Download Hypothalamus

Cerebellum
Developmental sequence of
brain
Fourth week
Fifth week
Location of cerebellum
Lies above
and behind
the medullar
and pons and
occupies
posterior
cranial fossa
Location of cerebellum
External structures
Consists of two cerebellar hemispheres united in the
midline by the vermis
Primary fissure
External structures
Lobules of cerebellum: Anterior lobe, posterior lobe, flocculonodular lobe.
Posterolateral fissure
External structures
• Tonsil of cerebellum
two elevated masses
on inferior surface of
hemispheric portion,
just nearby foramen
magnum
• Cerebellar tonsilar
hernia
Internal structures
• Cerebellar cortex – gray matter
Granular layer, piriform (Purkinje) cell layer, molecular layer
• Cerebellar medulla – white matter
Superior / Middle / Inferior cerebellar peduncles
• Cerebellar nuclei – gray matter within
white matter
Fastigial, globose, emboliform, dentate nuclei
Interposed nucleus
Cerebellar cortex
Molecular
layer
Piriform
cell layer
Granular
layer
White
matter
Cerebellar nuclei
Fastigial, globose, emboliform, dentate nuclei
Cerebellar peduncles
Cerebellar peduncles
superior cerebellar peduncle
(brachium conjunctivum) connects with
midbrain, contain mostly efferent fibers
middle cerebellar peduncle
(brachium pontis) connects with pons,
contain afferent fibers
inferior cerebellar peduncle (restiform
body) connects with medulla and with
spinal cord, contain both afferent and
efferent fibers
Functional divisions of cerebellum
Lateral zone
Intermediate zone
Vermis
• Vestibulocerebellum
– Archicerebellum
– Flocculonodular
lobe
• Spinocerebellum
– Paleocerebellum
– Vermis and
intermediate zone
• Cerebrocerebellum
– Neocerebellum
– Lateral zone
Flocculonodular lobe
Connections and functions of
cerebellum
Vestibulocerebellum
• Connections
– Afferents: receives inputs from vestibular
nuclei and vestibular ganglion
– Efferents: projects to the vestibular nucleus
→ vestibulospinal tract and medial
longitudinal fasciculus → motor neurons of
anterior horn and cranial nuclei innervating
extraocular muscles
Function: regulation of eyeball movements
and maintenance of body equilibrium.
Spinocerebellum
Connections
•
•
Afferents: receives somatic sensory information via
spinocerebellar tracts
Efferents:
• Vermis projects to the fastigial nucleus →
vestibular nuclei and reticular formation →
vestibulospinal tract and reticulospinal tract →
motor neurons of anterior horn
• Intermediate zone projects to the interposed
nuclei
– Contralateral red nucleus → rubrospinal tract →motor neurons of
anterior horn
– Contralateral VL of thalamus →cerebral cortex→ coticospinal
tract→motor neurons of anterior horn
• Function:
modulate the
muscular
tension.
Cerebrocerebellum
• Connections
– Afferents: receives input from the cerebral
cortex via a relay in pontine nuclei
– Efferents: projects to dentate nucleus → VL
of thalamus → primary motor cortex →
corticospinal tract → motor neurons of
anterior horn
• Function:
modulate the
coordination of
voluntary and
fineness
movement,
including
determination of
movement
strength, direction
and amplitude.
Cerebellar functions
• Cerebellum has functions of
1. maintaining body posture,
2. controlling muscular tension,
3. coordinating of voluntary movement,
but NOT initiating and performing
voluntary movement.
Cerebellar injury symptoms
Typical signs of
cerebellar injury:
a. Ataxia:
incoordination of
voluntary movement
b. Nystagmus: tremor
of eyeball
c. Intention tremor
Nose-to-finger test
Diencephalon
Location
Location
Located
between
midbrain and
telencephalon,
mostly
surrounded by
cerebral
hemispheres
Divisions of diencephalon
•
•
•
•
•
(dorsal) thalamus
metathalamus
epithalamus
subthalamus
hypothalamus
Dorsal thalamus
External features
•
•
•
•
•
•
A large egg-shaped
nucleus mass,
Right and left portion of
thalamus are joined by
interthalamic adhesion
Anterior end called
anterior thalamic
tubercle,
Posterior end called
pulvinar
Terminal stria
Hypothalamic sulcus
Dorsal thalamus
Subdivision
Ant. nuclear group
Principal Nuclei
Common
abbreviation
Anterior
Med. nuclear group dorsomedial
Lat. nuclear group
Dorsal layer
Lateral dorsal
LD
Lateral posterior
LP
Pulvinar
Ventral layer
Ventral anterior
Ventral lateral
(intermediate)
Ventral posterior
VA
VL (VI)
VP
Ventral posterolateral
VPL
Ventral posteromedial
VPM
Functional subdivision
Non-specific projecting nuclei ---- receive afferents from
olfactory brain and reticular formation of brain stem (ascending
reticular activating system), project to hypothalamus, corpus
striatum and diffusely to cerebral cortex.
• Midline nuclei
• Intralaminar nuclei
• Thalamic reticular nuclei
Internuncial nuclei ---- receive a wide variety of afferent fibers
and in turn project widely to association areas of cerebral cortex,
involved in higher nervous activity of brain.
• Anterior nuclear group
• Medial nuclear group
• Dorsal layer of lateral nuclear group
Functional subdivision
Specific relaying nuclei
• Ventral anterior nucleus (VA)
• Ventral lateral nucleus (VL)
Receive inputs from corpus striatum, dentate nucleus, and substantia
nigra, project to motor cortex to regulate body movement.
• Ventral posteromedial nucleus (VPM)
－receives trigeminal lemniscus and taste fibers
• Ventral posterolateral nucleus (VPL)
－receives medial lemniscus and spinal lemniscus
Projects to primary somatic sensory area via central thalamic
radiations
Metathalamus
Lateral geniculate body (LGN)
Medial geniculate body (MGN)
Specific relaying nuclei
Metathalamus
•
Medial geniculate body
(MGN)
–
–
–
•
Relay station of audition
Receive fibers from
(brachium of) inferior
colliculus
Projects to auditory area
via acoustic radiation
Lateral geniculate body
(LGN)
–
–
–
Relay station of vision
Receive fibers from retina
(optic tract)
Projects to visual area via
optic radiation
Epithalamus
Includes
• Thalamic medullary
stria
• Habenular trigone
• Habenular commissure
• Pineal body: Melatonin
• posterior commissure
Dorsal view
Subthalamus
• Ventrally to the dorsal
thalamus
• Contains subthalamic
nucleus involved in
movement regulation.
subthalamic
nucleus
Hypothalamus
Position－lies ventral to thalamus
Boundaries
• Superior: hypothalamic sulcus
• Inferior:
– optic chiasma
– tuber cinereum
– Infundibulum (hypophysis)
– mamillary body
• Anterior: interventricular foramen
•
Posterior: continues with midbrain
tegmentum
Hypothalamus
Hypothalamic divisions
Anterior to posterior
• Preoptic region
• Supraoptic region
• Tuberal region
• Mamillary region
A
P
Principal nuclei in hypothalamus
• Preoptic region: preoptic nucleus
• Supraoptic region
– Supraoptic nucleus
– Paraventricular nucleus
produce antidiuretic hormone (ADH or vasopressin) and
oxytocin
• Tuberal region
– Infundibular (Arcuate) nucleus
– Ventromedial nucleus
– Dorsomedial nucleus
• Mamillary region
– Mamillary nucleus
– Posterior hypothalamic nucleus
Paraventricular
nucleus
Anterior
commissure
Preoptic
nucleus
Anterior
hypothalamic
nucleus
Supraoptic
nucleus
Suprachiasmatic
nucleus
Optic
chiasma
Infundibulum
(stalk of the
pituitary gland)
Fornix
Dorsomedial
nucleus
Posterior
hypothalamic
nucleus
Lateral
hypothalamic
area
Arcuate
nucleus
Ventromedial
nucleus
Mammillary
body
Pituitary
gland
The main hypothalamic nuclei
Hypothalamus -- connection
• Connects with limbic system, brainstem, spinal cord and
dorsal thalamus
• Connects with hypophysis
Hypothalamus -- connection
• Supraoptic nucleus →
supraopticohypophysial tract → posterior lobe of
hypophysis (neurohypophysis)
• Paraventricular nucleus →
paraventriculohypophysial tract → posterior lobe
of hypophysis (neurohypophysis)
Hypothalamus -- connection
Parvicellular neurons in
the arcuate nucleus and
nearby region secrete
releasing and inhibiting
hormones →
tuberoinfundibular tract
→ portal vein of
hypophysis → anterior
lobe of hypophysis
Thyroidstimulating
hormone
Adrenocorticot
ropic hormone
Functions of hypothalamus
• Neuroendocrine center
• Subcortical higher regulatory center of the
visceral activity, such as
temperature regulation
food ingestion
reproduction
fluid and electrolyte balance
• Regulate emotional responses and biological
rhythms
Third ventricle
• Position: a narrow ventriclar
cleft lies within diencephalon
– Lateral wall: dorsal thalamus
and hypothalamus
• Communication
Lateral ventricles → third
ventricle →midbrain aqueduct →
fourth ventricle