Download Brain Internal Structure (2)

Objectives
 Describe the types of fibers in the internal capsule.
 Identify the basal ganglia nuclei.
 Identify main parts of the diencephalons and
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name the main functions of each part
Briefly describe the brain ventricles and
meanings.
Describe the organization of the cerebral cortex.
(Layers and columnar organization).
Locate the motor, sensory and other cortical
areas.
Describe the cortical areas related to the written
and spoken language.
Identify the structures in coronal, sagittal and
horizontal sections of brain.
 Internal capsule
(anterior limb, genu,
posterior limb).
 It is medial to lentiform
nucleus and lateral to
the thalamus and
cuadate nucleus.
 It contains projection
fibers.
 Internal capsule
(anterior limb, genu,
posterior limb).
 It is medial to lentiform
nucleus and lateral to
the thalamus and
cuadate nucleus.
 It contains projection
fibers.
 Basal ganglia are
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masses of gray matter
situated deep within
each cerebral
hemisphere.
They are:
Corpus striatum.
Amygdaloid nucleus.
Claustrum.
Corpus striatum is
divided by internal
capsule, into caudate
nucleus and
lentiform nucleus(
putamen & globus
pallidus).
 Diencephalon
 The diencephalon
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consists of the
third ventricle and
the structures that
form its
boundaries .
It is divided into:
Thalamus.
Subthalamus.
Hypothalmus.
Epithalamus.
 Ventricular System:
 The ventricles are four
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cerebrospinal fluid-filled
cavities located within the
brain.
Two lateral ventricles.
Third ventricle.
Fourth ventricle.
Lateral ventricles
communicate through
interventricular foramina
(of Monro) with third
ventricle.
The third is connected to
the fourth by cerebral
aqueduct (of Sylvius).
 Meninges:
 Brain and spinal cord are
surrounded by three
membranes (meninges).
 Dura mater.
 Arachnoid mater.
 Pia mater.
 Cortical layers:
 Molecular layer (plexiform
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layer).
External granular layer.
External pyramidal layer.
Internal granular layer.
Internal pyramidal
(ganglionic ) layer.
Multiform layer (layer of
polymorphic cells).
Columnar organization:
Cortex is organized into
vertical columns of
functional activity which
extends from the cortical
surface to the white matter.
Each column possesses
afferent fibers, internuncial
neurons, and efferent fibers.
 Cortical areas
 Frontal lobe:
 Precentral area includes
precentral gyrus, posterior
parts of superior, middle,
inferior frontal gyri and
paracentral lobule.
 Motor area( primary motor
area, or Brodmann area 4)
occupies posterior part of
precentral gyrus and
paracentral lobule.
 Premotor area (secondary
motor area, or Brodmann
area 6 ,8, 44, and 45)
occupies the anterior part
of precentral gyrus and
posterior parts of superior,
middle, and inferior frontal
gyri.
 Supplementary motor area is
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anterior to paracentral lobule.
Frontal eye field extends from
the facial area of precentral
gyrus into middle frontal gyrus
(parts of Brodmann areas 6, 8,
and 9).
Motor speech area of Broca is
located in the inferior frontal
gyrus.
Prefrontal cortex lies anterior
to the precentral area. It
includes greater parts of
superior, middle, and inferior
frontal gyri, orbital gyri, most
of medial frontal gyrus, and
anterior half of cingulate gyrus
(Brodmann areas 9, 10, 11, and
12).
Movement areas of the body
are represented in inverted
form in the precentral gyrus.
 Parietal lobe:
 Primary somesthetic area (primary somatic sensory cortex)
occupies postcentral gyrus and posterior part of paracentral
lobule (Brodmann areas 3, 1, and 2).
 Secondary somesthetic area (secondary somatic sensory cortex ) is
in superior part of lateral fissure.
 Somesthetic association area occupies superior parietal lobule
and extending onto medial surface (Brodmann areas 5 and 7).
 Occipital lobe
 Primary visual area (Brodmann area 17) is situated in walls of
posterior part of calcarine sulcus and around occipital pole
onto the lateral surface.
 Secondary visual area (Brodmann areas 18 and 19) surrounds
the primary visual area.
 Occipital eye field exists in secondary visual area.
 Temporal lobe:
 Primary auditory area (Brodmann areas 41,42) includes the gyrus
of Heschl is situated in inferior wall of the lateral sulcus.
 Secondary auditory area ( association) is posterior to primary area
and in superior temporal gyrus (Brodmann area 22).
 Sensory speech area of Wernicke is in dominant hemisphere,
mainly in superior temporal gyrus, with extensions into the
parietal region.
 Wernicke area is connected to Broca area by arcuate fasciculus.
 Other cortical areas:
 Taste & smell area
(gustatory) is in lower end
of postcentral gyrus in the
insula.
 Vestibular area lies opposite
auditory area in the
superior temporal gyrus.
 Primary sensory and
primary motor areas form
only a small part of cortical
surface area. Remaining
areas are association areas
which concerned with
behavior, discrimination,
and interpretation of
sensory experiences.
Brain sections