section 3, chapter 11
Development of the Brain &
Anatomy of the Cerebrum
The brain has many functions.
sensations and perceptions
commands skeletal muscles
regulates visceral activities
The major parts of the brain:
Figure 11.15b. Sagittal section of human brain.
The major portions include the cerebrum, the diencephalon, the cerebellum,
and the brainstem. The brainstem includes the midbrain, the pons, and the
The central nervous system develops from a neural tube
that gives rise to the brain and spinal cord.
The brain begins as three primary vesicles
1.prosencephalon – forebrain
2.mesencephalon – midbrain
3.rhombencephalon – hindbrain
Later the brain divides into five secondary vesicles
The prosencephalon divides into the
telencephalon & diencephalon.
The mesencephalon remains as the midbrain.
The rhombencephalon divides into the
metencephalon & myelencephalon
Five secondary vesicles:
Eventually the vesicles give rise to regions of the brain:
telencephalon gives rise to the cerebrum and basal nuclei
diencephalon gives rise to the thalamus, hypothalamus, and pituitary gland
mesencephalon becomes the midbrain
metencephalon forms the pons and cerebellum
myelencephalon forms the medulla oblongata.
functions of the cerebrum
The cerebrum provides higher brain functions:
2.Voluntary muscle movements
Colors distinguish the lobes of the cerebral hemisphere.
(a) lateral view. (b) superior view
anatomy of the cerebrum
The cerebrum consists of a left and right
hemisphere separated by a longitudinal fissure.
A bridge of nerve fibers called the cporus
callosum connects the two cerebral hemispheres.
A transverse fissure separates the cerebrum from the cerebellum.
The surface of the cerebrum contains many ridges and grooves.
Gyri (sing. gyrus) = Bumps or convolutions
Sulci (sing. Sulcus)= Grooves in cerebrum
Lobes of the cerebrum
The cerebrum is divided into
five (5) lobes bilaterally:
Insula – deep lobe
Figure 11.16(c) lateral view of the cerebrum
using colors to distinguish the individual lobes.
The temporal lobe is retracted to expose the
Functional regions of the cerebral cortex
The cerebral cortex is a thin outer
layer of gray matter in the cerebrum.
• contains 75% of all neurons in
the nervous system
The cerebral medulla is a thick layer
of white matter underlying the cortex.
•bulk of cerebrum
•contains masses of gray matter
Functional regions of the cerebral cortex
Sensory Areas – cerebrum interprets impulses from receptors
Motor Areas – cerebrum controls voluntary motor actions
Association Areas - cerebrum connects from one region of the brain to
• Thoughts, emotions, and understanding
Functions of the frontal lobes
Association areas = prefrontal cortex
higher intellect: judgment, complex problem solving, planning,
and decision making
Motor areas = voluntary motor control
Frontal eye field – voluntary movements of eyes
Broca’s area – coordinates mouth, tongue, and pharynx for
• Damage may result in patient being unable to form complete
Primary motor cortex (precentral gyrus) – motor areas involved
with control of voluntary cells within the frontal lobe that
Pyramidal cells - muscles
initiate voluntary movements
Functions of the parietal lobes
Sensory areas of the parietal lobes
Post-central gyrus (primary somatosensory cortex)– sensory
areas involved with touch, temperature, pain and other cutaneous
Wernike’s Area – sensory speech area. Choosing words to express
thoughts and emotionsUsually within left hemisphere.
General interpretive area (Wernike’s area) - integrates visual,
auditory, and other sensory information an then interprets a
Figure 11.18. Functional regions of the cerebral cortex.
(a)motor areas that control voluntary muscles.
(b)sensory areas involved with cutaneous and other senses.
Functions of the temporal and occipital lobes
• Sensory Areas
• Hearing and smell (smell within deep temporal lobe)
•Association areas – interpret complex sensory experiences
• Understand speech and reading
• Stores memories of visual scenes, music, and other sensory patterns
•Visual Cortex - vision
Combines visual images with other experiences – face recognition
The left hemisphere is dominant in most individuals
The dominant hemisphere controls:
• Speech, reading and writing
• Analytical and computational
The non-dominant hemisphere controls:
• Motor tasks and other non-verbal
•Provides emotional and intuitive
Corpus callosum enables the dominant hemisphere to control the motor cortex in
the nondominant hemisphere. It also relays sensory information reaching the nondominant hemisphere to the dominant hemisphere to be interpreted.
The basal nuclei are three
masses of grey matter deep
within the cerebrum:
1. Caudate nucleus
3. Globus pallidus
The basal nuclei secrete the inhibitory neurotransmitter dopamine
• Basal nuclei interact with a region in the midbrain, called Substantia Nigra
• Basal nuclei & substantia nigra facilitate voluntary movements
Parkinson’s Disease (PD) results occurs from degeneration of the
basal nuclei and the substantia nigra. This results in a deficiency
• tremors at rest
• poor small muscle control
• difficulties speaking
End of section 3,
Figure 11D. Muhammad Ali has PD from many
years of head injuries as a boxer. Michael J.
Fox first experienced symptoms of PD at age 29,
which is unusual.