1. The document describes the anatomy and functions of the cerebellum and fourth ventricle. It details the lobes and fissures of the cerebellum, the peduncles connecting it to other parts of the brainstem, and its role in motor control. 2. The fourth ventricle is located in the hindbrain between the cerebellum and pons/medulla. It communicates with the subarachnoid space through three openings and contains vital motor and sensory centers in its floor and walls. 3. Lesions of the cerebellum or surrounding structures can cause ataxia, tremors, and other movement disorders as well as impairments of balance, muscle tone,

1. Prof Soumya Chakraborty Bhattacharya
HoD Anatomy, ESI-PGIMSR Joka Kolkata, MEU Coordinator, Member
Secretary Ethics
MBBS(Cal Univ),MS(BHU), FAIMER Institute (USA),ACME(Wardha), Cert. Bioethics(Manipal Univ)
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2.  Latin for "little brain“:
dorsal part of
hindbrain:
Rhombencephalon
 Posterior cranial fossa:
cerebellar fossa of
squamous part of
occipital bone
 Ipsilateral motor
control on body
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3.  Below occipital lobe of
cerebrum separated
by tentorium cerebelli
 Anteriorly: Dorsal
surface of pons and
medulla separated by
4th ventricle
 Arbor Vitae Cerebelli:
Arrangement of white
matter in vermis and
hemispheres:
branches of a tree
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4.  Two lateral halves-
Hemispheres
 Intermediate part-
Vermis
 Superior and Inferior
surfaces
 Anterosuperior
aspect: Superior
Cerebellar notch
 Posteroinferior
aspect: Posterior
cerebellar notch
related to Falx
Cerebelli
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5.  Superior Vermis:
 Midline ridge
 Narrow and shallow
linear depressions- 3
Fissures: Primary,
Horizontal,
Posterolateral
 3 lobes: Anterior:1/3,
Posterior:2/3,
Flocculonodular
Lobes
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6.  Depression :
inferior vermis :
Vallecula
 Superior and
inferior halves of
middle lobe
separated by
Horizontal fissure
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7.  Lingula- No lateral
extension
 Central Lobule- Ala
 Culmen- Anterior
Quadrangular
Lobule
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8.  Declive- Posterior
Quadrangular
Lobule
 Folium- Superior
Semilunar Lobule/
Lobulus Simplex
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9.  Tuber- Inferior
Semilunar Lobule
 Pyramid- Biventral
Lobule
 Uvula- Tonsil
 Horizontal Fissure
divides cerebellum into
superior
(Proximal) and inferior
(Distal)halves
 Nodule-
Flocculonodular Lobe:
Flocculus
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10.  Compact masses of Gray
matter in core of white
matter
 4 : either side of midline
 Lateral to Medial:
Dentate: lateral and largest
Emboliform: oval Globose:
round
Fastigial: in white core of
vermis
Emboliformis and Globosus
: Nucleus Interpositus
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11.  Archicerebellum:
Most primitive
Lingula,Flocculonodul
ar lobe, Fastigial
Nucleus
Vestibulocerebellar
fibers
Maintains equilibrium
or balance
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12.  Paleocerebellum:
Central Lobule and
Ala, Culmen and
Anterior
Quadrangular Lobule,
Pyramid, Uvula,
Nucleus Interpositus
Spinocerebellar fibers
Maintains muscle tone
and posture
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13.  Neocerebellum:
Middle/Posterior lobe
except Pyramid and
Uvula
Dentate Nucleus
Corticopontocerebellar
Coordination of
voluntary smooth
and skilled
movements
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15.  Superior, Middle,
Inferior Cerebellar
Peduncles
connecting
Midbrain, Pons,
Medulla :
Cerebellopetal and
Cerebellofugal
fibers
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16.  Thinnest
 Afferent:Ventral
Spinocerebellar,
Tectocerebellar
tracts
 Efferent:
Dentatorubral,
Dentatothalamic
tracts
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17.  Thickest with only
Afferent Fibers
 Pontocerebellar
Fibers
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18.  Afferent: Dorsal
Spinocerebellar, Ant
and Post External
Arcuate,
Cuneocerebellar,
Parolivocerebellar,
Olivocerebellar,
Vestibulocerebellar,
Reticulocerebellar
Fibers
 Efferent:
Cerebelloolivary,
Cerebellovestibular,
Cerebelloreticular
tracts
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19.  Afferent Fibers: Enter
Through Superior,
Middle and Inferior
Cerebellar Peduncles
 Efferent Fibers: Leave
Through Superior
and Inferior
Cerebellar Peduncles
 Intrinsic Fibers: Exit
within Cerebellum
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20.  3 arteries
 Superior Cerebellar
Artery: SCA
 Anterior Inferior
Cerebellar Artery:AICA
 Posterior Inferior
Cerebellar Artery:PICA
 SCA: Cerebellar cortex,
Nuclei and Superior
Cerebellar Peduncles
 AICA: Anterior portion of
Inferior cerebellum and
Middle Cerebellar peduncles
and Facial and
Vestibulocochlear nerves
 PICA:Posterior inferior
portion of cerebellum,
Inferior Cerebellar
Peduncles, Nucleus
ambiguus,Vagus, Spinal
Trigeminal Nucleus, Solitary
Nucleus and
Vestibulocochlear Nuclei.
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21.  Ipsilateral control of
body
 Maintains equilibrium
of body/balance
 Muscle tone and
body posture
 Smooth coordination
and Skilled
movements
 Congenital:
Hypoplasia/Dysgenesis
 Traumatic
 Ischaemic: Thrombosis
of any cerebellar art
 Degenerative: Multiple
Sclerosis
 Neoplastic:
Medulloblastoma and
other Expanding
tumors
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22.  Lesion of Archicerebellum: Flocculonodular lobe
and Lingula/ Vermis Syndrome
 Common cause: Medulloblastoma of children
 Disorders in equilibrium:
*Unsteadiness in balance: Positive Romberg’s Sign
*Unsteadiness in Gait: Sway side to side:Stagger
*Unsteady Head: Unable to keep head erect:
Moving forwards and backwards
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23.  Combined effects of lesions: Paleo and
Neocerebellum
 Impaired functions of paleocerebellum:
Hypotonia- Loss of resilience of muscle, early
fatigue – Asthenia
 Excessive movement of terminal joints due to
loss of stretch reflex: Pendulous Knee Jerk
 Postural defect: Head rotated and flexed,
shoulder on a lower level on affected side
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24.  Impaired functions of Neocerebellum:
 Incoordination or Asynergy of smooth and
precise voluntary movement: Cerebellar Ataxia
 Intention Tremor: Abnormal Repetitive,
Oscillatory movement affecting distal part of
limbs-hands and fingers: picking up object,
buttoning clothes
 Dysmetria: Finger Nose Test Target:Pastpointing
 Loss of harmonization of groups of muscles:
Decomposition of movements
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25.  Dysdiadochokinesia: Incoordination between
functions of antagonistic muscles: Repeated
pronation and supination- slow and jerky,
incoordination
 Dysarthria: Disorder in articulation of speech due
to incoordination of muscles of larynx, tongue
and lips: Slurred speech
 Nystagmus: Incoordination of movement of
extraocular muscles with rhythmical oscillation of
eyeball while fixing the gaze for an object for
long: Horizontal side to side movement: sudden
jerk in eyeball when gaze returned back
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27.  Cavity of hindbrain
 Diamond shape, Lined by
ependyma
 Ventricular system consist of left
and right lateral ventricles, third
ventricle, and fourth ventricle.
 Extends from cerebral aqueduct
(aqueduct of Sylvius) to obex,
filled with CSF
 Located within pons or upper part
of medulla oblongata
 CSF entering fourth ventricle
through cerebral aqueduct
 exit to subarachnoid space of
spinal cord through two lateral
apertures and a single,
midline median aperture.
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28.  t shaped
 Lower half of roof: double
layered pia mater with
branches of posterior
inferior cerebellar artery
lines over ependyma form
tela choroidea
 Communicates dorsally
with subarachnoid space
through three apertures:
a) Foramen of Magendie –
midline foramen in lower
part of roof
B) Foramen of Luschka:
Lateral angles of cavity
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29.  Above with 3rd
Ventricle: through
Aqueduct of Midbrain
 Below with Central
Canal of Spinal Cord
through narrow lower
part of Medulla
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30.  Superior portion of roof (i.e.
posterior edge) thin lamina -
superior medullary velum -
connecting left and
right superior cerebellar
peduncles together: Like a tent
 Inferior portion of roof -
Inferior medullary velum-
directed caudally and laterally
formed by Cerebellum
 3 corners of inferior roof :
foramen Magendie
and Foramina of Luschka.
 Roof rises like a
peak/fastigium - Fastigial
nucleus lies
 Caudal tip : Central canal -
known as Obex, marker for
level of foramen magnum , tip:
Calamus Scriptorius
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31.  Side walls formed by: Cerebellar
Peduncles
 Rhomboid fossa
 Median sulcus - Cerebral aqueduct to
Central Canal of Spinal Cord, dividing
floor into right and left halves
 Each half divided by Sulcus Limitans
within floor, motor neurons located
medially while sensory neurons laterally
 Elevation between median sulcus and
sulcus limitans (i.e. region for motor
neurons): medial eminence
 Lateral region : vestibular area
 Sulcus limitans bifurcates at either end
- superior fovea cranially and inferior
fovea caudally.
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32.  Pons located behind middle
and superior portion of floor
 Superior region of pons
Locus coeruleus -
concentration
of noradrenaline : sky
blue appearance, superiorly
to superior fovea
 Internal part of facial nerve
bulges into ventricle,
forming facial colliculus,
looping around abducens
nucleus within inferior
region of Pons.
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33.  medulla oblongata behind inferior
portion of floor
 Medullary striae run transversely
across floor
 hypoglossal nucleus bulges into
floor, creating hypoglossal trigone,
located slightly superiorly to inferior
fovea, within the median eminance.
 dorsal nucleus of vagus nerve
bulges—vagal trigone—overlies
region inferior of inferior fovea.
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34.  Intracranial ependymomal , Cerebello Pontine Angle tumors
 Presence of vital centers in brain stem and cerebellum
surrounding 4th ventricle
 CSF Circulation
 Medulloblastoma in children: Undifferentiated
neuroectodermal cells of vermis of cerebellum: Pressure on
vital centers with hypoglossal and vagal triangles: Disorders of
CVS functions, difficulty of Respiration, Swallowing,Movements
of tongue, disorder related to equilibrium, balance, hypotonia
and incoordination of movements
 Occlusion: Obstruction of foramina interfere with free
circulation of CSF from ventricular cavity - dilatation of
ventricular system due to over accumulation of CSF: Internal
Hydrocephalus
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