1. THE CENTRAL NERVOUS SYSTEM: PART B12
THE CENTRAL NERVOUS SYSTEM: PART B

2. Lateralization of Cortical Function
Division of labor between hemispheres
Cerebral dominance
Designates the hemisphere dominant for language (left hemisphere in 90% of people)

3. Lateralization of Cortical Function
Left hemisphere
Controls language, math, and logic
Right hemisphere
Insight, visual-spatial skills, intuition, and artistic skills
Left and right hemispheres communicate via fiber tracts in the cerebral white matter

4. Cerebral White Matter Myelinated fibers and their tracts
Responsible for communication
Commissures (in corpus callosum)—connect gray matter of the two hemispheres
Association fibers—connect different parts of the same hemisphere
Projection fibers—(corona radiata) connect the hemispheres with lower brain or spinal cord

5. Commissural fibers (corpus Longitudinal fissure callosum) Superior
Lateral
ventricle
Association
fibers
Basal nuclei
• Caudate
Corona radiata
• Putamen
• Globus pallidus
Fornix
Internal
capsule
Thalamus
Gray matter
Third
ventricle
White matter
Projection
fibers
Pons
Decussation
of pyramids
Medulla oblongata
(a)
Figure 12.10a

6. Basal Nuclei (Ganglia)
Subcortical nuclei
Consists of the corpus striatum
Functionally associated diencephalon and the midbrain

7. Fibers of corona radiata Caudate nucleus Thalamus Lentiform Tail of
• Putamen
• Globus pallidus
(deep to putamen)
Tail of
caudate
nucleus
Corpus
striatum
Projection fibers
run deep to
lentiform nucleus
(a)
Figure 12.11a

8. Tail of caudate nucleus Third ventricle Inferior horn
Anterior
Cerebral cortex
Cerebral white matter
Corpus callosum
Anterior horn
of lateral ventricle
Caudate nucleus
Putamen
Globus
pallidus
Lentiform
nucleus
Thalamus
Tail of caudate nucleus
Third ventricle
Inferior horn
of lateral ventricle
(b)
Posterior
Figure 12.11b (1 of 2)

9. Cerebral cortex Cerebral white matter Corpus callosum Anterior horn
of lateral ventricle
Caudate nucleus
Lentiform nucleus
Thalamus
Third ventricle
Inferior horn
of lateral ventricle
(b)
Figure 12.11b (2 of 2)

10. Functions of Basal Nuclei
Though somewhat elusive, the following are thought to be functions of basal nuclei
Influence muscular control
Help regulate attention and cognition
Regulate intensity of slow or stereotyped movements
Inhibit antagonistic and unnecessary movements

11. Diencephalon Three paired structures Encloses the third ventricle
Thalamus
Hypothalamus
Epithalamus
Encloses the third ventricle
PLAY
Animation: Rotatable brain (sectioned)

12. Cerebral hemisphere Septum pellucidum Corpus callosum Interthalamic
adhesion
(intermediate
mass of
thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third
ventricle)
Interven-
tricular
foramen
Posterior commissure
Pineal gland
(part of epithalamus)
Anterior
commissure
Corpora
quadrigemina
Mid-
brain
Hypothalamus
Cerebral
aqueduct
Optic chiasma
Arbor vitae (of
cerebellum)
Pituitary gland
Fourth ventricle
Mammillary body
Choroid plexus
Pons
Cerebellum
Medulla oblongata
Spinal cord
Figure 12.12

13. Thalamus 80% of diencephalon
Superolateral walls of the third ventricle
Connected by the interthalamic adhesion (intermediate mass)
Contains several nuclei, named for their location
Nuclei project and receive fibers from the cerebral cortex

14. Dorsal nuclei Medial Lateral dorsal Lateral posterior Pulvinar
Anterior
nuclear
group
Medial
geniculate
body
Reticular
nucleus
Lateral
geniculate
body
Ventral
postero-
lateral
Ventral
anterior
Ventral
lateral
Ventral nuclei
(a) The main thalamic nuclei. (The reticular nuclei that “cap” the thalamus laterally are depicted as curving translucent structures.)
Figure 12.13a

15. Thalamic Function Gateway to the cerebral cortex
Sorts, edits, and relays information
Afferent impulses from all senses and all parts of the body
Impulses from the hypothalamus for regulation of emotion and visceral function
Impulses from the cerebellum and basal nuclei to help direct the motor cortices
Mediates sensation, motor activities, cortical arousal, learning, and memory

16. Hypothalamus Forms the inferolateral walls of the third ventricle
Contains many nuclei
Example: mammillary bodies
Paired anterior nuclei
Olfactory relay stations
Infundibulum—stalk that connects to the pituitary gland

17. Hypothalamic Function
Autonomic control center for many visceral functions (e.g., blood pressure, rate and force of heartbeat, digestive tract motility)
Center for emotional response: Involved in perception of pleasure, fear, and rage and in biological rhythms and drives

18. Hypothalamic Function
Regulates body temperature, food intake, water balance, and thirst
Regulates sleep and the sleep cycle
Controls release of hormones by the anterior pituitary
Produces posterior pituitary hormones

19. Epithalamus
Most dorsal portion of the diencephalon; forms roof of the third ventricle
Pineal gland—extends from the posterior border and secretes melatonin
Melatonin—helps regulate sleep-wake cycles

20. Cerebral hemisphere Septum pellucidum Corpus callosum Interthalamic
adhesion
(intermediate
mass of
thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third
ventricle)
Interven-
tricular
foramen
Posterior commissure
Pineal gland
(part of epithalamus)
Anterior
commissure
Corpora
quadrigemina
Mid-
brain
Hypothalamus
Cerebral
aqueduct
Optic chiasma
Arbor vitae (of
cerebellum)
Pituitary gland
Fourth ventricle
Mammillary body
Choroid plexus
Pons
Cerebellum
Medulla oblongata
Spinal cord
Figure 12.12

21. Brain Stem
Three regions
Midbrain
Pons
Medulla oblongata

22. Brain Stem
Similar structure to spinal cord but contains embedded nuclei
Controls automatic behaviors necessary for survival
Contains fiber tracts connecting higher and lower neural centers
Associated with 10 of the 12 pairs of cranial nerves

23. 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

24. Oculomotor nerve (III) Trochlear nerve (IV)
View (a)
Optic chiasma
Optic nerve (II)
Diencephalon
Crus cerebri of
cerebral peduncles
(midbrain)
• Thalamus
• Hypothalamus
Thalamus
Mammillary body
Diencephalon
Hypothalamus
Oculomotor nerve (III)
Midbrain
Pons
Brainstem
Trochlear nerve (IV)
Medulla
oblongata
Trigeminal nerve (V)
Middle cerebellar
peduncle
Pons
Facial nerve (VII)
Abducens nerve (VI)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Pyramid
Vagus nerve (X)
Ventral root of first
cervical nerve
Accessory nerve (XI)
Decussation of pyramids
Spinal cord
(a) Ventral view
Figure 12.15a

25. Superior cerebellar peduncle Pons Middle cerebellar peduncle
Crus cerebri of
cerebral peduncles
(midbrain)
Thalamus
View (b)
Infundibulum
Superior colliculus
Pituitary gland
Inferior colliculus
Trochlear nerve (IV)
Trigeminal nerve (V)
Superior cerebellar peduncle
Pons
Middle cerebellar peduncle
Facial nerve (VII)
Inferior cerebellar peduncle
Abducens nerve (VI)
Vestibulocochlear nerve (VIII)
Glossopharyngeal nerve (IX)
Olive
Hypoglossal nerve (XII)
Thalamus
Vagus nerve (X)
Diencephalon
Hypothalamus
Accessory nerve (XI)
Midbrain
Pons
Brainstem
Medulla
oblongata
(b) Left lateral view
Figure 12.15b

26. • Superior cerebellar peduncle Pons • Middle cerebellar peduncle
Thalamus
View (c)
Diencephalon
Midbrain
• Superior colliculus
Corpora
quadrigemina
of tectum
• Inferior colliculus
• Trochlear nerve (IV)
Pineal gland
• Superior cerebellar peduncle
Pons
• Middle cerebellar peduncle
Medulla oblongata
Anterior wall of
fourth ventricle
• Inferior cerebellar peduncle
• Facial nerve (VII)
• Vestibulocochlear nerve (VIII)
Choroid plexus
(fourth ventricle)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
Dorsal median sulcus
Thalamus
Dorsal root of
first cervical nerve
Diencephalon
Hypothalamus
Midbrain
Pons
Brainstem
(c) Dorsal view
Medulla
oblongata
Figure 12.15c

27. Midbrain Located between the diencephalon and the pons
Cerebral peduncles
Contain pyramidal motor tracts
Cerebral aqueduct
Channel between third and fourth ventricles

28. Pons Forms part of the anterior wall of the fourth ventricle
Fibers of the pons
Connect higher brain centers and the spinal cord
Relay impulses between the motor cortex and the cerebellum
Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial)
Nuclei that help maintain normal rhythm of breathing

29. Medulla Oblongata Joins spinal cord at foramen magnum
Forms part of the ventral wall of the fourth ventricle
Contains a choroid plexus of the fourth ventricle
Pyramids—two ventral longitudinal ridges formed by pyramidal tracts
Decussation of the pyramids—crossover of the corticospinal tracts

30. Medulla Oblongata
Inferior olivary nuclei—relay sensory information from muscles and joints to cerebellum
Cranial nerves VIII, X, and XII are associated with the medulla
Vestibular nuclear complex—mediates responses that maintain equilibrium
Several nuclei (e.g., nucleus cuneatus and nucleus gracilis) relay sensory information

31. Medulla Oblongata Autonomic reflex centers Cardiovascular center
Cardiac center adjusts force and rate of heart contraction
Vasomotor center adjusts blood vessel diameter for blood pressure regulation

32. Medulla Oblongata Respiratory centers Generate respiratory rhythm
Control rate and depth of breathing, with pontine centers

33. Medulla Oblongata Additional centers regulate Vomiting Hiccuping
Swallowing
Coughing
Sneezing

34. The Cerebellum 11% of brain mass Dorsal to the pons and medulla
Subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction

35. Anatomy of the Cerebellum
Two hemispheres connected by vermis
Each hemisphere has three lobes
Anterior, posterior, and flocculonodular
Folia—transversely oriented gyri
Arbor vitae—distinctive treelike pattern of the cerebellar white matter

36. Anterior lobe Cerebellar cortex Arbor vitae Cerebellar peduncles
Posterior
lobe
• Superior
• Middle
Choroid
plexus of
fourth
ventricle
• Inferior
Medulla
oblongata
Flocculonodular
lobe
(b)
Figure 12.17b

37. Anterior
lobe
Posterior
lobe
(d)
(d)
Vermis
Figure 12.17d

38. Cerebellar Peduncles All fibers in the cerebellum are ipsilateral
Three paired fiber tracts connect the cerebellum to the brain stem
Superior peduncles connect the cerebellum to the midbrain
Middle peduncles connect the pons to the cerebellum
Inferior peduncles connect the medulla to the cerebellum

39. Cerebellar Processing for Motor Activity
Cerebellum receives impulses from the cerebral cortex of the intent to initiate voluntary muscle contraction
Signals from proprioceptors and visual and equilibrium pathways continuously “inform” the cerebellum of the body’s position and momentum
Cerebellar cortex calculates the best way to smoothly coordinate a muscle contraction
A “blueprint” of coordinated movement is sent to the cerebral motor cortex and to brain stem nuclei

40. Cognitive Function of the Cerebellum
Recognizes and predicts sequences of events during complex movements
Plays a role in nonmotor functions such as word association and puzzle solving