Download Nervous System Part Five

Nervous System
THE BRAIN CONT.
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
Grey matter
Brain Regions
4 Adult brain regions

1.
Cerebral hemispheres (cerebrum)
2.
Diencephalon
3.
4.
Cerebellum
Brain stem (midbrain, pons, and medulla)
Diencephalon
 Three paired structures
 Thalamus
 Hypothalamus
 Epithalamus
 Encloses the third ventricle
Cerebral hemisphere
Septum pellucidum
Interthalamic
adhesion
(intermediate
mass of
thalamus)
Interventricular
foramen
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Corpus callosum
Fornix
Choroid plexus
Thalamus
(encloses third
ventricle)
Posterior commissure
Pineal gland
(part of epithalamus)
Corpora
quadrigemina MidCerebral
brain
aqueduct
Arbor vitae (of
cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Spinal cord
Figure 12.12
Thalamus
 Several nuclei
 Gateway of the
cerebral cortex
 Major relay
station for
most sensory
impulses
Copyright 2009, John Wiley & Sons, Inc.
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
Hypothalamus
 Inferior to the thalamus
 Forms portions of walls of the third ventricle
 Consists of a number of nuclei
Copyright 2009, John Wiley & Sons, Inc.
Hypothalamus
 Infundibulum
 Mammillary bodies
 Responsible for most neurogenic homeostasis of
the body
Hypothalamus
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 (tactile sexual
reponse)
Hypothalamic Function
 Water balance and thirst
 Controls release of hormones by the anterior
pituitary and produces posterior pituitary hormones
 Regulation of sleep-wake cycles
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

2.
Cerebral hemispheres (cerebrum)
Diencephalon
3.
Brain stem (midbrain, pons, and medulla)
4.
Cerebellum
1.
The Brain Stem
 Supports most of basic life functions
 Pathway for fiber tracts
 Origin for most cranial nerves
Midbrain
 Associated with visual and auditory reflexes
 Pupillary reflex
 Cranial nerves III and IV
 Red Nucleus—descending motor pathways
involved in voluntary movement
Frontal lobe
Olfactory bulb
(synapse point of
cranial nerve I)
Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Midbrain
Pons
Temporal lobe
Medulla
oblongata
Cerebellum
Spinal cord
Figure 12.14
View (a)
Optic chiasma
Optic nerve (II)
Crus cerebri of
cerebral peduncles
(midbrain)
Diencephalon
• Thalamus
• Hypothalamus
Mammillary body
Thalamus
Hypothalamus
Diencephalon
Midbrain
Oculomotor nerve (III)
Trochlear nerve (IV)
Pons
Brainstem
Medulla
oblongata
Trigeminal nerve (V)
Pons
Facial nerve (VII)
Middle cerebellar
peduncle
Abducens nerve (VI)
Vestibulocochlear
nerve (VIII)
Pyramid
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Vagus nerve (X)
Ventral root of first
cervical nerve
Decussation of pyramids
Accessory nerve (XI)
Spinal cord
(a) Ventral view
Figure 12.15a
Crus cerebri of
cerebral peduncles
(midbrain)
Thalamus
View (b)
Infundibulum
Pituitary gland
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Trigeminal nerve (V)
Pons
Superior cerebellar peduncle
Middle cerebellar peduncle
Facial nerve (VII)
Abducens nerve (VI)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
Thalamus
Vagus nerve (X)
Hypothalamus
Diencephalon
Midbrain
Accessory nerve (XI)
Pons
Brainstem
Medulla
oblongata
(b) Left lateral view
Figure 12.15b
Pons
 Bridge between midbrain and medulla oblongata
 Connects cerebellum to cerebrum and spinal cord
 Cranial nerves: V- VIII (vestibular branch)
Crus cerebri of
cerebral peduncles
(midbrain)
Thalamus
View (b)
Infundibulum
Pituitary gland
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Trigeminal nerve (V)
Pons
Superior cerebellar peduncle
Middle cerebellar peduncle
Facial nerve (VII)
Abducens nerve (VI)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
Thalamus
Vagus nerve (X)
Hypothalamus
Diencephalon
Midbrain
Accessory nerve (XI)
Pons
Brainstem
Medulla
oblongata
(b) Left lateral view
Figure 12.15b
Medulla
 Continuous with spinal cord
 Passage of motor and sensory impulses between brain and
spinal cord
 Decussation of tracts in pyramids
Longitudinal fissure
Lateral
ventricle
Superior
Commissural
fibers (corpus
callosum)
Association
fibers
Basal nuclei
• Caudate
• Putamen
• Globus
pallidus
Corona radiata
Thalamus
Internal
capsule
Fornix
Gray matter
Third
ventricle
White matter
Pons
Projection
fibers
Medulla oblongata
(a)
Decussation
of pyramids
Figure 12.10a
Medulla: Vital Centers
 Cardiac
 Vasomotor
 Respiratory
 Swallowing
 Vomiting
 Cranial nerves: VIII (cochlear branch) -XII
Brain Regions
4 Adult brain regions

3.
Cerebral hemispheres (cerebrum)
Diencephalon
Brain stem (midbrain, pons, and medulla)
4.
Cerebellum
1.
2.
The Cerebellum
 Dorsal to the pons and medulla
 Subconsciously provides precise timing and
appropriate patterns of skeletal muscle contraction
 Contains both white and gray matter
Anterior lobe
Cerebellar cortex
Arbor
vitae
Cerebellar
peduncles
• Superior
• Middle
• Inferior
Medulla
oblongata
(b)
Flocculonodular
lobe
Posterior
lobe
Choroid
plexus of
fourth
ventricle
Figure 12.17b
Cerebellar Functions
 Proprioception
 Prime mover inhibition and antagonist activation
 Dysmetria
 Progression
 Dysarthria
Functional Brain Systems
 Networks of neurons that work together and span
wide areas of the brain


Limbic system
Reticular formation
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
Septum pellucidum
Diencephalic structures
of the limbic system
•Anterior thalamic
nuclei (flanking
3rd ventricle)
•Hypothalamus
•Mammillary
body
Olfactory bulb
Corpus callosum
Fiber tracts
connecting limbic
system structures
•Fornix
•Anterior commissure
Cerebral structures of the
limbic system
•Cingulate gyrus
•Septal nuclei
•Amygdala
•Hippocampus
•Dentate gyrus
•Parahippocampal
gyrus
Figure 12.18
Limbic System
 Emotional brain
 Recognizes angry or fearful facial expressions, assesses danger,
and 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
Reticular Formation
 Broad columns of nuclei along the length of the brain
stem
 Far-flung axonal connections with hypothalamus,
thalamus, cerebral cortex, cerebellum, and spinal
cord
Radiations
to cerebral
cortex
Visual
impulses
Auditory
impulses
Reticular formation
Ascending general
sensory tracts
(touch, pain, temperature)
Descending
motor projections
to spinal cord
Figure 12.19
Four Functions of 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
Questions?