cns

1. Internal structures of hemispheres
Make it easy

2. Fibers

4. white matter fibers
 White matter is composed of myelinated
axons (nerve fibers) + neuroglial cells +
blood capillaries.
 actively affects how the brain learns and functions.
While grey matter is primarily associated with
processing and cognition, white matter modulates
the distribution of action potentials, acting as a relay
and coordinating communication between different
brain regions

5. Types
commissural fibers
projection fibers
Association fibers

6. Types
 connects region of the 2 hemispheres.
 example:
1-corpus callosum (largest bundle).
2- anterior commissure .
3- posterior commissure .
commissural fibers

7. Types
commissural fibers
projection fibers
Association fibers

8. Types
 Links different cortical area of the same
hemisphere.
 2 types:
1- short association fibers:
small bundle of fibers that connect adjacent gyri
2- long association fibers :
For distant gyri, bundled together to make named
structures.
Example: Cingulum within cingulate gyrus
Connects frontal and parietal lobes with temporal
Association fibers

9. Types
commissural fibers
projection fibers
Association fibers

10. Types
 fibers that pass from the brainstem reaching various
regions.
 Exampels :
Cut the brain
cut in the middle of the hemisphere
fibers will look like a fan and these projection fibers
projection fibers

12.  Exampels :
 1- corona radiata :
Fibers which are dorsal (above ,superior)to the basal
ganglia and close to the cortex .
divided into (radiations)
-Eg. optic radiation, auditory radiation.
 2- A.internal capsule
B. external capsule
C.extreme capsule
projection fibers
Fibers
travelling
between
“around” basal
ganglia

14. Basal nuclei
 masses of grey matter embedded in white matter.
 Cotrex ???

15. Basal nuclei

16. Pale globe
lens
Basal nuclei

17.  thin line of grey matter
 its function isn't well known
Basal nuclei
Claustrum barrier

18. Thalamus
 sensory station of the body
 not a part of basal nuclei
 used as a landmark to define different projection
fibers .

19.  The fibers travelling between lentiform nucleus and
caudate and between lentiform and thalamus is
called
 Between 2 limbs there is a structure like a knee»»
the genu of internal capsule .
projection fibers
internal capsule

20. projection fibers
 The fibers travelling between lentiform nucleus and
claustrum is called
external capsule

21.  The bundle between the claustrum and insula is
called
projection fibers
extreme capsule

24. Insula

25. Fibers

26. Other internal structures of cerebral
hemisphere :
❶septum pellucidum : double membrane)
 delicate membrane “part of anterior horn of lateral
ventricle”.
 bounded by corpus callosum superiorly and fornix
inferiorly.

27.  Fornix
(bundles of fibers that originate from hippocampus.

28. Other internal structures of cerebral
hemisphere :
❶septum pellucidum : double membrane)
 delicate membrane “part of anterior horn of lateral
ventricle”.
 bounded by corpus callosum superiorly and fornix
inferiorly.
 Inner surface of septum pellucidum composed of
ependymal cell, because this surface considered as
part of the wall of the lateral ventricle.
 we have 2 septum pellucidum (cavumpellucidum
separate between them).
 composed of both gray and white matter . (although
it appears white in fresh specimen of brain ) .

30. fresh specimen of brain

31. ❷corpus callosum :
 the largest bundle of commissural fibers .
 Covered with:-
1.rostrum (the smallest)
2.genu(most anterior)
3.body( the largest)
4.splenium(most posterior) .
Other internal structures of cerebral
hemisphere :

32. Ventricles
 Four CSF-filled cavities located within the brain .
 Lined by ependymal cells .
 Contain specialized vascular structures called
:choroid plexuses »» synthesis of CSF .

33.  3rd ventricle in diencephalon
 4th in hindbrain
 cerebral aqueduct in midbrain .

34. ❶Lateral ventricles
 C-shaped of lateral ventricle to allow it to extend to
all lobes of brain.
 Each lateral ventricle is connected to 3rd ventricle by
foramen of monro . 2 in number
 3rd ventricle connected to
4th by cerebral aqueduct
then continue as central
canal of spinal cord .
Does not contain choroid
plexus .

35.  Body » in parietal lobe .
 Ant.horn » in frontal lobe .
 Post. Horn » in occipital lobe .
 Inf. Horn » in temporal lobe .

36.  Interthalamic connection : Bridge of tissue running
through the 3rd ventricle connecting the 2 thalami .
❶Lateral ventricles

37. 4th ventricle
 Tent shaped cavity
 Anterior to cerebellum, Posterior to pons and
medulla oblongata
 Communicates with subarachnoid space through:
-foramen of magendie(1 in number) » central .
-foramen of luschka
(2 in number ) » lateral .

38. MRI

39. Choroid plexuses
 Invagination of pia matter with blood capillaries
inside it, found through ventricles
 Components :
-Endothelial layer(fenestrated)
-Pial membrane.
-Choroidal epithelial cells :form the blood
-CSF barrier and responsible of active transport of the
substances in and out of CSF

40. CSF
 We have 150 ml of CSF in our body due to high
turnover. “subarachnoid space”
 Only 20 ml of CSF in ventricles (less than 50%).