Transcript Anterior lobe

CEREBELLUM
D.Nimer
D.Safaa
D.Rania Gabr
D.Elsherbiny
Objectives
• Identify the major lobes and regions of cerebellum.
• Summarize the structure of the cerebellar cortex
• Identify the deep cerebellar nuclei and their
connections.
• List the afferent and efferent connections of the
cerebellum and their arrangement in cerebellar
peduncles.
• Describe the major functions of the cerebellum and
how each side of the cerebellum controls the ipsilateral
side of the body.
• Explain the effects of lesions of cerebellum and motor
disorder associated with cerbellar lesions.
- Lies behind Pons &
Medulla
- Situated in the posterior
cranial fossa
- It is covered by “tentorium
cerebelli “
EXTERNAL FEATURES
 Its surface is highly
convoluted forming the
gyri called Folia,
separated by Fissures.
 It consists of two
Cerebellar Hemispheres
joined in midline by the
Vermis.
Inferior
vermis
EXTERNAL FEATURES
• Folia: Transversely oriented folia or gyri
• 3 lobes in each hemisphere: Anterior, Posterior, Flocculonodular
• Neural arrangement: Gray matter (Cortex), White matter (Internal),
• Arbor vitae (tree of life): distinctive treelike pattern of the white
matter
Folium
CONNECED TO THE
BRAIN STEM BY:
1.
Posterolateral fissure
in front of primary fissure, on the superior surface.
(middle) lobe behind primary fissure (Between
Primary & posterolateral )
: in front of Posterolateral
Posterolateral fissure
Anterior lobe
Posterior lobe
Flocculonodular lobe
Structure of the cerebellum
1.
2.
3.
•
•
•
•
Outer grey matter: cerebellar cortex.
Inner white matter: cerebellar medulla.
Deeply seated nuclei (grey matter) in white matter: from medial to
lateral:
Fastigeal nucleus.
Globose nucleus.
Emboliform nucleus.
Dentate nucleus: largest one.
V
E
R
M
A
L
Z
O
N
E
= Paravermal zone
CEREBELLAR CONNECTIONS
AFFERENT FIBERS
INFERIOR CEREBELLAR PEDUNCLE
A. Restiform Body: It contains:
1. Olivocerebellar fibers: from the
inferior olivary nucleus of the opposite
side. It carries information from the
spinal cord and the cerebral cortex for
the control of movement. Terminates
as climbing fibers to cerebellar cortex.
2. Dorsal spinocerebellar tract: from
Clarke’s nucleus of the same side. It
carries proprioceptive information from
the TRUNK AND LOWER LIMB.
3. Cuneocerebellar tract (dorsal external
arcuate fibers): from the accessory
cuneate nucleus of the same side. It
carries proprioceptive information from
the UPPER LIMB.
3. Arcuatocerebellar fibers: from
the arcuate nuclei of the 2 sides.
They reach the cerebellum by the
ventral external arcuate fibers and
stria medullaris of the 4th ventricle.
4. Reticulocerebellar tract: from
the reticular formation. It carries
motor information from the
cerebral cortex and sensory
information from the spinal cord.
5. Trigeminocerebellar tract: from
the spinal nucleus and the main
sensory nucleus of the trigeminal
nerve. It carries sensory
information from the face.
B. Juxtarestiform Body:
1. Vestibulocerebellar fibers:
From the vestibular nerve and vestibular nuclei for maintaining equilibrium.
2. Cerebellovestibular Fibers:
To the vestibular nuclei to maintain the equilibrium and regulate muscle tone.
3. Cerebelloreticular Fibers:
To the reticular formation to maintain equilibrium and regulate the muscle tone.
MIDDLE CEREBELLAR PEDUNCLE
It contains pontocerebellar
fibers only (arise from the
pontine nuclei of the
opposite side).
SUPERIOR CEREBELLAR
PEDUNCLE
AFFERENT FIBERS:
1. Ventral spinocerebellar tract: It carries proprioceptive
information from the muscles of the lower limb.
2. Tectocerebellar tract: from the tectum. It carries visual and
auditory stimuli.
3. Trigeminocerebellar tract: from the mesencephalic nucleus of
the trigeminal nerve. It carries proprioceptive information from
the muscles of the face, eye and palate
Efferent Fibers:
1. Dentatorubral tract: to red nucleus of the opposite side to
regulate the muscle tone.
2. Dentatothalamic tract: to the ventral lateral thalamic
nucleus of the opposite side for moment-to-moment
control of movement.
Functions of cerebellum
 Maintenance of Equilibrium
- balance, posture, eye movement
 Coordination of half-automatic movement of
walking and posture maintenace
- posture, gait
 Adjustment of Muscle Tone
 Motor Leaning – Motor Skills
 Cognitive Function
CEREBELLAR LESIONS
1. Intention tremor: the tremor is absent at rest. It
appears when the patient moves his limb.
2. Incoordination:
a) Ataxia Ipsilateral: is due to incoordination of the
lower limb muscles.
b) Nystagmus: rapid jerky eye movements due to
incoordination of the extraocular muscles.
3. Disturbance in the range of movement
(dysmetria): inability to measure distances.
Cerebellar
Ataxia
Ataxic gait and
position:
Left cerebellar tumor
a. Sways to the right in
standing position
b. Steady on the
right leg
c. Unsteady on the
left leg
d. ataxic gait
Remember:
IPSILATERAL