General thing about brain

2. 




is the largest and upper part of C.N.S.
1360 gm
The brain (encephalon) lies within the cranium
The brain receives information from, and
controls the activities of, the trunk and limbs
mainly through connections with the spinal
cord.
It also possesses 12 pairs of cranial nerves
through which it communicates mostly with
structures of the head and neck.

3. 
Five divisions:
Cerebrum: largest part
 Cerebellum: lies below the posterior part of
cerebrum.
 Midbrain
 Pons
 Medulla


5. Brain is divided into five parts embryologically:
1.
Telencephalon (cerebrum and basal ganglia).
2.
Diencephalon(thalamus,hypothalamus,epithal
amus,subthalamus and metathalamus:
1 and 2 = forebrain, with a cavity lateral
ventricles and third ventricle respectively.
3.Mesencephalon (mid brain), with a cavity of
cerebral aqueduct.

6. 4. metencephalon( pons and cerebellum),with a
cavity of upper part of 4th ventricle.
5. myelencephalon( medulla oblongata), with a
cavity of lower part of 4th ventricle.
4 and 5=hindbrain, with a cavity of 4th ventricle.
Medulla oblongata, pons and mid brain=brain
stem.
The cerebellum, pons and medulla are collectively
called hind-brain

8. 

fibrous and delicate membranes that are
internal to the skull.
from outer to inner are: dura—arachnoid---pia matter.

10. Skin
Galea Aponeurotica
Connective Tissue
Bone
Dura Mater
Arachnoid mater

11. 
Arachnoid:



Loose spider-web of
connective tissue.
Beneath it is the
subarachnoid space –
filled with blood
vessels and CSF
Pia



Deepest and most
delicate
Covers the brain tissue
Follows its every ridge
and groove

14. 


Epidural space- is a potential space between
periosteum covering the calvaria and dura.
contains middle meningeal arteries in the
cranial cavity
Sub dural space- is a potential space between
dura and arachnoid

15. 




Is the tough, external, thick, fibrous two
layered membrane of the meninges.
Is external to subdural space and internal to
epidural space
is made up of two layers
an external periosteal layer
an internal meningeal layers.

16. 



The two layers difficult to separate at some
poins (firmly fused)
Hence look single but at some areas they are
not firmly attached (unfused)
Form a potential space –dural venous sinuses
It forms dural venous sinuses, spaces between
periosteal and meningeal layers

17. 


Large veins from the surface of the brain
empty into these sinuses and most of the
blood from the brain
Ultimately drains through them into IJVs
.

18. 1. Superior saggital sinus (S):
 lies in the midline along the convex border of
the falx cerebri.
 Begins at the crista galli ends internal occipital
protuberance at confluence of sinuses (meeting
place of SSS,SS,OS and TS
 receives the cerebral ,diploic (cranial
vein), meningeal and parietal emissary veins

19. 2- Inferior saggital sinus (S):
 lies in the free age of falx cerebri
 is joined by great cerebral vein (of Galen) to
form straight sinus (union of ISS with great
cerebral vein).

21. 3- Straight sinus (S): runs along the line of
attachement of the falx cerebri to the tentorium
cerebelli.
4- Transeverse sinus (P): runs laterally from
confluence of sinuses along the edge of the
tentorium cerebelli.

22. 5- Sigmoid sinus (P);
 is a continuation of the transverse sinus, arches
downward and medially in an S-shaped
groove on the mastoid part of the temporal
bone

enters the superior bulb of IJV (becomes
continous as)

24. 6- Cavernous sinus (P):
 are located on each side of sella turcica, on
body of sphenoid bone.
 The ICA and abducent nerve pass via the sinus


occulomotor, trochlear, opthalmic, and
maxillary nerves pass foreward in the lateral
wall of the sinus.
Communicates with pterygoid plexus by
emissary veins and receive superior opthalmic
vein.

26. 7- Superior petrosal sinus (P):
 lie in the margin of the tentorium cerebelli,
 Running from the posterior end of the veins making
up the cavernous sinus to the transeverse sinuses
 The site where these sinuses curve inferiorly to form
sigmoid sinuses.
8- Inferior petrosal sinus (P):
 Drains the cavernous sinus into the bulb of the IJV
 Runs in a groove between petrous part of temporal
bone and the basilar part of occipital bone.
 Basilar plexus connects IPS with internal vertebral
venous plexus

27. 9- Sphenoparietal sinus (P): lies along the posterior edge
of the lesser wing of sphenoid bone and drains to
cavernous sinus.
10- Occipital sinus (S): lies in the falx cerebelli and drains
into the confluence of sinuses
11- Basilar sinus (plexus, S): consist of interconnecting
venous channels on the basilar part of occipital bone and
connects the two inferior petrosal sinus.

Communicates with the internal vertebral venous
plexus.

29. 
At the certain places the inner layer of the dura
is stretched and reduplicated to form the
followings folds:

30. 



Sickle-shaped
Lies in the median groove between the two
cerebral hemispheres.
Is attached anteriorly to crista galli and
posteriorly to the tentorium cerebelli.
Its inferior concave border is free and contains
inferior saggital sinus,and its upper convex
margin encloses the superior saggital sinus.

32. 





Tent-like or crescentric
Occupies the cleft between the posterior part of the
cerebrum and the cerebellum .
Its internal concave border is free and bonds to
tentorial notch.
its external convex border encloses transverse sinus
posteriorly and the superior petrosal sinus anteriorly.
The free border is attached to the anterior clinoid
process,
the attached border is attached to the posterior clinoid
process.

34. 



Sickle-shaped
Occupies the posterior notch of the cerebellum
Is attached to the posterior and inferior parts of
the tentorium.
Contains occipital sinus in its posterior border.

35. 

Is circular, horizontal fold of dura that forms
the roof of sella turcica,covering the pitutary
gland or hypophysis.
Has a central aperture for the hypophyseal
stalk or infundibulum.

36. 


Anterior and posterior ethmoidal branches of
V1 in the anterior cranial fossa
Meingeal branches of maxillary V2 &V3 in the
middle cranial fossa.
Meningeal branch of the CN X and by tentorial
nerve (V1) in the posterior cranial fossa.

37. 



Dura is supplied by
Middle meningeal artery which has anterior
and posterior branches, from 1st part of
maxillary artery(via foramen spinosum)
Acessory meningeal artery from 1st part of
maxillary artery (via foramen ovale)
Meningeal branches of opthalmic, occipital and
vertebral arteries.

38. Veins accompanying the arteries drain into
pterygoid plexus of veins.

40. 


Is a filmy, thin, transparent, and delicate
membrane that is connected to pia matter by
web-like trabeculations.
Separated from the dura by a capillary
interval, the subdural space which is occupied
by a film of to fluid to moisten and connective
tissue.
The space between the arachnoid and pia is
called the subarachnoid space.

41. 



Filled with C.S.F.
Contains fine filaments and trabeculae
connecting the arachnoid to the pia
The blood vessels of the brain lie in it.
In certain places the subarachnoid space is
enlarged to form subarachnoid cisterns which
contains CSF and soft tissue structures
that‖anchor‖ the brain, such as arachnoid
trabeculae, vasculature, and in some cases
cranial roots. They are named according to the
structures related them.

42. Formed by wide separation of the arachnoid
from the pia. The cisterns are.
 Cerebellomedullary cistern (cisterna magna)
Site: between the back of the medulla and the
lower part of the cerebellum divides into
postrior and lateral. Receives CSF from the
aperature of 4th ventricle
pontine cistern
Site: in front of the pons it continues with
spinal subarachenoid space
Contains: the vertebral and basilar arteries.

43. Interpeduncular cistern:
Site: interpedunculaar fossa b/n cerebral peduncles
of the mid brain.
Contains: the arteries which form the circulus
arteriosus
 Chiasmatic cistern
Site optic chiasma.
Cistern of the lateral sulcus (Ambient):
Site: lateral sulcus (lateral aspect of the mid brain
continous posteriorly with quadrigeminal cistern)
Contains: middle cerebral vessels.


45. 
Cistern of corpus callosum (quadrigeminal
cistern)
Site: above the corpus callosum or posterior
part of the corpus callosum & superior surface
of cerebellum. It contains parts of the great
cerebral vein.
Contains: the anterior cerebral artery

46. 



Pedunculated projections from the arachnoid mater which
tend to push themselves inside the venous sinuses of the
dura.
are tuft-like collections of highly folded arachnoid that
project into the superior saggital siunus and the lateral
lacunae, which are lateral extensions of the superior saggital
sinus.
absorb CSF into dural sinuses and often produce erosion or
pitting of the inner surface of clvaria (indent bones)
They protrude through the meningeal layer of the dural
matter into dural venous sinuses, especially the lateral
lacunae, and effect transfer of CSF to venous system.

48. 

They are found in large number along there
superior sagittal sinus.
Their function is to allow the filtration of C.S.F
from the subarachnoid to the blood stream in
the superior sagittal sinus.

50. 
It is the thinnest and most delicate membrane
of the brain.

Covers the gyri and dips into fissures and sulci.

enmeshes blood vessels on the surface of the
brain.

Invaginates the interior of the brain forming
folds of pia called tela chorioidea which
produce C.S.F.

51. What is leptomeninges?
Pia-arachnoid, because they develop from a
single layer of mesenchyme surrounding the
embryonic brain.


52. 
Dura-skull interface(extradural or epidural space.

Dura-arachnoid interface(subdural)space.

Arachnoid-pia interface(subarachnoid)space.

53. Epidural hematoma:
 is due to rupture of middle meningeal artery.
Subdural hematoma:
 is due to rupture of cerebral veins as they pass
from brain surface into one of the venous
sinuses.
Subarachnoid hemorrhage:
is due to rupture of cerebral arteries.

54. Pial hemorrage:
 is due to damage to small vessels of the pia and brain
tissue.
Cavernous sinus thrombophlebitis:
is an infectious inflammation of the cavernous sinus with
secondary thrombus formation.


Is associated with significant morbidity and mortality
because of formation of meningitis (inflammation of
the meanings
May produce papilla edema(edema of optic
disc, probably due to raised intracranial
pressure), exophthalmoses (protrusion of the eye
ball),and ophthalmoplegia (paralysis of eye muscles)
why?

56. 


The midbrain, pons and medulla lie, one below
the other below the cerebrum and infront of the
cerebellum.
Occupies the posterior cranial fossa of the
skull
They are collectively called (brain- stem).

58. The brainstem has three broad functions:
I.
It serves as a conduit for the ascending tracts
and descending tracts
II.
It contains important reflex centers associated
with the control of respiration and the
cardiovascular system and with the control of
consciousness
III. It contains the important nuclei of cranial
nerves III through XII

60. 

Damage to the brain stem is often devastating
and life-threatening.
Because it is a structurally and functionally
compact region,

61. GENERAL




It is about one inch long
Continuous above with the lower border of the
pons
Continuous below with the spinal cord at the
foramen magnum
Its upper half forms part of the floor of the
fourth ventricle

62. 



Its lower half is tunneled by the central canal
which connects the fourth ventricle with the
central canal of the spinal cord.
According to 4th ventricle M.O divides into two
Upper medulla (open) is motor decussation
Lower medulla (closed) is sensory decussation

63. In the ventral aspect three elevations are present

Pyramid:
Is the bundle that lies alongside the anterior median
fissure.
 Pyramidal decussation: is seen in the lower part of the
medulla.
 Obliterating the lower end of the anterior median fissure
2. Olive
1.

Is the oval elevation that lies lateral to the pyramid.
 Produced by the olivary nucleus.

3. Inferior cerebellar pudencle

65. we have also groves
I.
II.
Anterior median fissure: lies in the middle line
Anterolateral sulcus: Between the olive
and the pyramid.
 The rootlets of hypoglossal nerve come out
along this sulcus
III.
Posterolateral sulcus: Separates the olive
from the inferior cerebellar peduncle
 The rootlets of 9, 10 & 11 cranial nerves come out along this sulus

66. 
Hypoglossal nerve: comes out along the
anterolateral sulcus

Glossopharayngeal, vagus and accessory nerves:
come out along the posterolateral sulcus.

67. posterior median fissure:



Exists only in the lower half
The upper of the posterior surface of the
medulla forms part of the floor of the fourth
ventricle.
Lower medulla
Gracile tract and tubercle :




Slender bundle
lies alongside the posterior median fissure.
Produced by the gracile tract.
Ends a small elevation called tubercle which is
produced by gracile nucleus.

68. Cuneat tract and tubercle :



Slender bundle lateral to the fasciculus gracilis
Produced by the cuneate tract
Ends in small elevation called cuneate tubercle
which is produced by cuneate nucleus.
Inferior cerebellar peduncle




Thick rope – like bundle that lies lateral to the
fasciculus cuneatus.
Begins at the middle of the medulla,
Extends upwards and laterally to reach the
lower part of the back of the pons
It bends sharply back-wards between the
middle and superior cerebellar penduncle to
enter the cerebellum

70. 


Upper ½ of the posterior surface
This belongs to the open medulla
Forms the floor of 4th ventricle

71. The following Features seen: Hypoglossal triangle over lies the hypoglossal nucleus
 lies near to the posterior median sulcus
 Vestibular area Lies in the lateral side of the posterior surface
 Produced by the vestibular nuclei

73. 




Vagal triangleDepressed area b/n vestibular and hypoglossal
Overlies dorsal nucleus of the vagus
Inferior cerebellar peduncle
Forms most lateral elevation in the posterior
surface

75. 




Nerves attached to the medulla
Cranial nerves from 6th -8th are attached at the
junction b/n medulla and pons
From 9th – 12th are attached to the surface of the
medulla
9th, 10th and 11th cranial nerves are attached at
the groove b/n olive and inferior peduncle
The 12th attached in the anteriolateral groove

77. 
Medulla oblongata: TS at the level of pyramidal
decussation
centrally central canal of MO
 Gray matter surrounding the central canal
 decussating pyramidal fibres –separating the ventral
gray column and central gray matter


79. Fasiculus gracilis- occupying the region behind
central gray matter medially
Fasiculus cuenatus: occupying the region behind
central gray matter laterally
Nucleus gracilis: tongue shaped extension central
gray matter medially
Nucleus cuenatus: tongue shaped extension central
gray matter laterally
Spinal nucleus of trigeminal nerve : lateral to nucleus
cuenatus
Cortico spinal fibres: on each side of mid line
Medial lemniscus the region behind pyramid on
each side of mid

81. line




sensory decussaion : crossing fibres of medial
lemniscus
reticular formation: ( scattered neurons mixed with
nerve fibres ) : lateral to medial lemniscus.
mass of white matter.containing various tracts more

83. 
Is Interposed between the medulla (below) and
the midbrain (above) and in front of the
cerebellum.

84. 
Anterior surface:
 median groove: sulcus basilaris (basilar
sulcus of pons) for the basilar artery.
 transverse pontine fibers: form many thick
transverse bundles.
 abducent nerve: emerges between the
pons and the pyramid near the middle
line.

85. 



Lateral surface
Middle cerebellar peduncle:
Thick compact bundle
Formed by the collection of the transverse
pontine fibers.
Sinks in to the corresponding cerebellar
hemisphere

86. 



Roots of trigeminal nerve:
Arises at the point of junction between the pons
and the middle cerebellar peduncle.
Two roots,
a large sensory one medially
a smaller motor one laterally

87. 
Pontocerebellar angle:
Triangular space between the:
 Lower border of middle cerebellar peduncle
 Cerenellum
 Upper part of the medulla.

Facial and auditory nerves:
Attached to the pons in the region of
pontocerebellar angel
Posterior surface:


forms the upper part of the floor of the 4th
ventricle.
Three foramina, F. luschka, F. magendi via this
CSF moves to subarachenoid space to cisterne
magnum

88. PONS :TS via upper part shows :
A . ventral part(basilar)
1. Transverse fibres
2. Vertical fibres – those descending from cerebral
cortexto end in pontine Nuclei.








cortico spinal fibres that descend via pons into the
medulla where they form pyramid
pontine nuclei
middle cerebral peduncle- formed from transverse
fibres laterally toward cerebellum

89. 



on dorsal surface.(tegmentum)
1. tegmentum continuous with
tegmentum of the mid brain superiorly
2. spinal nucleus of trigeminal
nerve- medial to peduncles
3. medial lemniscus and other
fibres

94. 




Definition: is the shortest part of the brain stem
Position: between the pons below and the
thalamus above
Occupies the notch of Tentorium
cerebelli
Mid brain cavity:it is tunneled from end to end
by a narrow channel called aqueduct
which connects the Third ventricle with
the fourth

96. 
two cerebral peduncles






Rope-like bundle of fibres (crus of mid brain)
Pass in to the anterior part of the pons below
Sinks in to the substance of the cerebral hemispheres
above
Posterior to crus there are substancia nigra and
tegmentum respectively
two oculomotor nerves
emerge medial to the cerebral peduncles

97. Contains


corpora quadrigemina (colliculi)











form the tectum
four rounded swellings
a) two superior
b) two inferior
- the superior colliculi are reflex centers for vision
- the inferior colliculi are reflex centers for
hearing
2. Trochlear nerve
- emerge from the dorsal surface
below the inferior colliculi
- the trochlear nerve is the only
cranial nerve which emerges from the
dorsal surface of the brain.
b/n the anterior and dorsal parts (two crura of
mid brain) forms interpedunclar fossae

101. 
superior brachium quadrigeminum composed of
strands of fibres that extend
from the superior colliculus to the lateral
geniculate body.


inferior brachium quadrigeminum :composed of
bundles of fibres that extend from the inferior
colliculus to the medial geniculate body

102. 






Shape :diamond shaped
Site : at the base of the brain anterior to the
pons
Boundaries :
Anteriorly :optic chiasma
Posteriorly : pons
On both sides: 1. optic tract (in front)
cerebral peduncle(behind

104. 

Important structures in the fossa:
posterior perforated substance:



lies in the posterior part of the fossa
formed of a layer of gray matter perforated by the
central branches of the posterior cerebral arteries.
two mamillary bodies :

pair of rounded structrer place side by side
immediately in front of the posterior perofrated
substance

105. MID BRAIN
Tectum part laying behind a horizontal line
drawn via the cerebral aqueduct . Each with
three parts from anterior to posterior are




crus cerebri(basis peduncle)- containing large mass
of vertically running fibres , they descend from
cerebral cortex , some pass via mid brain , to reach
pons , while others reach the spinal cord.
Substantia nigra- is made up of pigmented
gray matter , hence appears dark in color and
its damage leads to parkinson’sdisease

107. 




is the largest part of hind brain.
in the posterior cranial fossa & covered by
tentorium cerebelli
150 gms.
ratio : of cerebellum to cerebrum is 1/8 in
adult & 1/20 in infant.
the cerebellum is composed of two cerebellar
hemispheres connected in the middle by a
central portion called vermis. Its greatest length
is from side to side.

110. 

the superior vermis is not marked clearly from the
upper surface of the cerebellar hemispheres.
The inferior vermis is marked clearly from the inferior
surface of the cerebellar hemispheres as it lies at the
bottom of a deep groove called vallecula cerebelli.
The cerbellum has two notches and two surfaces:
 anterior notch
 posterior notch
 upper surface
 lower surface

111. Anterior notch

Wide and shallow notch

Occupied by the midbrain, pons and medulla
Posterior notch

Narrow and deep

Occupied by a fold of dura called falx cerebelli

112. Upper surface: (superior)
 Looks like a butterfly with outstretched wings;
the superior vermis represents the body of the
butterfly and the two cerebellar hemispheres
represent the wings.

No definite lines of demarcation between the
superior vermis and the upper surface of the
cerebellum

113. Lower surface: (inferior)

Is large and rounded

The two cerebellar hemispheres are separated
by a deep groove, the vallecula cerebelli in
which the inferior vermis lies

The inferior vermis is formed of 3 lobules from
before backwards.

114. 




Nodule
Uvula
Pyramid
Two lateral extensions termed floculus and
parafloculus extend laterally from each side of
the nodule
are separated from the rest of the cerebellum
by postero-lateral fissure.

115. 



Primary fissure: on the superior surface nearly
at the junction of anterior 2/3 with the
posterior one thirds of the superior surface.
Horizontal Fissure:
Sweeps around the margin of the cerebellum
from the anterior notch to the posterior notch
separates the upper and lower surfaces of
each hemisphere.

116. Postero-lateral fissure:
 Separates the flocculus and paraflocculus from
the rest of the cerebellum

Secondary fissure: behind the pyramid

117. 1. Anterior Lobe:
 Is uniformly developed.
 In front of the primary fissure
 Median part: superior vermis in front of the
primary fissure
 Two lateral extensions: superior
surface, anterior to the primary fissure.

118. 
Formed of a narrow median part and a huge
lateral extensions.
 Median part: superior vermis between the primary and
secondary fissures.
 Two lateral extensions: formed by the posterior part of
the superior surface and the greater part of the inferior
surface.

119. 
Formed of a well developed median part
(inferior vermis) and rudimentary pairs of
lateral extensions (flocculus and paraflocculus

123. Superior cerebellar artery
 Origin: basilar artery
 Supplies: superior surface of cerebellum
Anterior inferior cerebellar artery

Origin :basilar artery
 Supplies :anterior part of inferior surface
posterior inferior cerebellar artery
 origin : vertebral artery
 supplies: posterior part of inferior surface

126. Is the cavity of hind brain
 between the cerebellum behind and the pons
and upper part of the medulla in front
 tent-shaped (diamond)
Lateral boundaries:
Upper part: superor cerebellar peduncles
Lower part: inferior cerebellar peduncles


127. Has four angles:

upper angle

lower angle

two lateral angle

128. 


the superior angle is continuous with the
cerebral aqueduct which connects it with the
third ventricle.
The inferior angle is continuous with the
central canal of the medulla.
The lateral angle is the meeting of the superior
and inferior cerebellar peduncles.

129. Roof: looks like a tent



Upper part: formed by the superior cerebellar
peduncles and the superior medullary velum
which consists of ependyma attached to the inner
margins of the superior peduncles
Middle part: cerebellum
Lower part: formed by the inferior medullary
velum which consists of ependyma attached to
the inner margins of the inferior cerebellar
peduncles.

130. Floor: formed

Above: by the back of the pons

Below: by upper part of the back of the medulla.
the floor is divided by transverse band of a
nerve fibers called medullary striae in to:



Pontine portion: above
Medullary portion: below

131. Pontine portion:

Is divided in to two longitudinal halves by
median sulcus

Inferior cerebellar puduncle forms the floor of
the ventricle

132. 



is divided it to two longitudinal halves by median sulcus
on either side of the median sulcus there is a
longitudinal elevation called median eminence
(eminentia medialis)
above the middle of the median eminence there is a
rounded swelling termed the
facial colliculus which is produced by the abducent
nucleus and the encircling facial nerve fibers

133. 




shows a small v- shaped depression called the inferior
fovea .
- the inferior fovea divides the medullary portion
in to three trigones
1. Hypoglossal trigone: medial to the inferior fovea
(for CN 12)
2. vagal trigone: between the limbs of the inferior
fovea (for CN 10)
3. vestibular trigone (for CN 8): lateral to the inferior
fovea

134. 1.median aperture(foramen of magendi) in the
inferior medullary velum(lower part of the roof)
2. lateral aperture(foramen of Luschka) is found
in the lateral recess which is a pocket-like
extension of the fourth ventricle on either sides

135. 


Third ventricle through the cerebral aqueduct
central canal of medulla through its inferior
angle
subarachnoid space through the medial and
lateral apertures

136. 




Four cranial nerve nuclei
Abducent : opposite the facial colliculus
Hypoglossal: hypoglossal trigone
Vagus: vagal trigone
Vestibular: Vestibular trigone

137. 



is composed of right and left cerebral hemispheres
the two hemispheres are to a large extent separated
from each other by a longitudinal fissure.
The longitudinal fissure is complete in front and
behind but is interrupted in the middle by the
corpus callosum .
The longitudinal fissure is occupied by the falx
cerebri.

139. a) Poles of the cerebral hemispheres:
1. Frontal pole – is rounded
- lies opposite the root of the nose and
medial part of the supeciliary arch.
2. Occipital pole- is more pointed
- lies opposite a spot above and lateral to
the external occipital protuberance.
3. temporal pole- is rounded
- fits in to the recesses of the lateral part of
the middle cranial fossa below the lesser wing of sphenoid.

140. b) Borders of the cerebral hemispheres:
1. supero-medial border:
- is the upper margin of the hemisphere
- extends from the frontal to the occipital poles
- lies between the medial and lateral surfaces
2. infero-lateral border:
- extends from the occipital to the temporal poles
- lies between the supero-lateral and inferior surfaces.
- presents a notch ,called pre- occipital notch one and half
inches
in front of the occipital pole

141. 3. super ciliary border:

extends from the frontal pole to the end of the
stem of lateralsulcus.
4. medial orbital:

extends from the frontal pole to the optic
chiasma
5. medial occipital border:

extends from the occipital pole to the corpus
callosum

142. c) Surfaces of the hemispheres:
1. supero-lateral surface
-large and convex
- directed laterally
2. medial surface
- flat
- directed medially
3. inferior surface
-directed inferiorly
-divided by a lateral sulcus into two parts:
a, orbital surface: lies on the roof of the orbit
b, tentorial surface: lies on the tentorium
cerebelli

143. d) sulci which divide the hemeispheres into
lobes:
1. central sulcus
-lies on the lateral surface
2. posterior ramus of the lateral sulcus:
-arise from stem of the lateral sulcus which lies
between the oribital and tentorial surfaces.
3. parieto-occipital sulcus:
-found mainly on the medial surface
-extends for a short distance on the lateral
surface.
4. pre-occipital notch:
-lies on the inferolateral border 1.5in. in the
front of the occipital pole.

144. 1. frontal lobe: in front of the central sulcus
2. parietal lobe: between:
a, central sulcus…….infront
b, upper part of the vertical line…..behind
c., posterior ramus of the lateral sulcus and the
horizontal
line below.
3.occipital lobe: behind the vertical line
4. temporal lobe: below the posterior ramus of the lateral
sulcus and the horizontal line.
5. insular lobe: deep to lateral sulcus, covered by
operculum

146. Frontal lobe
a, sucli of frontal lobes
1. precentral sulcus:
-one fingers breadth infront of the central
sulcus and is nearly parallel to it.
2. superior frontal sulcus:
-begins at the upper part of the precentral
sulcus
-runs forewards parallel to the upper
border.

147. 3. inferior frontal sulcus:
-begins at the lower part of precentral sulcus
-runs forewards parallel to the superior frontal
sulcus.
4. the two anterior rami of lateral sulcus:
-both arise from stem of lateral sulcus
-the anterior horizontal –extends forewards.
-the anterior vertical –extends upwards.

148. b) gyri of the frontal lobe :
1. precentral gyrus:
-between the central and precentral sulci
-contains the motor area of the opposite half of the
body.
2. superior frontal gyrus:
-lies above the superior frontal sulcus
3. middle frontal gyrus:
-lies between the superior and inferior frontal
sulci.
4. inferior frontal gyrus
-lies below the inferior frontal sulcus.

149. c) important areas on the frontal lobe:
1. motor area:
-found in the precentral gyrus
-the body is turned upside down in the areahead,upper limb, trunk,and
lower limb from below
upwards(somatotopicaaly organized).
the area for the lower limb flows over the superiomedial border
into
the paracentral lobule on the medial surface.
premotor area:
-is the region infront of the motor area and parallel to
it.
-is the extrapyramidal motor area for the eye.

150. 1.
2.
3.
4.
Primary Motor Cortex
Premotor Cortex
Broca’s Area
Frontal Eye Field
150

151. Premotor cortex
Primary motor
cortex
Frontal
Eye
Field
Broca’s Area
151

152. 
Somatotopy
- The entire body is
represented spatially in
the primary motor cortex,
i.e., in one region we have
neurons controlling hand
movements and in another
region leg movements, etc.
- Neurons controlling
movement of different
body regions do not
intermingle.
152

153. 
Located in the
precentral gyrus
of each cerebral
hemisphere.
 Allowing for
voluntary motor
control.
153

154. 154

155. 




3. frontal eye field area:
-lies in the posterior part of the middle
frontal gyrus
- is the pyramidal motor area for the
eye.
4. Broca’s motor area of speech;
-found in the posterior part of the
inferior frontal gyrus in the left hemisphere (in
right handed people).

156. 


Located just
anterior to the
primary motor
cortex.
Involved in
learned or
patterned skills
Involved in
planning
movements
156

157. 


Typically found in
only one hemisphere
(often the
left), anterior to the
inferior portion of
the premotor cortex
Directs muscles of
tongue, lips, and
throat that are used
in speech production
Involved in planning
speech production
and possibly
planning other
157

158. 


Controls
voluntary eye
movements
Found in and
anterior to the
premotor
cortex, superior
to Broca’s area
What muscles
would be
affected if this
area was
damaged?
158

159. 


Found in the
frontal lobe just
above the orbits
Receptors in the
olfactory
epithelium extend
through the
cribriform plate
and are excited by
the binding of
oderants. They
then send their
info to the
olfactory cortex
Very much
159

160. 160

161. Sulci of the parietal lobe:
postcentral sulcus:
one finger’s breadth behind the central sulcus and
is mearly parallel to it.
Intraparietal Sulcus
Begins close to the middle of the postccentral
sulcus and runs backwards to the occipital lobe.

162. 

Gyri of the partietal lobe:



the up turned posterior parts of
 posterior ramus of lateral sulcus.
 Superior temporal sulcus.
 Inferior temporal sulcus.
postcentral gyrus:
between the central and postcentral sulci.
Contains the sensory area for the opposite half
of the body

163. 



Superior parietal lobule: is the part above the
intraparietal sulcus.
inferior parietal lobule: is the part of below the
intraparietal sulcus.
supramarginal gyrus: surrounds the upper
endd of the posterior ramus of the lateral slcus.
angular gyrus: surrounds the upper end of the
superior temporal sulcus.

164. 




sensory area
Found in the postcentral gyrus
As in the motor area the body is represented
upside down.
The sensory area for the lower limb extendes
over the superomedial border in to the
paracentral lobule on the medial surface.
The center for the strage of the memory of
written and printed wores is found in the
supramarginal and angular gyri

165. 


Found in the
postcentral gyrus
Neurons in this
cortical area
receive info from
sensory neurons
in the skin and
from
proprioceptors
which monitor
joint position
Contralateral
165

167. 167

168. 

Found posterior to
the primary
somatosensory
cortex and is
neurally tied to it
Synthesizes
multiple sensory
inputs to create a
complete
comprehension of
the object being
felt.
168

169. 

Gustatory cortex
is involved in
taste and is in the
parietal lobe just
deep to the
temporal lobe
Vestibular cortex
is involved in
balance and
equilibrium and
it is in the
posterior insula
169

170. 




The main part of the occipital lobe is found on
the medial surface only 2 small part of it
appears on the lateral surface.
post –calcarine sulcus: may extend on the
lateral surface and crrying a part of the center
of vision with it.
Sulcus lunatus:
Curved sulcus
Surrounds the posterior end of the postcalcarine sulcus.

171. 


Found in
the
posterior
and
medial
occipital
lobe
Largest
of the
sensory
cortices
Contralat
eral
171

172. 


Surrounds the primary
visual cortex
Basically vision is the
sensation of bars of
light on our retinal
cells. The primary
visual cortex tells
which cells are being
stimulated and how.
The association area
lets us “see” what
we’re looking at.
172

173. 
sulci of the temporal lobe:
 superior temporal sulcus:

runs parallel to the posterior ramus
of lateral sulcus and about one
finger’s breadth below it.
 inferior temporal sulcus

runs parallel to the superior
temporal sulcus and about one
finger’s breadth below it.

174. 





Auditory association area: surrounds the
auditory sensory area and occupies most of the
rest of superior temporal gyrus.
Responsible for knowing the meaning of the
sounds.
Inferior surface
The inferior surface of the brain is divided by
the stem of the lateral sulcus in to:
orbital surface_____rests on the orbit.
Tentorial surface ________ rests on the
tentorium cderebelli

175. 


Found in the superior
margin of the temporal
lobe, next to the lateral
sulcus
Sound waves excite
cochlear receptors in the
inner ear which send info
to the auditory cortex
There is also an auditory
association area which
lets us interpret and
remember sounds
175

176. 

between the superior temporal sulcus and posterior
ramub s of lateral sulcus.



Inferior temporal gyrus:
Below the inferior temporaral sulcus.
important areas of the temporarl lobe.


Middle temporal gyrus:
Between the superior and inferior temporal sulci


superior temporal gyrus:
The center of hearing (Heschl’s grus):
Found in the middle of the superior temporaral gyrus.

177. 
sulci of the oribital surface


The oldfactory bulb and tract lie in it.



olfactory sulcus: is straight deep sulcus parallel to
medial border.
Oribital sulci:
H-shaped sulcus on the lateral side of the
olfactory sulcus.
b. gyri of the oribital surface:

178. 





gyrus rectus: between the oldfactory sulcus and the
medial border.
oribital gyri:
Anterior: anterior to the oribital sulcus
Posterior: posterior to the oribital sulcus.
Medial: medial the oribital sulcus.
Lateral___lateral to the oribital sulcus

179. 



.
The sulci and gyri of the tentorial surface will
be studied with the medial surface.
Medial surface
sulci of medial and tentorial surface:


Callosal sulcus:
Lies above the corpus callosum

180. 


Is the continuation of the callosal sulcus on the
tentorial surface.
Ends in the uncus.



Hippocampal sulcus:
Sulcus cinguli:
Parallel to the callosal sulcus and about one
finger’s breadth above it.
Its posterior and curves upwards to end on the
superomedial border just behind the upper
end of the central sulcus.

181. 

Its upper end lies on the medial surface just in
front of the upturned part of the sulcus cinguli.



Central sulcus
Calcarine sulcus:
begins on the tentorial surface below the
splenium of corpus callosum.
Passes upwards and backwards on to the
medial surface of the occipital lobe where it
joins the paretoccipital sulcus

182. 
The change of name is due to the fact that the two parts
develop independently
 Post-calcarine sulcus:


Runs downwards and backwards to end the medial
surface near the occipital pole.
May curve round the occipital pole to end on the
superolateral surface.
 parieto-ocipital sulcus


Extends from the end of the calcarine sulcus upwards.
Cuts the supero-medial border one and half inches
above the occipital pole.

183. 


Collateral sulcus.
Is the best marked sulcus on the tentorial surface.
Extends from the occipital pole to the temporal pole.
 Occipito-temporal sulcus


Parallel with the collateral sulcus and about on inch
lateral to it.
the gyri of the medial and tentorial surfaces:
 The cuneus: is the triangular area bounded by the post-calcarine
sulcus, parieto-occipital sulcus and the supero-medial border.
Importance; contains part of the visual are.

184.  pre- Cuneus:

guadrate area between the parieto-occipital sulcus and
the upturned part of the sulcus cinguli.
 Lingual gyrus:



Looks- like the tongue.
Lies below the calcarine and post-calcarine sulci.
Importance; contains a great part of the visual area.
 gyrus cinguli


Lies between the callosal sulcus and the sulcus cinguli
Sometimes called parahippocampal gyrus.

185. 

Concerned with the olfactory sense.
May contain the center for the sense of taste.
 Isthmus of gyrus cinguli:


Narrow strip between the splenium and the
anterior part of calacarine sulcus.
It connects the hippocample gyrus and gyrus
cinguli.

186. lateral occipito-temporal gyrus:

lies on the lateral side of the occipito-temporal sulcus.
Miedal occipitio-temporal gyrus




Medial to the occipito-temporal sulcus between it and
the collateral sulcus.
Important areas on the medial and tentorial surfaces:
Center for sight (vision)
lies below the calcarine sulcus and above and below
the post-calcarine and around its end.

187. Visual association area:
Surrounds the visual area.
Responsible for knowing the meaning of the
pictures seen.
Hippocampal gyrus:





concerned with the olfactory sese but may contain
the center for the sense of taste.

188. 

1.
2.
3.
4.
Allows for analysis of sensory input.
Multiple inputs and outputs
Prefrontal cortex
Language areas
General interpretation area
Visceral association area
188

189. Prefrontal
Cortex



Anterior frontal
lobes
Involved in
analysis,
cognition, thinkin
g, personality, &
much more.
Look at its
evolution
189

190. Large area for language
understanding and
production surrounding
the lateral sulcus in the
left (language-dominant)
hemisphere
 Includes:
- Wernicke’s area 
understanding oral or
written words
- Broca’s area  speech production

190

191. 
General area integrates
multiple stimuli into a single
logical “understanding of the
situation.”
Found on only one
hemisphere – typically
left.
 Contained by 3 lobes:
temporal, occipital, and
parietal.


Visceral association area is
involved in perception of
visceral sensations (such as
digest).

Located in insular cortex
191

192. Lateralization




The fact that certain activities are the
almost exclusive domain of one of the 2
hemispheres
In most people, the left hemisphere has
a more control over language, math, and
logic
While the right hemisphere is geared
towards musical, artistic and other
creative endeavors
Most individuals with left cerebral
192

193. 193

194. 






Anterior Cereberal Artery
Origin: from internal carotid.
Course
passes foerwaeds and medially towards the middle
line.
Turns upwards to reach the genu of corpus callosum.
Runs backwares along the upper surface of corpus
callosum till the splenium.
Ends by turning upwards anterior to the parietooccipital sulcus

195. 1. Central branches
 Several slender twigs that pierce the surface of
the brain in front of the optic chiasma.
 Supplies.
 Anterior part of corpus striatum
 Anterior limb of internal capsule
2. Cortical branches:



Medial part of oribital surface
Medial surface except the occipital lobe
Upper inch of the lateral surface except the
occipital lobe

196. 3. Callosal branches:

To all parts of the corpus callosum except the
splenium

Important regions supplied by the anterior
cerebral artery

Motor and sensory areas of the lowerlimb in
the paracentral lobule on the medial surface.

Corpus callosum.

197. 


Effect of lesion in anterior cerebral artery:
paralysis and loss of sensation of the lower
limb.
Apraxia results from a lesion of corpus
callosum. Apraxia is the inability of the person
to do a purposeful movements although the
muscles concerned with these movements are
not paralysed.

198. 



Origin: from the internal carotid
Course:
Runs laterally in the stem of the lateral sulcus.
Terminates on the insula by dividing in to
several branches on the lateral surface.

200. 1. centeral branches:
 Small numerous arteries that pass through the anterior
perforated substance to the interior
 Called striate arteries because they are spent chiefly in
supplying the corups striatum and internal capsule
 They are classified in to medial and lateral groups
according to their relation to the lentiform nucleus.
 One large branch of these arteries is called the artery of
cerebral haemorrhage.

201. 2. Cortical branches: supply






Lateral part of oribital surface
Superolateral surface except.
Upper inch (anterior cerebral).
Occipital lobe (post cerebral)
Importance areas supplied by middle cerebral:
Motor and sensory areas of the whole body except the
lower limb which is supplied by the anterior cerebral
artery
Centre of hearing
Genu and posterior limb of the internal capsule.

202. 



Posterior Cerebral Artery
Origin: one of the two terminal branches of the
basilar artery.
Course: curves laterally and backwards round
the midbrain towards the occipital pole.
Enters the calcarine sulcus where it divides in
to two terminal branches which run onwards in
the postcalcarine and parieto-occipital sulci.

203. 1. Central branches; two groups.


Medial group: pierce the posterior perforated substance.
Lateral group: pierce the side of the midbrain. They supply the
thalamus and the midbrain.
2. Cortical branches: supplies.



Tentorial surface except the temporal pole
Lower inch of the superolateral surface.
Occipital lobe.
3. Posterior choroids artery
 artery on the side of midbrain.
 Passes inside the brain to supply the choroids plexus of
the third and lateral ventricles.

204. 



The centre of vision in the occipital lobe.
The centre of smell in the uncus.
Thalamus and midbrain.
Most of the choroids plexus of third & lateral
ventricles

206. Where’s the
insula?
What’s the name of
this region
What’s this
called?

208. 
How do you remember which
nerve is which number?

Here is a G-rated mnemonic
devices:
 Old Opie occasionally tries
trigonometry and feels very
gloomy, vague, and hypoactive.


There are also several R-rated
ones
Some cranial nerves are
sensory, some motor, and some
are both (mixed).

210. 




How many
noses do you
have?
Sensory, motor,
or mixed?
Run from the
nasal mucosa to
the olfactory
bulb.
Extend thru the
cribriform plate.
Lesion to these
nerves or
cribriform plate
fracture may
yield anosmia –
loss of smell.

211. 




How many eyes do
you have?
Sensory, motor, or
mixed?
Begin at the
retina, run to the
optic chiasm, cross
over, continue as
the optic tract and
synapse in the
thalamus.
Optic nerve
damage yields
blindness in the eye
served by the
nerve. Optic tract
damage yields
partial visual loss.
Visual defects =
anopsias

212. 



―Eye mover‖
Sensory, motor, or
mixed?
Originate at the
ventral midbrain.
Synapse on:

Extraocular muscles
 Inferior oblique;
Inferior, medial, and
superior rectus



Iris constrictor
muscle
Ciliary muscle
Disorders can
result in eye
paralysis, diplopia
or ptosis.

214. 



Controls the superior
oblique muscle which
depresses the eye via
pulling on the
superior oblique
tendon which loops
over a ligamentous
pulley known as the
trochlea.
Originates on the
dorsal midbrain and
synapses on the
superior oblique
Sensory, motor, or
mixed?
Trauma can result in
double vision.

216. CN5
Trigeminal Nerves



Sensory, motor, or
mixed?
Biggest cranial nerve
Originates in the pons
and eventually splits
into 3 divisions:



Ophthalmic (V1),
Maxillary (V2), &
Mandibular (V3).
Sensory info (touch,
temp., and pain) from
face.
Motor info to muscles of

218. 

Sensory, motor, or
mixed?
Runs between inferior
pons and lateral
rectus.
CN5
Abducens Nerves

220. 





Sensory, motor, or mixed?
Originates at the pons
Convey motor impulses to facial
skeletal muscles – except for
chewing muscles.
Convey parasympathetic motor
impulses to tear, nasal, and some
salivary glands.
Convey sensory info from taste
buds on anterior 2/3 of the tongue.
Facial nerve damage may yield
Bell’s palsy, total ipsilateral
hemifacial paralysis

222. 


Sensory, motor, or
mixed?
Originates at the pons
2 divisions:

Cochlear
 Afferent fibers from
cochlea in the inner ear
 HEARING

Vestibular
 Afferent fibers from
equilibrium receptors in
inner ear
 BALANCE

Functional impairment?

223. 


Sensory, motor, or mixed?
Fibers run emerge from
medulla and run to the
throat.
Motor Functions:
Motor fibers to some
swallowing muscles
 Parasympathetic fibers to
some salivary glands
Sensory Functions:


Taste, touch, heat from
pharynx and posterior tongue.
 Info from chemoreceptors on
the level of O2 and CO2 in the
blood. Info from baroreceptors
on BP.
 Chemoreceptors and
baroreceptors are located in
the carotid sinus – a dilation
in the internal carotid
artery.


224. 

Sensory, motor, or mixed?
Only cranial nerves to
extend beyond head and
neck.


Motor Functions:


Fibers emerge from
medulla, leave the skull, and
course downwards into the
thorax and abdomen.
Parasympathetic efferents to
the heart, lungs, and
abdominal organs.
Sensory Functions:

Input from thoracic and
abdominal viscera; from baroand chemoreceptors in the
carotid sinus; from taste buds
in posterior tongue and
pharynx

225. 

Sensory, motor, or
mixed?
Formed by the union of a
cranial root and a spinal
root.



CR arises from medulla
while SR arises from
superior spinal cord. SR
passes thru the FM and
joins with CR to form the
accessory nerve. They then
leave the skull via the
jugular foramen.
Cranial division then joins
vagus and innervates
larynx, pharynx, and soft
palate.
Spinal division innervates
sternocleidomastoids and
trapezius.

226. 


Sensory, motor, or
mixed?
Arise from the medulla
and exit the skull via the
hypoglossal canal and
innervate the tongue.
Innervate the intrinsic &
extrinsic muscles of the
tongue.


Swallowing, speech, food
manipulation.
Damage?