corpus callosum, fornix, anterior commissure, basal nuclei, internal capsule, anatomy of the olfactory brain, lateral ventricle human nervous system anatomy and medical terminology histology Azerbaijan medical university (AMU)

1. Anatomy and medical terminology
Topics: corpus callosum, fornix, anterior
commissure, basal nuclei, internal capsule,
anatomy of the olfactory brain, lateral ventricle
Written by: Roya Basser
Faculty: dentistry
Azerbaijan mdical university (AMU)
2020-2021

2. Elements
Hemisphere
Matters of brain
Commissures
Corpus callosum
fornix
Anterior commissure
Olfactory part
Basal ganglia and internal capsule
Lateral ventricle

3. Hemisphere
In general brain is made up of 2
hemispheres: right and left
which are separated from each
other by a deep longitudinal
fissure.
It is necessary to point out that
we can classify each hemisphere
according to different variants,
such as function, matters and so
on.

4. Hemisphere classify (FUNCTION)-over view
HEMISPHERE
FUNCTION
LOBES
TEMPORAL OCCIPITAL FRONT
AL PAREITAL

5. Hemisphere classify –matters and spaces -over view
Hemisphere
Gray matter
Cortex
Basal ganglia
Caudate nucleus
Lentiform
nucleus
White matter
Association
fibers
Projection fibers
Commissure
fiber
Ventricles
Lateral ventricle
Third ventricle
Fourth ventricle
Note:
Here Is a general view of
hemispheres.

6. White matter
White
matter
Association
fibers
Short: connect adjacent
neocortical fibers in the same
hemisphere.
Long; connect distant
neocortical fibers.
Projection
fibers
Ascending (corticopetal)
Afferent
Descending(corticofugal)
Efferent
Commissur
al fibers
Carpus callosum
Fornix
Anterior commissure
Posterior commissure

7. Commissures
• Definition: The right and left cerebral hemispheres are
connected by three (in some sources it is 4) tracts of
nerve fibers or axons, which are collectively referred to
as commissures.
• Types of commissures:
• As I mentioned before, there are 3 types of commissures
in the brain:
• Carpus callosum
• The largest one
• Fornix
• Anterior commissure
• Posterior commissure
Note:
Here the commissures of brain are
demonstrated by colors.

8. Corpus callosum
• Function :
• Corpus callosum is the largest commissure In the
brain which connects 2 cerebral hemispheres (right
and left) to each other.
• It transfers these 3 kinds of information:
1. Motor information
2. Sensory information
3. Cognitive information
• Size:
• It is a bout 10 cm.
• Shape:
• Almost C-shaped
Note:
Here is the general location of
corpus callosum

9. Corpus callosum
Location
• It is located in the depth of longitudinal
fissure of brain.
• Also we can say that is located
underneath the center of cerebrum.
• It is 3.0 cm behind the anterior end of
the hemispheres and 6.0 cm in front of
the posterior end of the hemisphere.
Also It surrounds the horns of the
lateral ventricles from outside and
involve in the formation of third
ventricle.
Note:
Here are 3 views of corpus callosum that show the
general location of it in brain.

10. Corpus callosum
• It is made up of 200 millions of fibers.
• The matter of brain which involves in the
formation of carpus callosum is white matter
that is mad up of dense myelinated fibers.
• The corpus callosum gets its name from the
Latin language (“tough body”).
• the different parts of the corpus callosum
connect similar areas of each hemisphere
except for temporal lobe.
Temporal lobes of 2 hemispheres are connected
to each other by anterior commissure.

11. Corpus callosum-parts in horizontal cut
Parts
of
corpus
callosum
rostrum
Genu
Trunk
Body
Isthmus
Splenium
Note:
Here are 2 simple picture of corpus callosum to identify the parts of it.

12. Corpus callosum
• 1-genu and rostrum:
• Genu is the most anterior part of corpus
callosum which is curved ventrally and its fibers
connect frontal lobes of both hemispheres.
• The curved fibers from genu to frontal lobe is
called forceps minor.
• The genu bends inferior and backward and forms
rostrum.
• The rostrum continues to the lamina terminalis
which makes up the anterior wall of 3rd
ventricle. It connects the orbital surfaces of the
frontal lobes.
• Genu in Latin means knee and the rostrum is
named for its resemblance to the birds beak.
Note:
Here is a simple model that shows the
genu.

13. Corpus callosum
2. Body or trunk:
• The body forms the long central section
and it is located between the genu and
splenium.
• The largest part
• Has 2 aspects: superior and inferior
• its fibers pass through the corona radiata
to reach the surface of the hemispheres.
• Has 3 parts:
• Anterior mid body
• Middle midbody
• Posterior midbody
• It connects 2 partial lobes.

14. Corpus callosum
3. Isthmus and splenium
• Isthmus is a part between the splenium
and body which is a little thinner then
other parts.
• Splenium is the posterior part that is
thick.
• Splenium projecting fibers are called
forceps major that connects 2 occipital
lobes to each other.
• Also selenium is towards the cerebellum.

15. Corpus callosum-fibers
relations Forceps minor:
Curved tract fibers from genu that connect
the lateral and medial surface of frontal
lobe of each hemisphere.
Tapetum :
White matter fibers projecting from the body and
fibers from the splenium not included in the forceps
major are known as the tapetum.
Callosal fibers that form roof of the lateral ventricle
constitute the tapetum.
Forceps major:
The splenium and the radiations that
connect the occipital lobes constitute the
forceps occipitalis (forceps major).
Note:
Here are the fibers of corpus
callosum.

16. Corpus callosum-neural fibers
Thinner axons in the genu connect the
prefrontal cortex between the two halves of
the brain; these fibers arise from a fork-like
bundle of fibers from the tapetum, the
forceps minor. Thicker axons in the trunk of
the corpus callosum, interconnect areas of the
motor cortex, with proportionately more of
the corpus callosum dedicated to
supplementary motor regions including Broca's
area. The splenium, communicates
somatosensory information between the two
halves of the parietal lobe and the visual
cortex at the occipital lobe, these are the
fibers of the forceps major

17. Corpus callosum-surrounding parts
1) Interhemispheric fissure: in the superior part of
carpus callosum.
2) callosal sulcus: separates the corpus callosum
from the cingulate gyrus.
3) Cingulate gyrus: in the superior and lateral
part of the corpus callosum.
4) Fornix and septum plasidus :The anterior part
of the corpus callosum (rostrum, genu, body) is
attached inferiorly to the fornix by the septum
pellucidum.
5) Lateral ventricle: Posteriorly, the body of
lateral ventricle reaches the splenium of the
corpus callosum also its roof formed by the
trunk of the corpus callosum.

18. Fornix
• It is the second part of commissures and is a part
of limbic system.
• Function:
• It connects temporal lobe to the
hypothalamus.in more details it connects
hippocampus to the mammillary body and septal
nuclei of thalamus. also it Is the major output of
hippocampus.
• The primary role of the fornix is to transmit the
information from the hippocampus to the
mammillary bodies and to the anterior nuclei of
thalamus.
• The specific role of the fornix is not clear yet
but some researches prove that it involves in
memory.

19. Fornix-location
It is a white matter structure that arches
over the lateral ventricle.
ventricular system
The fornix originates in the hippocampus,
where it emerges from a collection of
fibers called the fimbria. It then stretches
up and around the thalamus toward the
front of the brain. When it reaches a tract
called the anterior commissure, it branches
downward.
Between fornix and corpus callosum there
is a septum which is called septum
plasidum and it separates 2 lateral
ventricles from each other.

20. Fornix
Parts
Alveous
Fimbria
Crura(crus)
Posterior pillari
Body
Columns
Anterior pillary

21. Fornix- parts
1-alveous and fimbria:
• Alveus: The fornix begins with myelinated
axons exiting the hippocampus to form the
alveus along the ventricular surface of the
hippocampus (these fibers are found medially
to the floor of the temporal horn of lateral
ventricle.)
• Fimbria: As the axons come together medially,
they form a bundle referred to as the fimbria
of the fornix.

22. Fornix- parts
2-crus (plural crura):
• Crura in general has 2 branches:
Crus: The main bulk of fimbriae continues on each
side of the cerebral hemisphere to form the crus of
the fornix.
The two crura (posterior pillars), one for each
hemisphere, arch anterosuperiorly under the
splenium of the corpus callosum.
Commissure of hippocampus : connection between 2
crura is called commissure of hippocampus.
Crura
Commissure of
hippocampus

23. Fornix-body
• Both crura continue anteriorly and
merge in the midline to form the
body of the fornix. The body of the
fornix arches over the thalamus and
under the septum pellucidum, which
connects it to the corpus callosum.
The lower edge of the septum
pellucidum (the membrane that
separates the lateral ventricles) is
attached to the upper face of the
fornix body.

24. Fornix-columns
• The body of the fornix extends anteriorly and
bifurcates into the right and left halves called the
columns of the fornix. Each column turns downwards
just in front of the interventricular foramen of Monro
and passes through the hypothalamus to reach the
mammillary body. The columns of the fornix divide at
the level of the anterior commissure and form the
pericommissural and postcommissural fornix. The
columns (anterior pillars) of the fornix arch downward
in front of the interventricular foramina and behind
the anterior commissure, and each descends through
the grey matter in the lateral wall of the third
ventricle to the base of the brain, where it ends in the
mammillary bodies.

25. Fornix-columns
Columns
At the level of
anterior
commissure
Pericommissural descend in front of the
anterior commissure
relay onto: septal nuclei
ventral striatum
cingulate gyrus
Postcommissural behind the anterior
commissure
relay onto:
mammillary bodies.
the anterior nuclei of the thalamus
dorsal fornix

26. Fornix-connections
connections Hippocampal
commissure
interconnect the
contralateral hippocampi of
the two cerebral
hemispheres.
Post commissural originate from the subiculum
of the hippocampus.
1 indirect subiculothalamic
pathway
2direct subiculothalamic
pathway
Pericommissural connect the hippocampus to
the septal nuclei, preoptic
nuclei, ventral striatum,
orbital cortex and anterior
cingulate cortex
Dorsal
commissure
Fibers from the dorsal fornix
reach the splenial gyrus and
the gyrus cingul

27. Anterior commissure
• Function:
• The anterior commissure is a bundle of axons
that crosses the midline in the lamina
terminalis.
• It is white matter.
• The anterior commissure plays a key role in pain
sensation, more specifically sharp, acute pain.
• It provides for additional communication
between the temporal lobes.
• The anterior commissure includes fibers that
connect the middle and inferior temporal gyri of
the two sides.

28. Anterior commissure-location
• The anterior commissure is located in the
anterior wall of the third ventricle at the
upper end of the lamina terminalis.
• it runs across the midline in front of the
anterior columns of the fornix, above the
basal forebrain and beneath the medial and
ventral aspect of the anterior limb of the
internal capsule.
• The anterior commissure is divided into an
anterior and a posterior bundle when traced
laterally, and the posterior half passes
underneath the lentiform nucleus of the basal
ganglia

29. Anterior commissure-parts
Ant commissure
Ant part It connects 2 anterior
olfactory nuclei
Post part
Connects symmetrical
parts of the temporal
lobe

30. Ventricular system of brain
• Definition :
• The comminuting system of
cavities in the brain.
• Within each ventricle is a region of
choroid plexus which produces the
circulating cerebrospinal fluid
(CSF).
• They’re filled with cerebrospinal
fluid (CSF)
• The ventricular system is derived
from the inner lumen of the
developing neural tube.
•
Note:
General position of ventricular system in brain

31. Ventricular system-parts
Lateral
ventricles
Third ventricle
Ventricular
system Cerebral
aqueduct
Fourth ventricle
A cast of the ventricular system of the brain. (A)
Left lateral ventricle. (B) Interventricular
foramen.
(C) Third ventricle. (D) Cerebral aqueduct. (E)
Fourth ventricle.
A
B
C
D
E

32. Ventricular system-lateral ventricle
• The lateral ventricles are the largest in the
series of four interconnecting fluid-filled
cavities within the brain.
• C-shaped
• Each lateral ventricle is a cavity located deep
within the cerebrum and is inferior to the
carpus callosum.
• There are 2 in general.
• Largest ventricles.
• Inferior and lateral to the corpus callosum are
• two large, fluid-filled cavities that represent
the beginning of the ventricular system.
Note:
General views of lateral ventricle in the brain

33. lateral ventricle
Lateral
ventricle
Horns
Inferior
(Temporal)
Anterior(frontal)
Posterior(occipital)
Body
Atrium

34. Lateral ventricle-body
• Body :
• The central part of the lateral
ventricle is elongated
anteroposteriorly. Anteriorly, it
becomes continuous with the
anterior horn at the level of the
interventricular foramen.
Posteriorly, the body reaches the
splenium of the corpus callosum.

35. Lateral ventricle-body walls
Walls of body
Roof
Roof is formed by carpus
callosum.
Medial wall
Septum pellucidum
Body of fornix
Floor
Medially
Superior surface of
thalamus
Laterally
Caudate nucleus

36. Lateral ventricle-Atrium
Atrium is a part that:
I. Anterior horn
II. Central part
III. Inferior horn
become together and make
this part.

37. Lateral ventricle-anterior horn
Anterior horn
• The frontal horn of the ventricle
extends forward from the region of
the interventricular foramen. The
corpus callosum continues as the
roof, and the genu of the corpus
callosum limits the frontal horn in
front. The septum pellucidum
bridges the interval between the
fornix and corpus callosum in the
midline, separating the frontal horns
of the two lateral ventricles.

38. Lateral ventricle-anterior horn walls
walls
Roof
Its roof is formed by
the most anterior
part of the trunk of
the corpus callosum
Floor
floor is formed by
the head of the
caudate nucleus
Medial
The medial wall is
formed by the
septum pellucidum.

39. Lateral ventricle-posterior horn
• The posterior (occipital) horn of the lateral
ventricle extends posteromedially into the
occipital lobe which is of variable length, is
surrounded by cerebral white matter.
• like other parts of the lateral ventricle it has a
roof, lateral wall and a medial wall.
• Projecting into the occipital lobe is the
posterior (occipital) horn so it is within the
occipital lobes.
• It is the shortest of the three.
• It may even be absent.

40. Lateral ventricle-posterior horn walls
walls
Lateral
Roof of it is
formed by
tapetum
medial
calcar avis
Superior and
inferior elevations
Corresponds to
the calcarine
sulcus.
Bulb
Superior to the
calcar avis
formed by fibers
of the forceps
major

41. Lateral ventricle-inferior horn
• The inferior (temporal) horn is the largest component of
the lateral ventricle. It begins at the posterior end of
the central region, and runs anteroinferiorly into the
temporal lobe.
• The situation of it is in temporal lobe.
• It extends from the meting part of the central part and
the posterior horn to 2.5 cm behind the temporal lobe.
• Largest and longest part.
• A triangular area, called the collateral trigone, is found
in the floor of the ventricle where the occipital and
temporal horns diverge from the central part of the
ventricle
• The collateral sulcus on the external surface of the
hemisphere is located immediately below the trigone
and may produce a collateral

42. Lateral ventricle-inferior horn walls
walls
roof
Lateral part tapetum
Medial part
Tail of caudate
nucleus
Stria
terminalis
floor
Hippocampus
Collateral
eminence
Choroid plexus

43. Lateral ventricle

44. Lateral ventricle-connections and separations
Connection
2 lateral
ventricles
connecting
channels
T
o the third
ventricle
Foramen monro
Separation
of
2
ventricles
Septum
pellucidum

45. Septum pellucidum
• The septum pellucidum is located in the
septal area in the midline of the brain
between the two cerebral hemispheres
and runs directly down in the midline.
• the septum pellucidum acts as a partition
between a portion of the lateral
ventricles, forming part of the walls of the
anterior region of the lateral ventricles.
• It is a thin, triangular, vertical double
membrane separating the anterior horns
of the left and right lateral ventricles of
the brain. It runs as a sheet from the
corpus callosum down to the fornix.

46. Choroid plexus and choroid fissure
• The choroid plexus of each lateral ventricle is
formed by an invagination of vascular pia mater
(the tela choroidea) on the medial surface of the
cerebral hemisphere.
• Each choroid plexus,which has a minutely folded
surface, consists of a core of connective tissue
containing many wide capillaries and a surface
layer of cuboidal or low columnar epithelium.
• The duty of this part is production of CSF
.
• In the lateral ventricles, the choroid plexus is
always bound to a thin cleft called the choroid
fissure.

47. Choroid plexus and choroid fissure-location over view
Location
Lateral ventricle
Inferior horn
Body
Atrium
Third ventricle
Through foramen
of monro
Fourth ventricle
Through cerebral
educate

48. Choroid plexus supply-over view
Supply
Lateral ventricle
Anterior choroidal
artery
branch of internal
carotid artery
lateral posterior
choroidal arteries
branch of the posterior
cerebral artery
Third ventricle
medial posterior
choroidal arteries
branch of posterior
cerebral artery
Fourth ventricle
posterior inferior
cerebellar arteries

49. Subcortical structures
• Definition:
• Islets of gray matter found beneath the cerebral cortex,
organized in several distinctive parts of the brain.
• parts:
• Diencephalon
• Thalamus
• Hypothalamus
• Epithalamus
• pituitary gland
• limbic structures
• basal ganglia

50. Basal ganglia
• The basal ganglia, which are not ganglia but
nuclei, are the:
• corpus striatum of the telencephalon,
• subthalamic nucleus of the diencephalon,
• and substantia nigra of the mesencephalon.
• N. accumbanse
• found deep within the white matter of the
brain. They form a part of the extrapyramidal
motor system and work in tandem with the
pyramidal and limbic systems.

51. Striatum-over view
Striatum
Dorsal Stratum
n. Caudate
Head
Body
Tail
n. Lenticular
Putamen
Globus
pallidus
Ventral

52. Corpus striatum-caudate nucleus
• Caudate nucleus:
• With putamen are The main input to the basal ganglia.
• Lies deep to the internal capsule and anterior to the
thalamus.
• The caudate nuclei are located near the center of the
brain, sitting astride the thalamus
• The caudate nucleus bulges into the lateral ventricle.
• C-shape structure: follows the shape of lateral
ventricle.
• it is comprised of:
• head
• body
• tail
• arched structure

53. caudate nucleus-head
• Caput in Latin.
• Anterior portion of the caudate
nucleus.
• Makes up the a bulge as the floor of
anterior (frontal) horn of the lateral
ventricle.
• The caudate head receives its blood
supply from the lenticulostriate
artery.
Head of caudate nucleus

54. Caudate nucleus-body and tail
• Body:
• It is located between the tail and head.
• It curves downward and follows the curvature of the ventricle into
the roof of the inferior horn of lateral ventricle.
• Tail:
• It forms the roof of the inferior horn of the lateral ventricle.
• the first part of the tail lies along the lateral margin of the central
part of the ventricle.
• The tail follows the contour of the lateral ventricle into the roof of
its temporal horn.
• It arches over the ventral surface of the thalamus, enters the
temporal lobe and terminates by connecting with the amygdala.

55. Caudate nucleus-photos
Head
T
ail

56. Transverse and coronal section

57. Caudate nucleus-photos
Body
T
ail Head

58. Caudate nucleus-lateral ventricle
Anterior horn of
lateral ventricle
Head of caudate
nucleus
Body of caudate
nucleus
Inferior horn of lateral
ventricle
Tail of caudate nucleus
Roof of inferior horn
Body of lateral
ventricle
Posterior horn of lateral
ventricle

59. Lentiform nucleus
• It is made up of 2 parts:
• Putamen
• globus pallidus
• With the caudate nucleus, it forms the striatum.
• It is a large, lens-shaped mass of gray matter just
lateral to the internal capsule.
• is found lateral to the head of the caudate nucleus
and thalamus.
• The lateral aspect of the lentiform nucleus is
referred to as the putamen, and is closely related to
the claustrum and the insula

60. Putamen
• The putamen is a round structure situated at
the base of the forebrain.
• It is the most lateral of the basal ganglia on
the axial section of the brain.
• The putamen and caudate nucleus together
form the dorsal striatum
• The putamen is the lateral part of the
lentiform nucleus.
• it extends beyond the globus pallidus in all
directions except at the base of the nucleus.

61. Putamen
Putamen
Putamen

62. Lentiform nucleolus

63. Globus pallidus
• The globus pallidus (GP), also known as
paleostriatum or dorsal pallidum,is a subcortical
structure of the brain.
• The narrow part of the N. lentiform , facing
medially, is occupied by the globus pallidus, which
is divided into external and internal parts by a
lamina of white matter.
• The globus pallidus is a major component of the
basal ganglia, with principal inputs from the
striatum.
• a paired subcortical structure, situated medially to
the putamen and composed of inhibitory
GABAergic projection neurons, which fire
spontaneously and irregularly at high frequency.
LA
TERALAND MEDIALL P
ART OF
THE GEELOBUS PALLIDUS

64. Globus pallidus
ASPECTS
SUPERIOR
MEDIAL
INFERIOR
ANTERIOR
in contact with the
internal capsule
is in contact with the
subthalamic nucleus and
zona incerta, which
separate it from the
thalamus.
Anteriorly, the globus
pallidus is closely
related to the substantia
innominata and the
hypothalamus.

65. Globus pallidus
:
A category of white matter
which separates 2 parts of
globus pallidus
Globus pallidus

66. Substantia nigra
• a small motor nucleus
• Located in the cerebral peduncle of midbrain.
• Influences the motor output of brain.
• Dopamine synthesis site
• It can be distinguished easily by its black brownish pigments.
• consists of two parts :
• pars compacta: it comprises the dorsal portion of the substantia nigra. It consists of numerous
closely packed melanin-filled neurons that give the substantia nigra its distinctive dark color.
• pars reticulata: it lie ventral to pars compacta. It is larger than the pars compacta, but it
contains fewer cells than it.
• Medially to the substantia nigra is a zone called the ventral tegmental area. It is a small group
of scattered cells that have similar functions to the pars compacta and may really be
considered as an extension of this part.
• It is black substance. Large nucleus with motor functions in the midbrain; many of the
constituent cells contain melanin

67. Substantia nigra
Substantia nigra
Substantia nigra

68. Subthalamus
• Subthalamus: Region of the diencephalon beneath the thalamus, containing fiber
tracts and the subthalamic nucleus.
• has motor functions.
• The subthalamus contains sensory fasciculi, fiber bundles from the cerebellum
and the globus pallidus, rostral extensions of midbrain nuclei, and the
subthalamic nucleus.
• The biconvex subthalamic nucleus (body of Luys) lies against the medial side of
the internal capsule.
• The subthalamic nucleus has reciprocal connections with the globus pallidus.
These fibers constitute the subthalamic fasciculus, which cuts across the internal
capsule. The sensory fasciculi are the medial lemniscus, spinothalamic tract, and
trigeminothalamic tracts. They are spread out immediately beneath the ventral
posterior nucleus of the thalamus, in which the fibers terminate.

69. Subthalamic nucleus
The subthalamic nuclei are composed of excitatory
glutamatergic projection neurons. It receives excitatory
inputs from the frontal cortex in a somatotopically
organized manner. Based on this, the subthalamic nucleus
is divided into three parts:
• The dorsal (motor) part, which receives inputs from the
primary motor cortex
• The ventrolateral (associative) part, which receives
inputs from the prefrontal cortex and frontal eye fields,
and
• The ventromedial (limbic) part, which receives inputs
from the anterior cingulate cortex.

70. Subthalamic nucleus
Subthalamic nucleus
Subthalamic nucleus

71. Internal capsule
The internal capsule is a white matter structure
situated in the inferomedial part of each cerebral
hemisphere of the brain.
The internal capsule consists of:
• an anterior limb
• a genu
• a posterior limb
• retrolentiform part
• sublentiform part
• Function :
• It carries information past the basal ganglia,
separating the caudate nucleus and the thalamus from
the putamen and the globus pallidus.

72. Internal capsule
Anterior limb
Genu
Posterior limb

73. Internal capsule-anterior horn
• The anterior limb is bounded by the lentiform
nucleus and by the head of the caudate nucleus.
• It contains:
• fibers running from the thalamus to the frontal
lobe
• fibers connecting the lentiform and caudate nuclei
• fibers connecting the cortex with the corpus
striatum
• fibers passing from the frontal lobe through the
medial fifth of the base of the cerebral peduncle to
the nuclei pontis.
• thalami pontine fibers
Anterior horn

74. Internal capsule-genu
• The genu is located medially to the apex of
the lentiform nucleus, and the posterior
limb intervenes between the lentiform
nucleus and the thalamus.
• It is formed by fibers from the
corticonucear tract.
• The fibers in this region are named the
geniculate fibers.
• It contains the corticobulbar tract, which
carries upper motor neurons from the
motor cortex to cranial nerve nuclei that
mainly govern motion of striated muscle in
the head and face.

75. Internal capsule-posterior horn
• It is posterior to the genu.
• The anterior two-thirds of the occipital part of the internal capsule contains
fibers of the corticospinal tract.
• It contains:
• sensory fibers, largely derived from the thalamus, though some may be
continued upward from the medial lemniscus
• the fibers of optic radiation, from the lower visual centers to the cortex of the
occipital lobe;
• acoustic fibers, from the lateral lemniscus to the temporal lobe
• fibers that pass from the occipital and temporal lobes to the pontine nuclei

76. Internal capsule-posterior horn
Posterior limb

77. Internal capsule
Internal capsule
Note:
In this image the putamen and globus
pallidus are removed to have a good
show of internal capsule
Anterior limb
Posterior limb

78. Internal capsule
Internal capsule
Horizontal cut

79. N. Accumbance
• The nucleus accumbens is found in an area of
the brain called the basal forebrain. There is
a nucleus accumbens in each cerebral
hemisphere.
• Located between caudate and putamen and is
formed by fusing of these parts.
• The nucleus accumbens is considered part of
the basal ganglia and also is the main
component of the ventral striatum.
• The most widely recognized function of the
nucleus accumbens is its role in the "reward
circuit" of the brain

80. Rhinencephalon
• also called the smell-brain or olfactory
brain (nose-brain)
• Olfactory Areas of the Cerebral
Hemisphere.
• The term is now restricted to the regions
that receive afferent fibers from the
olfactory bulbs.
• This part of brain is classified differently in
sources.
• Part of forebrain

81. Rhinencephalon
Olfactory bulb
Olfactory tract
Anterior olfactory
nucleus
Striae
Medial
Intermediate
Lateral
Olfactory cortex
Amygdala
Uncus
Piriform cortex Primary olfactory
cortex
Entorhinal Anterior
parahipocampus gyrus
Secondary olfactory
cortex

82. Olfactory bulb
• It is a neural structure of the vertebrate
forebrain involved in olfaction, the sense of
smell.
• Cellular Layers of olfactory bulb:
• Glomerular layer
• External plexiform layer
• Mitral cell layer
• Internal plexiform layer
• Granule cell layer
• the olfactory bulb has one source of sensory
input (axons from olfactory receptor neurons of
the olfactory epithelium), and one output
(mitral cell axons)

83. olfactory tract and olfactory trigon
the olfactory tract is a bilateral bundle
of afferent nerve fibers from the mitral
and tufted cells of the olfactory bulb
that connects to several target regions
in the brain, including the piriform
cortex, amygdala, and entorhinal
cortex.
Olfactory trigon:
The end of the olfactory tract which is
a little larger than the parts above.

84. Mitral and tufted cells
mitral cells are neurons that are part of the olfactory
system. They are located in the olfactory bulb in the
mammalian central nervous system. They receive
information from the axons of olfactory receptor neurons,
forming synapses in neuropils called glomerul.
Tufted cells are found within the olfactory glomeruli.[1]
They receive input from the receptor cells of the olfactory
epithelium found in areas of the nose able to sense smell
Axons of these cells make the olfactory tract

85. Olfactory striae
Olfactory
tract
division
Anterior
and
posterior to
the optic
chiasma
Medial
Projects in to the: 1-
anterior commissural
2-septal area
Lateral
continues on to
structures associated
with the olfactory
cortex.(piriform corte)
Intermediate
Anterior perforated
substance
Optic chiasma

86. Stria photos
Medial olfactory striae Lateral olfactory striae
Anterior
commissure

87. Anterior perforated substance and olfactory tubercle
• From the olfactory trigon there is a
intermediate striae .
• This striae is continued to a substance
that is called anterior perforated
substance.
• This substance is covered by a gray
matter that is called olfactory tubercle.

88. Medial pathway
• Some fibers go to the medial olfactory striae
• Travel along and in to the anterior commissure to the cantrolateral
side.
• Then back down through the medial striae
• Then they affect and excites the granular cells.
• These are inter neurons thus they are inhibitory neurons.
• Hence these signals from contralateral side will inhibit the microcell
activities in contralateral bulb.

89. Lateral olfactory striae output
• 1- anterior olfactory nucleus
• 2-olfactory tubercle
• Piriform cortex :
• Amygdala
• Uncus
• Anterior parahippocamous gyrus

90. Olfactory cortex
Olfactory
cortex
Primary
Piriform
Priamygdaloid
Secondary Entorhinal area

91. Olfactory cortex
• This cortex is not a single structure, rather, it is defined as the
combined areas of the cerebral cortex (generally within the temporal
lobe) that receive input directly from the olfactory bulb. These regions
include the:
• Piriform cortex: which is located below the lateral olfactory stria.
• Amygdala: which is located anterior to the temporal/inferior horn of
the lateral ventricle, and is associated with the emotion of fear.
• Entorhinal cortex: which is the anterior part of the parahippocampal
gyrus, and is involved in the formation of memory.

92. Sources
Wikimedia.com
Kenhub.com
Ncbi.com

93. Appreciate your attention
Dr Roya Basser
Azerbaijan medical
university
2020-2021