1. Brainstem By Dr Manah Chandra Changmai IMS

3. Consists of the midbrain, pons, andmedulla oblongata.

5. Ventral surface of brain stem Midbrain Pons Medulla oblongata

6. Ventral – Lateral View Midbrain Cerebral peduncles Pons Basis pontis Medulla

8. Vertical Columns of Cranial Nerves

9. Internal Columns of Nuclei

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 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)

11. Midbrain

13. Patterning of the Midbrain

15. Superior colliculi The roof of the aqueduct ( the tectum) contains the corpora quadrigemina 2 superior colliculithat control reflex movements of the eyes, head and neck in response to visual stimuli 2 inferior colliculithat control reflex movements of the head, neck, and trunk in response to auditory stimuli Inferior colliculi Corpora quadregemina Superior and inferior colliculiseperated by cruciform sulcus Superior colliculi larger and darker than inferior colliculi,the difference In colour due to superficial neurons in Superior colliculi

18. Substantianigra Cruscerebri

19. Cerebral aqueduct Basis pedunculi Substantianigra Cruscerebri (cerebral peduncle)

20. Internal Structure of Midbrain Cross section at inferior colliculus

24. Superior colliculus Edingerwestfal nucleus Occulomotor nucleus Red nucleus – relay from cortex and cerebellum to spinal cord, inferior olive, reticular formation, cerebellum Controls arm movement

26. Pons

31. Occupied predominately by reticular formation

32. Posterior surface help to form floor of fourth ventricle

33. The dorsal part is bounded laterally by inferior cerebellar peduncle in the lower part of the pons and superior cerebellar peduncle in upper part. DORSAL PART Upper pons

34. Dorsal surface of pons Six ascending tract 1 Dorsal and ventral cochlear nuclei – Receives auditory input from the cochlea through CN 8 2 Trapezoid body – Formed by decussating fibres of the ventral cochlear nuclei 3 Superior olivary nucleus – Auditory relay nucleus that receives input from the cochlear nuclei and contributes to lateral lemniscus 4 Lateral lemniscus » Auditory pathway that conducts most contralateral cochlear input 5 Medial lemniscus » Spinal afferent pathway 6 Spinal lemniscus » Spinal afferent pathway

35. 4th Ventricle Connection of pons to cerebellum Restiform body (inf. cerebellar peduncle) Middle cerebellar peduncle Medial lemniscusAscending 2nd order sensory neurons Descending upper motor neurons

39. Cranial Nerves of Lower Pons Vestibular Nuclei Pure sensory  lateral location Balance

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

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

42. Mid Pons Lateral lemniscus Trapezoid body fibers from dorsal column (position and vibration) Medial leminiscus fibers from dorsal column (position and vibration) Pontine nuclei Trapezoid body : transverse fibers in pontinetegmentum

43. Mid Pons Medial lemniscusfibers from dorsal column (position and vibration) Motor trigeminal nucleus Trigeminal tractpain, temperature, touch from contralateral face Principal trigeminal sensory nucleus Cranial nerve nuclei and Lemniscal sensory system – in tegmentum of the pons

46. Upper Pons Periaqueductal gray matter Medial longitudinal fasciculus Superior cerebellar peduncle decussation Transverse ponto-cerebellar fibers

47. Upper Pons Pediculopontine Nucleus Locus ceruleus Parabrachial Nucleus Some neurons release acetylcholine Other neurons release glutamate They assist in learning and voluntary motor control, e.g. locomotion, saccadic e

48. MEDULLA OBLONGATA

50. Becomes the spinal cord at the level of the foramen magnum.

52. Anterior median fissure

53. Posterior median fissureMedulla oblongata Spinal cord

57. Pyramid Olive Anterolateral fissure Anterior median fissure

59. DORSAL SURFACE OF MEDULLA OBLONGATA Floor of fourth ventricle Obex Gracile tubercle Posterior median sulcus Posterior median fissure Cuneate tubercle

60. Internal Structure of Medulla Cross section at three levels Level of pyramidal decussation

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

62. Internal Structure of Medulla Cross section at level of lemniscaldecussation

63. Level of LemniscalDecussation Gracile nucleus Medial longitudinal fasciculus Cuneate nucleus Medial lemniscus Carries 2nd order sensory neurons to VPL thalamus Internal arcuate fibers

64. Cross section at level of Level ofinferior olivary nuclei

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

66. Cranial Nerves of the Medulla N. solitarious Sensory nucleus for CN VII, IX, X Vestibular nuclei Posterior 1/3 of the tongue Dorsal motor nucleus of X N. ambiguus Motor nucleus for CN IX, X & XI Spinal trigeminal tract CN V, VII, IX, X Stylopharyngeus (lifts pharynx) Sensation behind ear

67. 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 N. ambiguus Motor nucleus for CN IX, X & XI Stylopharyngeus (lifts pharynx) Spinal trigeminal tract CN V, VII, IX, X Sensation behind ear

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

69. Mnemonic Out On Our Table Top Are Fruits, Very Green Veggies And Hamburgers

70. The End