white fibers of the cerebrum, commissural fibers, association fibers and radiation fibers, examples of each types of cerebral fibers, corpus callosum, fornix, habenular commisure, anterior commissure, posterior commissure, superior longitudinal fasciculus, inferior longitudinal fasciculus, occipital fasciculus, uncinate fasciculus, projection fibers, corona radiata, optic radiation

1. WHITE FIBERS OF
CEREBRUM
DR SANA YASEEN
ANATOMY DEPARTMENT
KIMS

2. TYPES OF WHITE MATTER
 There are three main types of white matter nerve fiber tracts: commissural
fibers, association fibers, and projection fibers.
 Commissural fibers connect corresponding regions of the left and right
hemispheres of the brain.
 Association fibers connect brain regions within the same hemisphere.
 Projection fibers connect the cerebral cortex to the brainstem and spinal
cord.

4. COMMISSURAL FIBERS

5. COMMISSURAL FIBERS
 Commissural fibers connect corresponding regions of the left and right brain
hemispheres.
 Such as:
 Corpus callosum
 Fornix
 Anterior commissure
 Posterior commissure
 Habenular commissure

6. CORPUS CALLOSUM
 Is largest C-shaped thick bundle of fibers
located within the medial longitudinal fissure,
beneath the cerebral cortex across te midline.
 The corpus callosum connects the left and right
frontal lobes, temporal lobes, and occipital
lobes.
 PARTS OF CORPUS CALLOSUM: (from anterior
to poateriorly)
ROSTRUM –GENU- BODY/ TRUNCK- SPLENIUM

9. RELATIONS
 Suprior surface is covered by thin layer of gray matter : INDUSIUM GRISEUM
 Immediately above: interhemispheric fissure in which runs falx cerebri and
branches of anterior cerebral hemisphere
 On either side: body is separated from cingulate gyrus by callosal sulcus
 Inferior: thin vertical septum pellucidum anteriorly and fornix and its
commissure posteriorly

11.  ROSTRUM: is thin anterior end, posteriorly continue with upper end of internal capsule
 GENU: is crved anterior end of corpus callousm and fibers running through curves
anteriorly in frontal lobe and formes “ FORCEP MINOR”.
 BODY: is upper curved part of corpus calloum. Fibers running thorugh radiates out
laterally as “RADIATION OF CORPUS CALLOSUM” and runs aong with corona radiata to
reach cerebral cortex.
 SPLENIUM: is thickened posterior portion of corpus callosum. Fibers curved posteriorly
into occipital lobe as “FORCEP MAJOR”.
 TEPTUM:
PARTS CORPUS CALLOSUM

14. ANTERIOR COMMISSURE
 The anterior commissure present in
the anterior wall of the third ventricle
in the upper end of lamina terminalis.
 The anterior commissure is divided
into an anterior and a posterior
bundle when traced laterally,
 Anterior bundle curves anteriorly to
anterior perforated substance and
olfactory tract.
 posterior half passes underneath the
lentiform nucleus of the basal ganglia.

15. POSTERIOR COMMISSURE
 Located just below the stalk of pineal
gland and above the opening of
cerebral aqueduct into third ventricle
 Is associated with numerous nuclei
present around it and also recieves
fibers from thalamic, pretecta nuclei
and superior colliculus
 Exact function is unknown, fibers of
pretectal ncleus is associaed with
pupillary light reflex.

16. CORPUS
CALLOSUM
FORNIX
POSTERIOR
COMMISSURE
ANTERIOR
COMMISSURE

17. FORNIX
 Is C-shaped bundle of nerve fibers that arches around thalamus and act as major
out put tarct of hippocampus.
 COMPONENT:
 ALVEUS
 FIMBRIA
 POSTEIOR COLUMN OF FORNIX
 COMMISSURE OF FORNIX
 BODY
 ANTEIOR COLUMN OF FORNIX

19. RELATION OF FORNIX
 Superiorly: corpus callosum
 Posteriorly: posterior commissure
 Anteriorly: anterior commissure
 Inferiorly: thalamus
 Medially: 3rd ventricle

22. HABENULAR COMMISSURE
 band of nerve fibers that are
positioned above the pineal
stalk and connect the
habenular nucleus of each
brain hemisphere.
 Habenular nuclei are nerve
cells of the epithalamus and
a component of the limbic
system

23. Third
ventricle
Habenular
commissure
Pineal gland
Superior
colliculi

24. ASSOCIATION FIBERS

25. ASSOCIATION FIBERS
 Association fibers connect cortex regions within the same hemisphere.
 There are two types of association fibers:
 Short association fibers
 Long association fibers.
 Short association fibers are found just below the cortex. These fibers
connect brain gyri.
 Long association fibers connect cerebral lobes within brain regions.

26. Superior Longitudinal
Fasciculus
 long association fiber tracts that
connect the temporal, frontal,
and occipital lobes.
Inferior Longitudinal
Fasciculus
 long association fiber tracts that
connect the occipital and
temporal lobes.
Occipitofrontal Fasciculus
 association fibers that
branch into superior and
inferior tracts that connect
the occipital and frontal
lobes.
Uncinate Fasciculus
 long association fibers that connect the
frontal and temporal lobes of the cortex.

27. Cingulum
 band of fibers located within
the cingulate gyrus that
connect the cingulate gyrus
and frontal lobes with the gyri
of the hippocampus (also
called parahippocampal gyri).
Arcuate Fasciculus
 long association fiber tracts
that connect frontal lobe gyri
with the temporal lobe.

29. PROJECTION FIBERS

30. PROJECTION FIBERS
 Projection fibers connect the cerebral
cortex to the brainstem and spinal
cord.
 These fiber tracts help to relay motor
and sensory signals between the
central nervous system and peripheral
nervous system.
 Such as ;
 Corona radiata
 Optic radiation

31. CORONA RADIATA
 a fan-shaped mass of
white matter fibers
passing to and from the
cerebral cortex.
 The fibers as emerges
from the internal capsule
they radiate as they
approaches the cerebral
cortex.

33. OPTIC RADIATION
 Also known as the
geniculocalcarine tract,
the geniculostriate
pathway, and posterior
thalamic radiation
 The optic radiation are
axons from the neurons
in the lateral geniculate
nucleus to the primary
visual cortex