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1. Department of Normal Anatomy
Lecture theme
Diencephalon, third ventricle: structure and functions.
Mesencephalon, cerebral aqueduct: structure and
functions.
• Doctor of Medical Sciences, Professor
Dyusembaeva A.T.

3. DIENCEPHALON (intermediate brain)
Intermediate brain, diencephalon includes: the thalamic region, hypothalamus and
III ventricle.
I. Thalamic region. By the thalamic region include: thalamus, metatalamus and
epithalamus.
1. The thalamus or optic tubercle, thalamus - a pair of gray matter, egg-shaped, has
in front - anterior tubercle, tuberculum anterius, and a pillow behind, pulvinar.
Surfaces:
A. medial- facing the III ventricle, in the middle connected by intertalamic
commissure - adhesio interthalamica, separated from the upper surface by the
brain strip, stria medullaris;
B. upper - forms the bottom of the central part of the lateral ventricle, is separated
from the caudate nucleus by the border furrow, sulcus terminalis, in which the
border strip passes, stria terminalis;
C. lateral - bordered by the inner capsule;
D. lower - bordered by midbrain.
The thalamus is made up of gray matter, which contains up to 40 nuclei. The main
groups of thalamic nuclei are anterior, medial, lateral and posterior. The processes
of neurons of all types of sensitivity come into contact with the nerve cells of the
thalamus. The thalamus is the subcortical center of almost all types of sensitivity,
the subcortical center of vision, the sensitive center of the extrapyramidal system.

7. Thalamus

9. Metatalamus, metathalamus
The metathalamus consists of the
lateral and medial geniculate body.
The lateral geniculate body is
located lateral to the pulvinar and
can be found along the optic tract.
The medial geniculate body is
located under the pulvinar medially
from the lateral geniculate body.
The lateral geniculate body is the
subcortical center of vision. The
medial geniculate body is the
subcortical center of hearing.

12. Epithalamus, epithalamus
The epithalamus includes the
pineal gland, which the
habenulae connects to the
thalamus.
Habenulae are connected to
thalamus using habenulae
triangles.
Between the habenulae in
front there is a comissurae of
the habenula.
There is an epithalamic
comissurae under the
habenular comiisura, between
which there is a pineal recess.

14. Hypothalamus, hypothalamus
Hypothalamus forms the lower sections of the diencephalon. The
hypothalamus includes:
1. The optic chiasma, chiasma opticum, which passes into the optic tract,
tractus opticus;
2. Tuber cinereum, the tip of which is extended into a funnel,
infundibulum, on which the pituitary gland is located. Tuber cinereum is
the highest vegetative center;
3. Mastoids body, corpora mamillaria - two white globular formations,
inside of which is gray matter. Mastoids body are the subcortical olfactory
centers;
4. The posterior hypothalamic region, regio hypothalamica - a small area
of ​​the medulla, located under the thalamus, in it lies the subtalamic
nucleus (Lyuis,s body), refers to the extrapyramidal and vegetative
systems. In the hypothalamus laid more than 30 nuclei. The nerve cells of
the hypothalamic nucleus produce neurosecretes, which along the
processes of these cells enters the pituitary gland, enhancing or inhibiting
its secretion, forming the whole hypothalamic-pituitary system, regulating
the activity of other endocrine glands.

18. The third ventricle, ventriculus tertius
The third ventricle, ventriculus tertius, is the cavity of the
diencephalon. Walls:
A. lateral walls - formed by the thalamus;
B. The lower wall is formed by the hypothalamus, there are two
deepening on it - a funnel recess and a optic recess, recessus
infundibuli et opticus.
C. The front wall is formed by the terminal plate, columna and
anterior commissure. There is an interventricular foramen,
foramina interventricularia, between the column of the fornix
and the thalamus, which connects with the lateral ventricles;
E. The upper wall is formed by the choroid, tela choroidea.
D. the back wall is formed by commissure of the habenula and
posterior commissure of the brain, between which there is a
pineal recess, recessus pinealis. Under the posterior cerebral
commissure there is a hole leading to the aqueduct of the brain.

21. MIDBRAIN, MESENCEPHALON
The midbrain, the mesencephalon, consists of a roof, legs of the brain and
the aqueduct.
1. The midbrain roof, tectum mesencephali, consists of 4 hillocks - upper
and lower hillocks. The upper two hillocks, colliculi superiores are the
subcortical centers of vision, the lower hillocks of colliculi inferiores are the
subcortical centers of hearing. From these subcortical centers there is a
path, tractus tecto-spinalis, which intersects with the path of the opposite
side, forming a dorsal intersection, decussationes tegmenti dorsales. This
path is responsible for auditory and visual reflexes.
Hillocks continue into the handles. The handle of the upper hillock,
brachium colliculi superioris, goes to the lateral geniculate body, corpus
geniculatum laterale. The handle of the lower hillock, brachium colliculi
inferioris goes to the medial geniculate body, corpus geniculatum mediale.
2. Brain legs, pedunculi cerebri - contain all pathways to the endbrain.
3. The cerebral aqueduct (of Sylvius), aqueductus cerebri in the form of a
narrow channel (1.5 cm) connects the III ventricle with the IV ventricle.

23. MESENCEPHALON
1- tectum;
2- pedunculi cerebri;
3- aqueductus cerebri;
4- substantia nigra;
5- tegmentum;
6- formatio reticularis;
7- nucleus oculomotorius;
8- nucleus accessorius;
9- nucleus tractus mesencephalici nervi trigemeni;
10- tractus tectospinalis;
11- nucleus nervi trochlearis;
12- decussation of Meynert;
13- lemniscus medialis;
14-lemniscus lateralis;
15- nucleus ruber;
16- decussation of Forel (tractus rubrospinalis);
17- tractus occipitotemporopontinus;
18- tractus frontopontinus;
19- tractus corticospinalis;
20- tractus corticonuclearis.

25. The internal structure of the midbrain
The internal structure of the midbrain: in the transverse section, the midbrain is
divided into a plate of the roof, lamina tecti, cover, tegmentum and base of the
crus of the brain, basis pedunculi cerebralis. The aqueduct of the brain is
surrounded by a central gray matter belonging to the autonomic nervous system.
At the level of the upper hillock there are 2 nuclei of the oculomotor nerve, n.
oculomotorius (III pair) - motor core and vegetative accessory nucleus, nucleus
accessorius (Yakubovich's nucleus). The motor nucleus innervates the muscles of
the eye, the autonomic nucleus, the ciliary muscle and the muscle narrowing the
pupil. At the level of the lower hillock, the motor core of the block nerve is laid, n.
trochlearis (IV pair). The boundary between the tegmentum and the base of the
legs of the brain is the black substance, the substantia nigra (color due to the
pigment melanin). Black matter refers to the extrapyramidal system. There is a red
nucleus in the cover, the nucleus ruber, from it begins the red-spinal cord path,
the tractus rubrospinalis, which intersects with the opposite side, forming the
ventral crossing of the cover, decussationes tegmenti ventrales and goes to the
front horns of the spinal cord. The red nucleus is an important coordination center
of the extrapyramidal system and is connected with its parts (cerebellum,
striopallidar system) -affecting the entire skeletal muscles, regulating instinctive
automatic movements. In the cover there is the Darkeshevich's nucleus from which
the medial longitudinal fascicle comes, fasciculus longitudinalis medialis,
connecting the nuclei of the optic nerves (III, IV, VI pairs) with each other

35. Questions for lesson preparation:
• 1. The mesencephalon, its parts
• 2. The internal structure of the mesencephalon
• 3. Cerebral aqueduct, its functional significance
• 4. Parts of the diencephalon
• 5. Thalamus, its surfaces, topography, internal
structure, functional significance
• 6. Parts of the epithalamia region
• 7. Metathalamus, functional value
• 8. Hypothalamus, dividing it into parts
• 9. III ventricle, its walls, connections
• 10. Age features of the mesencephalon and
diencephalon