motor Nucleus of Facial Nerve Internal genu - Facial Colliculus Neurobiotaxis ?
  17. 17. C.S. at Facial Colliculus Superior salivatory Nucleus Lacrimatory Nucleus Nucleus Tractus Solitarius – Upper End
  18. 18. C.S. at Facial Colliculus Vestibular Nucleus Spinal Nucleus & Spinal Tract of V
  19. 19. Superior Olivary Nuclear Complex Principal Superior Olivary Nucleus Accessory Superior Olivary Nucleus Retro - Olivary Nucleus
  20. 20. Central Tegmental Tract
  21. 21. C.S. at Facial Colliculus
  22. 22. C.S. at Facial Colliculus
  23. 23. Middle Cerebellar Peduncle Inferior Cerebellar Peduncle
  24. 24. C.S. at Facial Colliculus Dorsal Cochlear Nucleus Ventral Cochlear Nucleus
  25. 25. Juxta Restiform Body Vestibular Nucleus
  26. 26. C.S. of At motor & Sensory Nucleus of Trigeminal nerve
  27. 27. Trigeminal nuclie – Motor & Sensory
  28. 28. Nucleus Ceruleus
  29. 29. Trigeminal nuclie – Motor & Sensory
  30. 30. Trigeminal nuclie – Motor & Sensory Trigeminal Ganglion
  31. 31. Muscles of Mastication Tensor Tympani Tensor veli Palatini Ant Belly of Digastric Motor Nucleus Of V Nerve
  32. 32. Sensory Nuclei Of Vth Nerve Spinal Nucleus Pain & Temperature Mesencephalic - Proprioceptive Principal Sensory Touch & Pressure From- Ipsilateral Face 1st Order Neuron
  33. 33. Sensory Nuclei Of V Nerve
  34. 34. Pain & Temperature Spinal Nucleus Of V Nerve
  35. 35. Efferent: - Ventral trigemino thalamic tract (Trigeminal Lemniscus) - Terminate : VPM of Thalamus Nuclie Of V Nerve VPM
  36. 36. Vestibulo-cochlear Nerve 8th C.N.
  37. 37. Vestibulo-Component Inferior Superior
  38. 38. Vestibular-Component
  39. 39. Afferent
  40. 40. Efferent – 1. MLF • Intrduction / Definition • Extent • Formation • Function • Applied – MLF Syndrome – Ipsilateral palsy of medial rectus – Contralateral Mononuclear horizontal nystagmus on adduction of eye
  41. 41. Efferent – 2. Cerebellum
  42. 42. Efferent – 3. Hair Cells of Macula & Ampullary crest Modulation Of Sensory Input
  43. 43. Efferent – 4. Spinal Cord
  44. 44. Cochlear-Component Auditory Pathway
  45. 45. Afferent:
  46. 46. Efferent:
  47. 47. Efferent:
  48. 48. Efferent: Area 41, 42
  49. 49. Blood supply: Pontine branch of Basilar artery Anterior cerebellar artery Inferior cerebellar artery & Superior cerebellar artery. Venous Drainage Into: Inferior petrosal sinus and Basilar plexus. PONS
  50. 50. LESION OF PONS: Cerebello – Pontine Syndrome Due to: Acoustic neuroma of vestibular nerve Compress angle
  51. 51. Cerebello – Pontine Syndrome 1. VIII Nerve Persistent tinnitus, Progressive Deafness Nystagmus, Nausea, Vomiting and Vertigo. 2. Cerebellar Lesions Ipsilateral cerebellar signs e.g.,Tremor,Ataxia, Dysmetria (Past Pointing) 3.Spinaltrigeminalnucleusandtract: Ipsilaterallossofpainandtemperaturesensationfromthe face(facialhemianesthesia) 4.FacialNerve: IpsilateralBellsPalsy, Hyperacusis,LossofTaste
  52. 52. Raymond’s Syndrome = Alternating Abducent Hemiplegia Occlusion of Paramedian branches of Basilar artery 1. 6th Nerve Ipsilateral paralysis of lateral rectus – Internal Squint 2. Pyramidal Tract Contralateral Hemiplegia
  53. 53. Millard - Gubler Syndrome = Alternating Facial Hemiplegia Occlusion of Paramedian branches of Basilar artery 1. 7th Nerve IpsilateralBellsPalsy, Hyperacusis,LossofTaste 2. Pyramidal Tract Contralateral Hemiplegia
  54. 54. Alternating Trigeminal Hemiplegia 1. 5th Nerve - Ipsilateral loss of pain and tepmperature sensation from the face (facial hemianesthesia) - LMN paralysis of masticatory muscles 2. Pyramidal Tract Contralateral Hemiplegia
  55. 55. THANK YOU

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