Download Brain days-Part III

Kaan Yücel M.D.,Ph.D.
Learning Objectives
Explain the components of the diencephalon
Explain the anatomical features of the structures in diencephalon
1. Diencephalon
Prosencephalon
[Forebrain]
1. Telencephalon
2. Diencephalon
2. Diencephalon is composed of…
(1)
(2)
(3)
(4)
thalamus
subthalamus [-sub: 'inferior to”]
epithalamus [-epi: “superior to”]
hypothalamus [-hypo: “under” ]
2. Diencephalon extends...
posteriorly
where 3rd ventricle becomes continuous with the cerebral aqueduct
anteriorly
interventricular foramina
A midline structure with symmetrical right and left halves
2. Diencephalon’s inferior surface
• Only area exposed to the surface in the intact brain.
• Formed by hypothalamic and other structures, which include, from
anterior to posterior:
o optic chiasma
o infundibulum
with the tuber cinereum [x]
o mammillary bodies
[x]
2. Diencephalon’s superior surface
•
Concealed by the fornix.
•
The actual superior wall of the diencephalon is formed by roof of
the third ventricle.
A pair of vascular processes, choroid plexuses of the third ventricle,
project downward from the midline into the cavity of the third
ventricle and CSF is produced here.
•
2. Diencephalon’s lateral surface
Bounded by the internal capsule
oconsists of nerve fibers
oconnect the cerebral cortex with parts of the brainstem and spinal
cord. MRI of the brain, T1-weighted axial cut
1. Insula
2. Internal capsule
3.Caudate nucleus
4. Putamen
5. Internal capsule
Posterior limb
6. Splenium, corpus callosum
7.Thalamus
2. Diencephalon’s medial surface
a.k.a. Lateral wall of the third ventricle
Superior part by medial surface of thalamus
hypothalamic sulcus
Inferior party by hypothalamus
stria medullaris thalami
•Afferent fibers to the
habenular nucleus
•Forms a ridge along the
superior margin of the
medial surface of the
diencephalon
3. Thalamus
L. thalamus "inner chamber," from Gk. thalamos
"inner chamber, bedroom"
Large ovoid mass of gray
matter that forms the major
part of the diencephalon.
On each side of the third
ventricle.
3. Thalamus
The superior surface of the thalamus is
covered medially by the tela choroidea and
the fornix
The inferior surface is continuous with the
tegmentum of the midbrain.
3. Thalamus
The medial surface of the thalamus forms
the superior part of the lateral wall of the
third ventricle
Usually connected to the opposite thalamus
by a band of gray matter,
interthalamic connection
(interthalamic adhesion- adhesio
interthalamica- massa interrmedia)
Found in 70-80% of humans
Axial T2-weighted MR image
C = caudate nucleus
G = globus pallidus
L = lentiform nucleus (G+P)
P = putamen
T = thalamus
 Important station that receives the main sensory tracts (except the
olfactory pathway).
 A station where much of the information is integrated and relayed
to the cerebral cortex and many other subcortical regions.
 A key role in the integration of visceral and somatic functions.
3. Thalamus
Anterior thalamic nuclei, which receive the
mammilothalamic tract from the mammillary
nuclei.
Associated with of that of the limbic system and is
concerned with emotional tone and the
mechanisms of recent memory.
3. Thalamus
Medial part of the thalamus large dorsomedial nucleus and several
smaller nuclei.
2 connections with the whole prefrontal cortex and hypothalamic
nuclei.
Responsible for
integration of a large
variety of sensory
information
relation of this
information to one’s
emotions
3. Thalamus
Stria terminalis: Runs @ lateral margin of thalamus
From amygala to hypothalamus
Major output of amygdala
4. Hypothalamus
from the region of the
optic chiasma to the
caudal border of the
mammillary bodies
4. Hypothalamus
four distinct groups in the rostral-caudal plane of the third ventricle:
1. preoptic (above and in front of the optic chiasm - telencephalic
extension of the basal forebrain, but functionally diencephalonic)
2. chiasmatic (above and around the optic chiasm)
3. tuberal (above and around the "tuber cinereum", i.e. pituitary stalk)
4. posterior region which includes the mammillary bodies.
4. Hypothalamus
When observed from below, the hypothalamus is seen to be related to
the following structures, from anterior to posterior:
(1) optic chiasma
(2) tuber cinereum & infundibulum
(3) mammillary bodies
5. Subthalamus
Inferior to thalamus
Between thalamus-midbrain
Anteriomedially- hypothalamus
Important connections with the
striatum
Fxn: Control of muscle activity
Adhesio
interthalamica
Septum pellicidum
Pineal gland
Anterior
commissure
Posterior
commissure
Corpora
quadrigemina
AC
Thalamus
Optic
chiasm
Hypothalamus Mamillary body
Cerebral aqueduct
Pituitary gland
6. Pituitary gland
Hormone
Stimulated by the hypothalamic
Does
hormone
Anterior pituitary gland (Adenohypoysis)
Growth Hormone (GH)
Growth Hormone-Releasing Hormone
Growing
(GHRH)
Thyroid-stimulating
Thyrotropin-Releasing Hormone (TRH)
Metabolism of the body
Corticotropin-Releasing Hormone (CRH)
Production and release of corticosteroids from the
hormone (TSH)
Adrenocorticotropic
hormone (ACTH)
adrenal glands
Prolactin (PRL)
Long list of chemical substances,
Stimulation of milk production in breasts
Luteinizing hormone (LH)
inhibited by dopamine
Gonadotropin-Releasing Hormone
(GnRH)
Triggers ovulation
Gonadotropin-Releasing Hormone
(GnRH)
Regulates the development, growth, pubertal
Follicle-stimulating
hormone (FSH)
ICHS production of testosterone
maturation, and reproductive processes of the body
Posterior pituitary gland (Neurohypoysis)
Oxytocin
Secreted from the hypothalamus and
Distension of the cervix and uterus during labor,
carried to the pituitary gland
facilitating birth, and after stimulation of the nipples,
facilitating breastfeeding.
Antidiuretic hormone
Secreted from the hypothalamus and
Increases water absorption in the the kidney
7. Tuber Cinereum
Interthalamic adhesion
8. Mammillary bodies
Two small hemispherical bodies situated
side by side posterior to the tuber
cinereum.
Possess a central core of gray matter
invested by a capsule of myelinated nerve
fibers.
Korsakoff’s Syndrome
Wernicle-Korsakoff Syndrome
Copenhaver BR, Rabin LA, Saykin AJ,
Roth RM, Wishart HA, Flashman LA,
Santulli RB, McHugh TL, Mamourian
AC. The fornix and mammillary bodies
in older adults with Alzheimer's
disease, mild cognitive impairment,
and cognitive complaints: a volumetric
MRI study. Psychiatry Res. 2006 Oct
30;147(2-3):93-103.
Yoneoka Y, Takeda N, Inoue A, Ibuchi Y,
Kumagai T, Sugai T, Takeda K, Ueda K. Acute
Korsakoff syndrome following
mammillothalamic tract infarction.
AJNR Am J Neuroradiol. 2004;25(6):964-968.
Vann SD. Re-evaluating the role of the
mammillary bodies in memory.
Neuropsychologia. 2010;48(8):2316-2327.
Septum pellicidum
Fornix
Thalamus
Hypothalamus
AC
PC
Optic
chiasma
Pituitary
gland
Mammillary bodies
Lamina terminalis
Fornix
Interthalamic adhesion
Thalamus
Habenula
AC
Hypothalamus
Optic chiasm
Infundibulum
Pituitary gland
Pineal gland
Tuber cinerum
PC
8. Epithalamus
Pineal gland+habenular nucleus+stria
medullaris thalami
Pineal gland:
Inhibition of hormones
Circadian rhythm day & nigh time
Melatonin
Habenula:
potential importance of
the lateral habenular nucleus
in regulating the
dopamine reward signal
Haber SN, Knutson B. The reward
circuit: linking primate anatomy
and human imaging.
Neuropsychopharmacology.
2010;35(1):4-26.
9. Third ventricle
Between two thalami
Lateral Ventricle
Interventricular foramina
(foramina of Monro)
4th Ventricle
Cerebral aqueduct (of Sylvius)
9. Third ventricle
Anterior wall
Lamina terminalis
AC
Posterior wall
Cerebral aqueduct
Superior to PC pineal recess
Superior to pineal recess
habenular commissure
Lateral wall
Sup:Medial surface of
thalamus
Inf: Hypothalamus
Superiorly limited by
stria medullaris thalami.
Anterior commissure (AC)
Connecting temporal lobes
Posterior commissure (PC)
Pupillary eye reflex