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Neuroanatomy © by Matthias Heyner 2008
Neuroanatomy
The four Parts of the diencephalon
Part
Epithalamus
Boundary line
Structure
 Pineal gland
 Habenulae
Function
Regulation of circadian
rhythms, linking of olfactory
system to brainstem
Dorsal diencephalic
sulcus
Thalamus

Thalamus
Relay of sensory information;
assistance in regulation of
motor function

Subthalamic
nucleus
Zona incerta
Globus Pallidus
Relay of sensory information
(somatomotor zone of
diencephalon
Optic chiasm, optic
tract
Tuber cinereum,
neurohypophysis
Mammillary bodies
Coordination of autonomic
nervous system with
endocrine system;
participation in visual
pathway
Middle diencephalic
sulcus
Subthalamus


Ventral diencephalic
sulcus
(=hypothalamic
sulcus

Hypothalamus


Nomenclature of the thalamic nuclei
Name
Specific thalamic nuclei
(cortically dependent)
Nonspecific thalamic nuclei
(cortically independent)
Integration nuclei
Alternative
Name
Palliothalamus
Properties
Project to the cerebral cortex (pallium)
Project to brainstem, diencephalon and corpus
striatum
Project to other nuclei within the thalamus
(classified as nonspecific thalamic nuclei)
Intralaminar nuclei
Nuclei in the white matter of the internal
medullary lamina (classified as nonspecific
thalamic nuclei)
Synopsis of some clinically important connections of specific thalamic nuclei
Thalamic afferents (structures
that project to the thalamus)
Mammillary Body
(mammillothalamic fasciculus)
Cerebellum, red nucleus
Truncothalamus
Thalamic nucleus
(abbreviation)
Anterior nucleus (NA)
Thalamic efferents (structure to
which the thalamus projects)
Cingulate gyrus (limbic system)
Ventral lateral nucleus (VL)
Premotor cortex (areas 6aα
and 6aβ)
Posterior funiculus, lateral
funiculus (somatosensory
Ventral posterolateral nucleus
(VPL)
Postcentral gyrus (sensory
cortex) = somatosensory cortex
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Neuroanatomy © by Matthias Heyner 2008
input, limbs, trunk)
Trigeminothalamic tract
(somatosensory input, head)
Inferior brachium (part of the
auditory pathway)
Optic tract (part of the visual
pathway
Functions of the hypothalamus
Ventral posteromedial nucleus
(VPM)
Medial geniculate nucleus
(body) (MGB)
Lateral geniculate nucleus
(body) (LGB)
Postcentral gyrus (sensory
cortex) = somatosensory cortex
Transverse temporal gyri
(auditory cortex)
Striate area (visual cortex)
Region or Nucleus
Anterior preoptic region
Function
Maintain constant body temperature; Lesion:
central hypothermia
Posterior region
Respond to temperature changes, e.g., sweating;
Lesion: hypothermia
Midanterior and posterior regions
Activate sympathetic nervous system
Paraventricular and anterior regions
Activate parasympathetic nervous system
Supraoptic and paraventricular nuclei
Regulate water balance; Lesion: Diabetes
insipidus, also lack of thirst response resulting in
hyponatremia
Anterior nuclei:
Regulate the appetite and food intake:
 Medial part
 Lesion: Obesity
 Lateral part
 Lesion: Anorexia and emaciation
Hormones of the anterior pituitary lobe (adrenohypophysis)
Hormones and synonyms
Somatotropin (STH)
Growth hormone (GH)
Somatotropic hormone
Prolactin (PRL o LTH)
Cell designation*
Somatotropic (a)
Follitropin (FSH)
Follicle-stimulating hormone
Gonadotropic (b)
Lutropin (LH)
Interstitial cell stimulating
hormone – ICSH
luteinizing hormone
Gonadotropic (b)
Thyrotropin (TSH)
Thyroid stimulating hormone
Thyrotropic hormone
Thyrotropic (b)
Corticotropin (ACTH)
Adrenocorticotropic hormone
Adrenotropic (b)
Mammotropic (a)
Hormone actions
Stimulates longitudinal growth;
acts on carbohydrate and lipid
mechanism
Stimulates lactation and
proliferation of glandular
breast tissue
Acts on the gonads; stimulates
follicular maturation,
spermatogenesis, estrogen
production, expression of
lutropin receptors and
proliferation of granulose cells.
Triggers ovulation; stimulates
proliferation of follicular
epithelial cells, production of
testosterone in interstitial
Leydig cells of the testis, and
synthesis of progesterone, has
general anabolic activity
Stimulates thyroid gland
activity; increases O2
consumption and protein
synthesis; influences
carbohydrate and lipid
metabolism
Stimulates hormone production
in adrenal cortex; influences
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Neuroanatomy © by Matthias Heyner 2008
Alpha/beta Melanotropin
(MSH)
Melanotropic (b)
water and electrolyte balance;
acts on carbohydrate formation
in liver
Aids in melanin formation and
skin pigmentation; protects
against UV radiation**
*Cells are classified as either acidophilic (a) or basophilic (b)
**In human, melanotropin serves as a neurotransmitter in various brain regions.
Overview of the nuclei of cranial nerves III-XII
Motor nuclei: give rise to efferent (motor)
fibers
Somatic efferent or somatic motor nuclei:
 Nucleus of oculomotor nerve (CN
III)
 Nucleus of trochlear nerve (CN IV)
 Nucleus of abducent nerve (CN VI)
 Nucleus of accessory nerve (CN XI)
 Nucleus of hypoglossal nerve (CN
XII)
Visceral efferent (visceral motor) nuclei:
Nuclei associated with the
parasympathetic nervous system:
 Visceral oculomotor (Edinger –
Westphal) nucleus (CN III)
 Superior salivatory nucleus (facial
nerve, CN VII)
 Inferior salivatory nucleus
(glossopharyngeal nerve, CN IX)
 Dorsal vagal nucleus (CN X)
Nuclei f the branchial arch nerves:
 Trigeminal motor nucleus (CN V)
 Facial nucleus (CN VIII)
 Nucleus ambiguous
(glossopharyngeal nerve, CN IX;
vagus nerve, CN X; accessory
nerve, CN XI, cranial root)
Sensory nuclei: where afferent (sensory) fibers
terminate
Somatic afferent (somatic sensory) and
vesibulocochlear nuclei:
Sensory nuclei associated with the trigeminal nerve (CN
V):
 Mesencephalic nucleus of trigeminal nerve
(special feature: pseudounipolar ganglion cells
(“displaced sensory ganglion”), provide direct
sensory innervation for muscles of mastication)
 Principal (pontine) sensory nucleus of
trigeminal nerve
 Spinal nucleus of trigeminal nerve
Nuclei of the vestibulocochlear nerve (CN VIII):
 Vestibular part:
o Medial vestibular nucleus
o Superior vestibular nucleus
o Lateral vestibular nucleus
o Inferior vestibular nucleus
 Cochlear part:
o Anterior cochlear nucleus
o Posterior cochlear nucleus
Visceral afferent (visceral sensory) nuclei:
 Nucleus of the solitary tract (nuclear complex):
o Superior part:
 Special visceral afferents (taste)
from facial (CN VII),
glossopharyngeal (CN XI), and
vagus (CN X) nerves
o Inferior part:
 General visceral afferents from
glossopharyngeal (CN IX) and vagus
(CN X) nerves
Synopsis of cerebellar classifications
Phylogenetic classification
Anatomical classification

Archicerebellum

Flocculonodular lobe

Paleocerebellum

Anterior lobe of
cerebellum
Portions of the vermis

Functional classification based on the
origin of afferents
 Vestibulocerebellum:
maintenance of equilibrium
 Spinocerebellum: Regulation
of muscle tone
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Neuroanatomy © by Matthias Heyner 2008


Neocerebellum

Median portions of
the posterior lobe
Lateral portions of the
posterior lobe

Pontocerebellum (=
cerebrocerebellum): skilled
movements
Cerebellar Nuclei and the regions of the cortex from which they receive projections
Cerebellar Nucleus
Synonyms
Dentate nucleus
Lateral cerebellar nucleus
Emboliform nucleus
Anterior interpositus nucleus
Globose nuclei
Posterior interpositus nucleus
Fastigial nucleus
Medial cerebellar nucleus
Principal neurons and fiber types in the cerebellar cortex
Region of the cerebellar cortex
that send axons to the nucleus
Lateral part (lateral portions of
the cerebellar hemispheres)
Intermediate part (medial
portions of the cerebellar
hemispheres)
Intermediate part (medial
portions of the cerebellar
hemispheres)
Median part (cerebellar vermis)
Name
Climbing fibers
Definition
Axons of neurons of the inferior olive and its
associated nuclei
Mossy fibers
Axons of neurons of the pontine nuclei, the
spinal cord, and the vestibular nuclei
(pontocerebellar, spinocerebellar, and vestibular
tracts)
Parallel fibers
Axons of the granule cells
Granule cells
Interneurons of the cerebellar cortex
Purkinje cells
The only efferent cells of the cerebellar cortex;
exert an inhibitory effect
Synopsis of the cerebellar peduncles and their tracts
Cerebellar peduncle
Origin**
Site of Termination
and constituent
parts*
Superior cerebellar peduncle: contains mostly efferent tracts from the cerebellar nuclei. Some tracts
cross in the decussation of the superior peduncle, then divide into a descending limb (to the pons)
and an ascending limb (to the midbrain and the thalamus).
Descending parts (e)
Fastigial and globose nuclei
Reticular formation and
vestibular nuclei (projection
is mostly contralateral)
Ascending parts (e)
Dentate nucleus
Red nucleus and thalamus
(both contralateral)
Anterior
Secondary neurons in intermediate gray
Vermis and intermediate
Spinocerebellar tract
matter, lumbosacral spinal cord. Relays
part of anterior lobe of
(a)
proprioception (muscle spindles, tendon
cerebellum (ipsilateral;
receptors, etc) from dorsal root (spinal)
terminates as mossy fibers)
ganglion cells, lower limb and trunk. Fibers
cross locally and then re-cross in the pons to
return to the ipsilateral side.
Middle cerebellar peduncle: contains only afferent tracts.
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Neuroanatomy © by Matthias Heyner 2008
Pontocerebellar fibers
(a)
Basal pontine nuclei. Relay cerebropontine to
pontocerebellar projection (source of 90% of
axons in middle peduncle)
Inferior cerebellar peduncle: contains both afferent and efferent tracts.
Posterior
Posterior thoracic nucleus and thoracic spinal
Spinocerebellar tract
cord. Relays proprioception and cutaneous
(a)
sensation from the lower limb. Contains
large axons with high conduction velocity.
Cuneocerebellar tract
(a)
Olivocerebellar tract
(a)
Vestibulocerebellar
tract (a)
Trigeminocerebellar
fibers (a)
Nucleus cuneatus and external cuneate
nucleus. Relays proprioception (external
cuneate nucleus) and cutaneous sensation
(nucleus cuneatus) from the upper limb, with
fast transmission, functionally corresponding
to the posterior Spinocerebellar tract.
Inferior olivary nuclear complex. Inferior
olive receives numerous inputs from sensory
and motor systems, including a large
contralateral projection from the cerebellum
itself (dentate nucleus, see below)
Semicircular canal (vestibular ganglion) and
vestibular nuclei. Transmits balance and
body position/motion information either
directly (vestibular axons via
vestibulocochlear nerve [CN VIII], ipsilateral)
or via synaptic relay in vestibular nuclei
(bilateral).
Trigeminal sensory nuclei in the brainstem.
Relay proprioception and cutaneous
sensation from the head
Lateral regions of posterior
and anterior lobes of
cerebellum (contralateral;
terminate as mossy fibers;
branches to contralateral
dentate nucleus)
Vermis and nearby anterior
lobe of cerebellum, pyramid
and nearby posterior lobe
of cerebellum. (ipsilateral;
terminates as mossy fibers)
Posterior part of anterior
lobe of cerebellum
(ipsilateral; terminates as
mossy fibers)
Molecular layer of
cerebellar cortex
(contralateral, terminates as
climbing fibers)
Nodule, flocculus, anterior
lobe, and vermis of
cerebellum (bilateral, see
left; terminates as mossy
fibers)
Rostral part of posterior
lobe of cerebellum
(ipsilateral; terminate as
mossy fibers)
Inferior olive (contralateral)
Cerebello-olivary
Dentate nucleus
fibers (e)
*Subentries for constituent parts are classified as efferent (e) or afferent (a).
**In the case of afferents, the type of afferent is listed along with the site of origin
Synopsis of cerebellar classifications and their relationships to motor deficits
Functional classification
Vestibulocerebellum
Spinocerebellum
Phylogenetic
classification
Archicerebellum
Paleocerebellum
Anatomical classification
Deficit symptoms
Flocculonodular lobe

Anterior lobe, parts of
vermis; Posterior lobe,
medial parts





Truncal, stance and
gait ataxia
Vertigo
Nystagmus
Vomiting
Ataxia, chiefly
affecting the lower
limb
Oculomotor
dysfunction
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Neuroanatomy © by Matthias Heyner 2008

Pontocerebellum
(=cerebrocerebellum)
Neocerebellum
Posterior lobe,
hemispheres




Speech disorder
(asynergy of speech
muscles)
Dysmetria and
hypermetria
(positive rebound)
Intention tremor
Nystagmus
Decreased muscle
tone
Synopsis of sensory Pathways
Name of
Sensory quality
Pathway
Spinothalamic tracts
Anterior
 Crude touch
Spinothalamic
tract
Lateral
Spinothalamic
tract

Pain and
temperature
Receptor
Course in the Spinal Central course (above
cord
the Spinal cord)

The perikaryon of
the second neuron
is located in the
posterior horn and
may be up to 15
segments above or
2 segments below
the entry of the
first neuron. Its
axons crossing the
anterior
commissure.
The perikaryon of
the second neuron
is in the substantia
gelatinosa. Its axon
crosses at the same
level in the anterior
commissure.
The axons of the
second neuron (spinal
lemniscus) terminate in
the ventral
posterolateral nucleus
of the thalamus. There
they synapse onto the
third neuron, whose
axons project to the
postcentral gyrus.
VaterPacini
corpuscl
es
Muscle
and
tendon
recepto
rs
The axons of the
first neuron pass to
the nucleus gracilis
in the lower
medulla oblongata
(second neuron)
VaterPacini
The axons of the
first neuron pass to
The axons of the
second neuron cross in
the brainstem and
traverse the medial
lemniscus to the
ventral posterolateral
nucleus of the
thalamus. There they
synapse onto the third
neuron whose axons
project to the
postcentral gyrus
The axons of the
second neuron cross in


Tracts of the posterior funiculus
Fasciculus
 Fine touch

gracilis
 Conscious
proprioception
of lower limb

Fasciculus
cuneatus


Fine touch
Conscious

Hair
follicles
Various
skin
recepto
rs
Mostly
free
nerve
endings
The axons of the
second neuron (spinal
lemniscus) terminate in
the ventral
posterolateral nucleus
of the thalamus. There
they synapse onto the
third neuron, whose
axons project to the
postcentral gyrus
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Neuroanatomy © by Matthias Heyner 2008
Spinocerebellar tracts
Anterior

Spinocerebellar
tract (of
Gowers)
proprioception
of the upper
limb

corpuscl
es
Muscle
and
tendon
recepto
rs
the nucleus
cuneatus in the
lower medulla
oblongata (second
neuron)
the brainstem and
traverse the medial
lemniscus to the
ventral posterolateral
nucleus of the
thalamus. There they
synapse onto the third
neuron whose axons
project to the
postcentral gyrus
Unconscious

crossed and
uncrossed

extero- and
proprioception
to the

cerebellum
Muscle
spindles
Tendon
recepto
rs
Joint
recepto
rs
Skin
recepto
rs
The second neuron
is located in the
dorsal column in
the central part of
the gray matter.
The axons of the
second neuron run
directly to the
cerebellum, both
crossed and
uncrossed without
synapsing with a
third neuron.
The second neuron
is located in the
thoracic nucleus
(Clarke column,
Stilling nucleus) in
the gray matter at
the base of the
posterior horn. The
axons of the
second neuron run
directly to the
cerebellum without
crossing.
The axons of the
second neuron pass
through the superior
cerebellar peduncle to
the vermian part of the
spinocerebellum (no
third neuron

Posterior
Spinocerebellar
tract (of
Flechsig)

Unconscious

uncrossed
extero- and

proprioception
to the
cerebellum


Muscle
spindles
Tendon
recepto
rs
Joint
recepto
rs
Skin
recepto
rs
The axons of the
second neuron pass
through the inferior
cerebellar peduncle to
the vermian part of the
spinocerebellum (no
third nucleus)
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