Download Lecture 5 - Brain I - Linn

4/9/2010
Objectives
To orient the student to the major regions of the
brain.
To briefly identify the functional roles of each
lobe of the cerebrum.
To outline the regions of
cerebral motor activity & sensory activity.
To define the association areas of the brain and
provide an example.
To address the phenomena of lateralization.
To explain the association between white matter
and basal nuclei.
Cerebral
hemisphere
Diencephalon
Cerebellum
Brain stem
• Midbrain
• Pons
• Medulla
oblongata
(d) Birth
Figure 12.3d
Regions and Organization
of the CNS
I. Adult brain regions
1.
2.
3.
4.
Cerebral hemispheres
Diencephalon
Brain stem (midbrain, pons, and medulla)
Cerebellum
II. Spinal Cord
1. Central cavity surrounded by a gray matter core.
2. Fiber tracts - external white matter/myelin.
Ventricles
A lumen/spacelumen/space- derived from the neural tube
Filled with spinal fluids.
> Lateral
>Third ventricle
>Fourth ventricle.
Cerebrum
Septum
pellucidum
Lateral ventricle
Anterior horn
Inferior
horn
Interventricular
foramen
Third ventricle
Cerebral aqueduct
Lateral
aperture
Fourth ventricle
Central canal
Most superior part of the brain.
83% of the brain mass
Divided into two hemispheres.
….connected by the longitudinal fissure.
Cerebral cortex – gray matter
Contralateral control - opposite side of the
body
(a) Anterior view
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Anterior
Tour of the Brain - CNS
Cerebrum - Responsible for consciousness. Divided
into hemispheres & association areas.
Controls: conscious mind, communication, memory
and understanding, voluntary movements, creativity.
Composed of primarily gray matter i.e. numerous cell
bodies of neurons.
- Convolutions called gyri
- Grooves are called sulci
- Deep grooves are called fissures
fissures..
Longitudinal
fissure
Frontal lobe
Figure 12.6c Lobes and
Parietal
fissures of the cerebral
lobe
hemispheres.
Cerebral veins
and arteries
covered by
arachnoid
mater
Right cerebral
hemisphere
Occipital
lobe
Left cerebral
hemisphere
Posterior
(c)
Lobes of the Brain
>
>
>
>
Frontal
Parietal
Temporal Lobe
Occipital
Frontal
lobe
Central
sulcus
Parietal lobe
Figure 12.6a Lobes and
fissures of the cerebral
hemispheres.
Occipital lobe
Temporal lobe
Fissure
(a deep
sulcus)
Gyrus
Cortex (gray matter)
Sulcus
White matter
(a)
Cerebral Motor Activity
I. Primary (somatic) motor cortex – conscious motor
control. Stroke paralyzes the body muscles controlled
by those areas.
II. Premotor cortex - Learned motor skills of a repetitious
or patterned nature e.g. typing
Primary motor cortex
Premotor cortex
Frontal eye field
Broca’s area
(outlined by dashes)
IV. Frontal eye field –voluntary eye movement
Primary somatosensory
cortex
Somatosensory
association cortex
Somatic
sensation
Figure 12.8a Functional
and structural areas of
the cerebral cortex.
Prefrontal cor tex
Working memory
for spatial tasks
Solving complex,
multitask problems
III. Broca’s area – associated with language and sound
Central sulcus
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Vision
Hearing
(a) Lateral view, left cerebral hemisphere
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Posterior
The motor
homonculus
Motor
The sensory
homonculus
Sensory
Anterior
Motor map in
precentral gyrus
Sensory map in
postcentral gyrus
Figure 12.9 Body maps
in the primary motor
cortex and
somatosensory cortex of
the cerebrum.
Toes
Genitals
Jaw
Tongue
Swallowing
Primary motor
cortex
(precentral gyrus)
Primary somatosensory cortex
(postcentral gyrus)
Intraabdominal
Association Areas
Regions of the brain that communicate i.e.
“associate
associate”” with primary regions of the brain.
Act with other sensory association areas
to analyze/interpret and act on sensory
inputs based on past experiences.
experiences.
Multiple inputs & multiple outputs i.e. complex
End
Sensory Activity of the Cerebrum
Primary somatosensory cortex
- Receives sensory
information from the
skin, skeletal muscles,
and joints
- spatial discrimination
Primary visual cortex
Primary auditory cortex
Cerebral Lateralization
Left – controls:
Speech, writing, reading and math
“Analytical and sequential”
Right – controls:
recognition of space, patterns, music and
emotion, nonnon-verbal language, “tone.”
“ Holistic and recognition”
White matter
Material responsible for communication
between cerebral cortex and lower CNS centers.
Composed of myelinated fibers bundled into
large tracts.
Commissures: fibers connecting gray areas of
Commissures:
the 2 hemisphere.
> Corpus callosum (largest)
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Basal nuclei
Associated with subthalamic nuclei (the floor of the
diencephalon).
Dienchephalon
Gray matter of the third ventricle
(located at the core of the forebrain)
Composed of distinctive cell groups: e.g. Caudate &
lentiform
Play a role in motor control, may be involved with attention
and cognition.
Disorders of the basal nuclei show up as too much or too
little movement such as Huntington’s or Parkinson’s
diseases.
I. Thalamus – relay station
II. Hypothalamus – homeostasis regulator
III. Epithalamus – pineal gland & choroid
plexus.
Brain Stem (intro)
Superior to Inferior –
> Midbrain – visual & auditory reflex centers & fear
> Pons – regulation of respiration
> Medulla Oblongata – respiratory rhythm & heart rate
Histology: similar to the spinal cord i.e. gray matter is deep
and white matter surrounds it.
Controls –
Automatic behaviors for survival
Heavily involved with the innervation of the head
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