Review
White versus grey matter
Ventricles
4 brain regions
4 lobes of cerebral hemispheres
3 layers of cerebrum
Cortex
Motor
Sensory
Association
White matter tracts
Gray matter
Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum)
2. Diencephalon 3. Cerebellum
4. Brain stem (midbrain, pons, and medulla)
Figure 12.12
Corpus callosum
Choroid plexus Thalamus
(encloses third
ventricle)
Pineal gland
(part of epithalamus)
Posterior commissure
Corpora
quadrigemina Cerebral aqueduct Arbor vitae (of cerebellum)
Fourth ventricle Choroid plexus Cerebellum
Septum pellucidum
Interthalamic
adhesion
(intermediate
mass of
thalamus) Interven-
tricular
foramen
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Cerebral hemisphere
Mammillary body Pons
Medulla oblongata
Spinal cord
Mid-
brain
Fornix
Diencephalon
Thalamus
Several nuclei
Gateway of the cerebral cortex
Major relay station for most
sensory impulses
Diencephalon
Thalamus
Relay center for cerebral activation
Associated with reticular formation
Relay center for somatosensory information
Except olfaction
Coma is associated with thalamic injury
Vegetative state = damage to cortical pathways
Refer to diagram on CNS 8
Diencephalon
Hypothalamus
Inferior to the thalamus
Forms portions of walls of the third ventricle
Consists of a number of nuclei
Diencephalon
Hypothalamus Infundibulum
Mammillary bodies
Responsible for most neurogenic homeostasis of the body
Diencephalon
Hypothalamic function
Autonomic control center for many visceral functions
Examples
Blood pressure, rate and force of heartbeat
Regulates body temperature
Hunger and G.I tract regulation
Center for emotional response
Example
Tactile sexual response
Diencephalon
Hypothalamic Function
Water balance and thirst
Controls release of hormones by the anterior pituitary and produces posterior pituitary hormones
Regulation of sleep-wake cycles
Diencephalon
Epithalamus
Forms roof of third ventricle
Pineal gland, choroid plexus
Melatonin
We’ll discuss it’s endocrine function later….
Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum)
2. Diencephalon
3. Brain stem (midbrain, pons and medulla) 4. Cerebellum
The Brain Stem
Functions
Supports most of basic life functions
Pathway for fiber tracts
Origin for most cranial nerves
The Brain Stem
Midbrain
Associated with visual and auditory reflexes
Pupillary reflex
Cranial nerves III and IV
Red nucleus
Descending motor pathways involved in voluntary movement
Figure 12.14
Frontal lobe
Olfactory bulb
(synapse point of
cranial nerve I) Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Pons
Medulla
oblongata
Cerebellum
Temporal lobe
Spinal cord
Midbrain
Figure 12.15a
Optic chiasma View (a)
Optic nerve (II)
Mammillary body
Oculomotor nerve (III)
Crus cerebri of
cerebral peduncles
(midbrain)
Trigeminal nerve (V)
Abducens nerve (VI) Facial nerve (VII)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Ventral root of first
cervical nerve
Trochlear nerve (IV)
Pons Middle cerebellar peduncle
Pyramid
Decussation of pyramids
(a) Ventral view
Spinal cord
Vestibulocochlear
nerve (VIII)
Glossopharyngeal nerve (IX)
Diencephalon
• Thalamus • Hypothalamus
Diencephalon
Brainstem
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Figure 12.15b
View (b)
Crus cerebri of
cerebral peduncles
(midbrain)
Infundibulum
Pituitary gland
Trigeminal nerve (V)
Abducens nerve (VI)
Facial nerve (VII)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Pons
(b) Left lateral view
Glossopharyngeal nerve (IX)
Diencephalon
Brainstem
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Thalamus
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
The Brain Stem
Pons
Bridge between midbrain and medulla oblongata
Connects cerebellum to cerebrum and spinal cord
Cranial nerves V- VIII (vestibular branch)
Figure 12.15b
View (b)
Crus cerebri of
cerebral peduncles
(midbrain)
Infundibulum
Pituitary gland
Trigeminal nerve (V)
Abducens nerve (VI)
Facial nerve (VII)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Pons
(b) Left lateral view
Glossopharyngeal nerve (IX)
Diencephalon
Brainstem
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Thalamus
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
The Brain Stem
Medulla
Continuous with spinal cord
Passage of motor & sensory impulses between brain & spinal cord
Decussation of tracts in pyramids
Figure 12.10a
Corona radiata
Projection
fibers
Longitudinal fissure
Gray matter
White matter
Association
fibers
Lateral
ventricle
Fornix
Third
ventricle
Thalamus
Pons
Medulla oblongata Decussation
of pyramids
Commissural
fibers (corpus
callosum)
Internal
capsule
Superior
Basal nuclei
• Caudate
• Putamen
• Globus
pallidus
(a)
The Brain Center
Medulla
Vital centers
Cardiac
Vasomotor
Respiratory
Swallowing
Vomiting
Cranial nerves VIII (cochlear branch) -XII
Brain Regions
4 Adult brain regions 1. Cerebral hemispheres (cerebrum)
2. Diencephalon
3. Brain stem (midbrain, pons, and medulla)
4. Cerebellum
The Cerebellum
Dorsal to the pons & medulla
Subconsciously provides precise timing & appropriate patterns of skeletal muscle contraction
Contains both white & gray matter
Figure 12.17b
(b)
Medulla
oblongata Flocculonodular
lobe
Choroid
plexus of
fourth
ventricle
Posterior
lobe
Arbor
vitae
Cerebellar cortex
Anterior lobe
Cerebellar
peduncles • Superior • Middle • Inferior
The Cerebellum
Functions
Proprioception
Prime mover inhibition and antagonist activation
Dysmetria
Progression
Dysarthria
Functional Brain Systems
Networks of neurons that work together & span wide areas of the brain
Limbic system
Reticular formation
Functional Brain Systems
Limbic system
Structures on the medial aspects of cerebral hemispheres and diencephalon
Includes parts of the diencephalon and some cerebral structures that encircle the brain stem
Figure 12.18
Corpus callosum
Septum pellucidum
Olfactory bulb
Diencephalic structures
of the limbic system
•Anterior thalamic nuclei (flanking 3rd ventricle)
•Hypothalamus •Mammillary
body
Fiber tracts
connecting limbic system structures
•Fornix •Anterior commissure
Cerebral struc-
tures of the limbic system
•Cingulate gyrus •Septal nuclei •Amygdala •Hippocampus •Dentate gyrus •Parahippocampal gyrus
Functional Brain Systems
Limbic system Emotional brain
Recognizes angry or fearful facial expressions
Assesses danger & elicits the fear response
Plays a role in expressing emotions via gestures and resolves mental conflict
Connection to pre-frontal cortex allows us to “count to ten”
Puts emotional responses to odors
Example: skunks = smell bad
Functional Brain Systems
Reticular formation
Broad columns of nuclei along the length of the brain stem
Far-flung axonal connections with hypothalamus, thalamus, cerebral cortex, cerebellum & spinal cord
Figure 12.19
Visual impulses
Reticular formation
Ascending general sensory tracts (touch, pain, temperature)
Descending motor projections to spinal cord
Auditory impulses
Radiations to cerebral cortex
Functional Brain Systems
Functions of the reticular formation
1. Somatic motor control
Reticulospinal tract = improves smoothness of movement
2. Autonomic control
Respiratory and cardiovascular centers
3. Arousal
RAS = filter
4. Pain modulation
Can block pain transmission