1. BRAINSTEM

2. Structural Overview of Brainstem
Midbrain, pons, medulla
functions

3. BRAINSTEM
DORSAL SURFACE
VENTRAL SURFACE

4. medulla Connects pons superiorly with spinal cord inferiorly
Conical in shape
The Central canal continues upward into the lower half of medulla, in the upper half of medulla it expands as the cavity of fourth ventricle

5. two parts: open and closed
an open part (close to the pons)
a closed part (further down towards the spinal cord).

6. Gross Anatomy Review Medulla - ventral
Anterior median fissure
Pyramids
Pyramidal decussation
Olive
Inferior cerebellar peduncle

7. Gross Anatomy Review Dorsal medulla Posterior median sulcus
Gracile tubercle
Cuneate tubercle.

9. Brainstem X-sections Caudal medulla Rostral medulla Caudal pons
Rostral pons
Caudal midbrain
Rostral midbrain

10. medulla 3 sections inside the medulla: Pyramidal decussation
Sensory decussation
Level of olive

11. Caudal medulla pyramidal decussation

12. CAUDAL MEDULLA (LEVEL OF PYRAMIDAL DECUSSATION)FG
DMS FC GN
ST5
Central grey
matter CN
SN5
Central canal
DSC PD
VSC P
VMF

13. CAUDAL MEDULLA (LEVEL OF PYRAMIDAL DECUSSATION)
DMS: Dorsal median sulcus
FG: fasciculus gracilis
GN: Gracile nucleus
FC: Fasciculus cuneatus
CN: Cuneate nucleus
SN5: Spinal nucleus of trigeminal nerve
ST5: Spinal tract of trigeminal nerve
P: Pyramid
PD: Pyramidal decussation
DSC: Dorsal spinocerebellar tract
VSC: Ventral spinocerebellar tract
VMF: Ventral median fissure

14. CAUDAL MEDULLA (LEVEL OF PYRAMIDAL DECUSSATION)
GREY MATTER:
Sensory nuclei: Gracile, cuneate, spinal nucleus of trigeminal
WHITE MATTER:
Ascending tracts: Gracile, cuneate, spinal tract of trigeminal, dorsal & ventral spinocerebellar, spinal leminiscus
Descending tracts: Pyramidal & extrapyramidal tracts

15. CAUDAL MEDULLA (LEVEL OF PYRAMIDAL DECUSSATION)
Pyramidal decussation: Most of the fibers of pyramid decussate then pass laterally & dorsally to form the lateral corticospinal tract that descend in the lateral white column of spinal & terminate in ventral horn cells of opposite side
Spinal nucleus of trigeminal: It lies in the lower part of pons, the whole medulla & extends to the 2nd cervical segment of spinal cord where it is continuous with substantia gelatinosa. It receives pain & temperature sensations from the face along trigeminal nerve

16. CAUDAL MEDULLA (LEVEL OF PYRAMIDAL DECUSSATION)
Dorsal & ventral spinocerebellar tracts: They carry proprioceptive fibers to the cerebellum through inferior cerebellar peduncle (dorsal) & superior cerebellar peduncle (ventral)
Gracile &Cuneate tracts: They carry proprioceptive sensations & end in Gracile & Cuneate nuclei (2nd order neurones in dorsal column tract)

17. MID MEDULLA (LEVEL OF SENSORY DECUSSATION)
DMS FG
Central grey
matter FC GN CN
Central canal
ST5
SN5
Internal
Arcuate Fibers
DSC M L
VSC
Sensory
Decussation P
VMF

18. MID MEDULLA (LEVEL OF SENSORY DECUSSATION)
Gracile & cuneate nuclei: They are more prominent. Axons of cells of gracile & cuneate nuclei curve around the central canal as internal arcuate fibers then decussate forming the sensory decussation & ascend in the brain stem as medial leminiscus that end in the ventral posterolateral nucleus of thalamus
Pyramid: They are more prominent

19. MID MEDULLA (LEVEL OF SENSORY DECUSSATION)
GREY MATTER:
Sensory nuclei: Gracile, cuneate, spinal nucleus of trigeminal
WHITE MATTER:
Ascending tracts: gracile, cuneate, spinal tract of trigeminal, dorsal & ventral spinocerebellar, spinal leminiscus
Descending tracts: Pyramidal & extrapyramidal tracts

20. Caudal medulla int arcuate fibers
gracile & cuneate nuc & fasc
Int arcuate fibers – ML
MLF
Nucleus of spinal tract of trigeminal nerve
Inferior olivary nuc
Pyramids
Hypoglossal nuclei

22. Rostral medulla inf olivary nuc
olivary nuclear complex
Vestibulocochlear nuclei
Nucleus ambiguus
Hypoglossal nerve, dorsal nucleus of vagus, vestibulocochlear, glossopharyngeal and accessory nuclei

23. ROSTRAL MEDULLA DCN 4TH V ICP VCN Vagus Nerve I.O. ML HypoglossalMV LV V H S
ICP
VCN M L F A D
Vagus
Nerve
I.O. ML M
Hypoglossal
Nerve P
VMF

24. ROSTRAL MEDULLA H: Hypoglossal nucleus V: Dorsal vagal nucleus
S: Nucleus solitarius
A: nucleus ambiguus
MV: Medial vestibular nucleus
LV: Lateral vestibular nucleus
DCN: Dorsal cochlear nucleus
VCN: Ventral cochlear nucleus
ICP: Inferior cerebellar peduncle
I.O.: Inferior olive
D: Dorsal accessory olive
M: Medial accessory olive
MLF: Medial longitudinal fascisulus
ML: Medial leminiscus
P: Pyramid
VMF: Ventral median fissure

26. ROSTRAL MEDULLA GREY MATTER:
Motor nuclei: Hypoglossal, dorsal vagal, nucleus ambiguus
Sensory nuclei: Nucleus solitarius, medial & lateral vestibular nuclei, dorsal & ventral cochlear nuclei, spinal nucleus of trigeminal
Extrapyramidal nuclei: Inferior olive, medial & dorsal accessory olive

27. ROSTRAL MEDULLA WHITE MATTER:
Ascending tracts: Medial leminiscus, spinal leminiscus, spinal tract of trigeminal, ventral spinocerebellar tract
Descending tracts: Pyramidal & extrapyramidal tracts
Both ascending & descending tract: Medial longitudinal fasciculus
Inferior cerebellar peduncle: fibers connecting medulla to cerebellum

28. ROSTRAL MEDULLA
Hypoglossal nucleus: It lies in the medial part of floor of 4th ventricle. It contains motor neurones innervating muscles of tongue (except palatoglossus) through hypoglossal nerve
Dorsal vagal nucleus: It lies in the floor of 4th ventricle , lateral to hypoglossal nucleus. It contains preganglionic parasympathetic neurones running in the vagus nerve
Nucleus Solitarius: It lies ventrolateral to dorsal vagal nucleus. It receive taste fibers from facial, glossopharyngeal & vagus nerves

29. ROSTRAL MEDULLA
Nucleus ambiguus: It lies dorsal to inferior olivary nucleus. It contains motor neurones innervating muscles of pharynx, palate & larynx through glossopharyngeal, vagus & cranial part of accessory nerves
Medial & lateral vestibular nuclei: They lie in the floor of 4th ventricle, lateral to dorsal vagal nucleus. They receive afferent fibers from vestibular nerve
Dorsal & ventral cochlear nuclei: They lie dorsal (dorsal nucleus) & lateral (ventral nucleus) to ICP. They receive afferent fibers from cochlear nerve

30. ROSTRAL MEDULLA
Olivary nuclear complex: It is formed of a large nucleus (inferior olive) & 2 smaller nuclei (medial & dorsal accessory olive).
Afferents: From cerebral and cerebellar cortex & spinal cord
Efferents: To cerebellum through ICP
Function: They are concerned with control of movement

31. ROSTRAL MEDULLA
Medial longitudinal fasciculus: It consists of both ascending & descending fibers:
Ascending fibers: connect vestibular nuclei to nuclei supplying extraoccular muscles (occulomotor, trochlear & abducent nuclei). It coordinates movements of head & eyes
Descending fibers: connect vestibular nuclei to nuclei of ventral horn of spinal cord (medial vestibulospinal tract). It control body posture & balance

32. ROSTRAL MEDULLA
Spinal leminiscus: It carries pain, temperature & touch sensations from the opposite side of body to ventral posterolateral nucleus of thalamus
Inferior cerebellar peduncle: It is formed of fibers connecting medulla to cerebellum

33. Level of Inferior Olives
Vestibular nuclei
Medial Inferior
Hypoglossal nucleus CN XII
Inferior cerebellar peduncle = Restiform body
Inferior olivary nuclei
MLF
Arcuate nuclei  pontine nuclei

34. Rostral medulla N. solitarious Dorsal motor nucleus of X
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

36. Cranial Nerves of the Medulla
Vestibular nuclei
CN XII

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

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

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

40. 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

41. 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

42. 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

43. 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

44. 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)

45. 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)

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

47. CN X: Vagus Nerve N. solitarious Spinal trigeminal tract
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

48. CN X: Vagus Nerve N. solitarious Spinal trigeminal tract
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

49. CN X: Vagus Nerve N. solitarious Spinal trigeminal tract
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

50. CN X: Vagus Nerve N. solitarious Dorsal motor nucleus of X
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

51. CN X: Vagus Nerve N. solitarious Dorsal motor nucleus of X
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

52. Pons Lies anterior to cerebellum Connects medulla to midbrain
1 inch long

53. Pons Landmarks Cranial Nerves
4th ventricle Cerebellum and Middle cerebellar peduncle Basilar groove
Cranial Nerves
Abducent, facial, vestibulocochlear, Trigeminal nerves

54. Ventral – Lateral View Midbrain Pons Medulla Cerebral peduncles
Basis pontis
Medulla
Pyramid Olive

56. Pons Posterior view Median sulcus Medial eminence Sulcus limitans
Facial colliculus
Area vestibuli

58. Pons
It is commonly divided into anterior part(basal part) and posterior part (tegmentum) by transversely running fibers of trapezoid body

59. Internal Structure of the Pons
Cross section at two levels
Level of facial nucleus (CN VII)
Level of trigeminal nuclei

60. Level of facial colliculus

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

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

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

65. 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

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

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

68. level of Upper Pons

69. Upper Pons
4th Ventricle
Middle cerebellar peduncle
Corticospinal tract, corticobulbar tract, corticopontine fibers
Descending fibers

70. Upper Pons Pontine nuclei in basis 4th Ventricle
Middle cerebellar peduncle
Pontine nuclei in basis

71. Upper Pons Pontine nuclei
Lateral lemniscus
Pontine nuclei
Trapezoid body – transverse fibers in pontine tegmentum

72. Lower Pons Pontine nuclei
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

73. Cranial Nerve of the upper Pons
4th Ventricle
CN V
Motor trigeminal nucleus

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

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

76. Upper Pons 4th ventricle  cerebral aqueduct
Superior cerebellar peduncle
Transverse ponto-cerebellar fibers
Descending upper motor neurons

77. Upper Pons
4th ventricle  cerebral aqueduct
MLF

78. Midbrain 0.8 inch in length
Connects Pons and cerebellum with the forebrain

79. cerebral aqueduct

80. EXTERNAL MORPHOLOGY
superior colliculus

81. EXTERNAL MORPHOLOGY
inferior colliculus

82. EXTERNAL MORPHOLOGY
CN.IV

83. EXTERNAL MORPHOLOGY
crus cerebri

84. interpeduncular fossa
EXTERNAL MORPHOLOGY
interpeduncular fossa

85. EXTERNAL MORPHOLOGY
CN.III

86. INTERNAL MORPHOLOGY-slide 16
cerebral aqueduct

87. External Structure of Midbrain
Optic chiasm
Interpeduncular fossa
Oculomotor nerve (CN III)
Trochlear nerve (CN IV)
Pons
crus cerebri
Ventral surface
(anterior)

89. Posterior view

90. Patterning of the Midbrain

91. Internal Structure of Midbrain
Cross section at two levels
Level of inferior colliculus
Level of superior colliculus

92. Lower Midbrain Inferior colliculus hearing cerebral aqueduct DORSAL
VENTRAL
Crus cerebri

93. Lower Midbrain Inferior colliculus Substantia nigra
Melanin-containing cells that produce dopamine Project to the basal ganglia, cerebral cortex, cerebellum, hypothalamus

94. Lower Midbrain Inferior colliculus Substantia nigra Crus cerebri

95. Lower Midbrain
Inferior colliculus
CN IV Trochlear nerve

96. Lower Midbrain
Inferior colliculus
CN IV Trochlear nerve
MLF

97. Lower Midbrain
Inferior colliculus
CN IV
MLF

98. Lower Midbrain
Inferior colliculus
hearing
Mesencephalic nucleus of V

100. Internal Structure of Midbrain
Cross section at two
Levels:
Level of inferior colliculus
Level of superior colliculus

101. Upper Midbrain Superior colliculus vision
Substantia nigra Crus cerebri

104. Upper Midbrain Vision Hearing
Superior colliculus  Lateral geniculate body
Hearing
Inferior colliculus  Medial geniculate body

105. Upper Midbrain Superior colliculus vision
Red nucleus – relay from cortex and cerebellum to spinal cord, thalamus, reticular formation, substsantia nigra

106. Cranial Nerves of Upper Midbrain
Superior colliculus
vision
Edinger Westfal nucleus
MLF
Red nucleus
CN III Oculomotor nucleus