Thalamus,
Hypothalamus,Epithalamus
Dr. Nimir
Dr. Safaa
 Describe the location of the thalamus .
 List the different parts and nuclei of the thalamus .
 List the afferent input to different nuclei of the






thalamus.
List the efferent output from the different nuclei of the
thalamus.
Describe the structure of hypothalamus, epithalamus ,
and subthalamus.
List the nuclei of the hypothalamus.
List the afferent connections of the hypothalamus.
List the efferent connections of the hypothalamus
List the functions of hypothalamus.
 The thalamus is an egg-







shaped gray matter
situated rostral (superior)
to brainstem, one in each
cerebral hemisphere.
Between them is third
ventricle.
They may connect with
interthalamic connection
(adhesion).
It is an important relay and
integrative station for
information passing to:
All areas of cerebral cortex.
Basal ganglia.
Hypothalamus.
Brainstem.
 Subdivisions of the
thalamus:
 Internal medullary
lamina is a Y shape sheet
of white matter dividing
the thalamus into 3
parts:
 Anterior part that
contains anterior
thalamic nuclei which
receive
mammillothalamic tract
& also receive reciprocal
connections with the
cingulate gyrus and
hypothalamus.
 Its function is concerned
with emotion & recent
memory.
 Medial part that contains
dorsomedial nucleus &
several smaller nuclei.
Dorsomedial nucleus has
two-way connections with
prefrontal cortex,
hypothalamic nuclei &
thalamic nuclei.
 Its function is integration
of somatic, visceral, and
olfactory informations,
and relating them to
one's emotional feelings
and subjective states.
 Lateral Part which is
subdivided into dorsal
tier & ventral tier.
 Dorsal tier includes
lateral dorsal nucleus,
lateral posterior nucleus,
and pulvinar. They are
interconnected with
other thalamic nuclei ,
parietal lobe, cingulate
gyrus, occipital and
temporal lobes.
 Their function is not well
known & mostly
associated with
emotions, sensory
integration & vision.
 Ventral tier consists of the




following nuclei in a
craniocaudal sequence:
Ventral anterior nucleus
which is connected to
reticular formation,
substantia nigra, corpus
striatum, premotor cortex
and thalamic nuclei.
It influences motor
activity.
Ventral lateral nucleus
has similar connections
to that of ventral anterior
nucleus plus input from
cerebellum & red nucleus.
It influences motor
activity.
 Ventral posterior
nucleus is subdivided
into ventral
posteromedial
nucleus and ventral
posterolateral
nucleus.
 Ventral
posteromedial
receives ascending
trigeminal and
gustatory pathways.
 Ventral posterolateral
receives the
important ascending
sensory tracts, the
medial and spinal
lemnisci.
 Both nuclei relay
common sensations
to consciousness.
 Other Nuclei of the




Thalamus:
Intralaminar nuclei
are within the
internal medullary
lamina & they
influence the levels of
consciousness and
alertness.
Midline nuclei
adjacent to the third
ventricle.
Reticular nucleus is
between external
medullary & internal
capsule.
It regulates thalamus
by cerebral cortex.
 Medial geniculate body
forms part of the auditory
pathway.
 Lateral geniculate body
forms part of the visual
pathway.
 Hypothalamus:
 Is the part of
diencephalon that
extends from the region
of the optic chiasma to
mammillary bodies.
 When observed from
below it is related to
optic chiasma, tuber
cinereum,
infundibulum and
mammillary bodies.
 Hypothalamic nuclei
are divided into medial
and lateral zones.
 Medial zone include from








anterior to posterior:
Part of the preoptic
nucleus.
Anterior nucleus.
Part of suprachiasmatic
nucleus.
Paraventricular nucleus.
Dorsomedial nucleus.
Ventromedial nucleus.
Infundibular (arcuate)
nucleus.
Posterior nucleus.
 Lateral zone include






from anterior to
posterior:
Part of the preoptic
nucleus.
Part of
suprachiasmatic
nucleus.
Supraoptic nucleus.
Lateral nucleus.
Tuberomammillary
nucleus.
Lateral tuberal
nuclei.
 Hypothalamus receives














information from the body
through:
Nervous connections.
Bloodstream.
Cerebrospinal fluid.
Hypothalamic nuclei respond
and exert their control via the
same routes.
Afferents:
Somatic and visceral afferents.
Visual afferents.
Olfaction.
Auditory.
Corticohypothalamic from
frontal lobe.
Hippocampohypothalamic
Amygdalohypothalamic.
Thalamohypothalamic.
Tegmental.
 Efferent:
 Descending fibers to
the brainstem and
spinal cord.
 Mammillothalamic
tract.
 Mammillotegmental
tract.
 Multiple pathways to
the limbic system.
Functions of the Main Hypothalamic Nuclei
Hypothalamic Nucleus
Presumed Function
Supraoptic nucleus
Synthesizes vasopressin (antidiuretic hormone)
Paraventricular nucleus
Synthesizes oxytocin
Preoptic and anterior nuclei
Control parasympathetic system
Posterior and lateral nuclei
Control sympathetic system
Anterior hypothalamic nuclei
Regulate temperature (response to heat)
Posterior hypothalamic nuclei
Regulate temperature (response to cold)
Lateral hypothalamic nuclei
Initiate eating and increase food intake (hunger
center)
Medial hypothalamic nuclei
Inhibit eating and reduce food intake (satiety center)
Lateral hypothalamic nuclei
Increase water intake (thirst center)
Suprachiasmatic nucleus
Controls circadian rhythms
 The epithalamus consists of









habenular nuclei and their
connections and pineal gland.
Habenular nuclei are medial
to the posterior surface of the
thalamus.
Receive afferents from:
Amygdaloid nucleus through
the stria medullaris thalami
( some cross to form
habenular commissure).
Hippocampal formation
through the fornix.
Send efferents to:
Interpeduncular nucleus.
Tectum of the midbrain.
Thalamus.
Reticular formation of the
midbrain.
 Pineal gland is behind
thalami & above superior
colliculi.
 Its stalk base contains
habenular commissure
above & posterior
commissure below.
 Receives afferents from
superior cervical
sympathetic ganglia.
 Its secretions(melatonin)
reach target organs
(pituitary, pancreas,
parathyroids, adrenals
and gonads) via the
bloodstream or through
the cerebrospinal fluid.