Lecture Human anatomy and physiology - Chapter 12: The central nervous system (part b)

Chapter 12 - The central nervous system (part b), this chapter includes contents: Lateralization of cortical function, cerebral white matter, basal nuclei (ganglia), functions of basal nuclei, diencephalon, thalamus, thalamic function, hypothalamic function,...

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PowerPoint ® Lecture Slides

prepared by Janice Meeking, Mount Royal College

C H A P T E R 12

The Central Nervous

System:

Part B

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Lateralization of Cortical Function

• Lateralization

• Cerebral dominance

language (left hemisphere in 90% of people)

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Lateralization of Cortical Function

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Cerebral White Matter

• Myelinated fibers and their tracts

• Responsible for communication

gray matter of the two hemispheres

the same hemisphere

hemispheres with lower brain or spinal cord

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Corona radiata

Projection fibers

Longitudinal fissure

Gray matter White matter

Association fibers

Internal capsule

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Basal Nuclei (Ganglia)

• Subcortical nuclei

• Consists of the corpus striatum

• Functionally associated with the subthalamic nuclei (diencephalon) and the substantia nigra (midbrain)

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lentiform nucleus

Caudate

Tail of caudate nucleus

Lentiform nucleus

• Putamen

• Globus pallidus

(deep to putamen)

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Corpus callosum Anterior horn

of lateral ventricle

Caudate nucleus Putamen

Lentiform nucleus

(b)

Globus pallidus

Thalamus Tail of caudate nucleus Third ventricle

Cerebral cortex Cerebral white matter

Anterior

Posterior

Inferior horn

of lateral ventricle

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Functions of Basal Nuclei

• Though somewhat elusive, the following are thought to be functions of basal nuclei

movements

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• Encloses the third ventricle

PLAY Animation: Rotatable brain (sectioned)

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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

Spinal cord

brain

Mid-Fornix

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• 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

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Dorsal nuclei Medial

Ventral lateral

Ventral postero- lateral

Lateral geniculate body

Medial geniculate body

Pulvinar

Lateral dorsal

Lateral posterior

(a) The main thalamic nuclei (The reticular nuclei that “cap” the

thalamus laterally are depicted as curving translucent structures.)

Ventral nuclei

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Thalamic Function

• 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

learning, and memory

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Hypothalamus

• Forms the inferolateral walls of the third ventricle

• Contains many nuclei

• Infundibulum—stalk that connects to the pituitary gland

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nucleus

Supraoptic nucleus Supra- chiasmatic nucleus

Anterior

hypothalamic

nucleus

Dorsomedial nucleus

Paraventricular nucleus

Fornix

Anterior

commissure

Posterior hypothalamic nucleus

Lateral hypothalamic area

Ventromedial nucleus

Mammillary body

(b) The main hypothalamic nuclei.

Arcuate nucleus

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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

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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

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Epithalamus

• Most dorsal portion of the diencephalon;

forms roof of the third ventricle

• Pineal gland—extends from the posterior

border and secretes melatonin

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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

Spinal cord

brain

Mid-Fornix

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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

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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

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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

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View (c)

Diencephalon

Brainstem

Thalamus Hypothalamus Midbrain Pons Medulla oblongata

• Inferior colliculus

• Trochlear nerve (IV)

• Superior cerebellar peduncle

Corpora quadrigemina

of tectum

Medulla oblongata

• Inferior cerebellar peduncle

• Facial nerve (VII)

• Vestibulocochlear nerve (VIII)

• Glossopharyngeal nerve (IX)

• Vagus nerve (X)

• Accessory nerve (XI)

Pons

• Middle cerebellar peduncle

Dorsal median sulcus

Choroid plexus

(fourth ventricle)

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Midbrain Nuclei

IV (trochlear)

• Superior colliculi—visual reflex centers

• Inferior colliculi—auditory relay centers

motor pathways and part of reticular formation

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Dorsal

Cerebral aqueduct

Superior colliculus

Reticular formation

Crus cerebri of cerebral peduncle

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• Connect higher brain centers and the spinal cord

• Relay impulses between the motor cortex and the

cerebellum

and VII (facial)

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Reticular formation

Trigeminal nerve (V)

Pontine nuclei Fibers of pyramidal tract

Middle cerebellar peduncle

Trigeminal main sensory nucleus Trigeminal

motor nucleus

Superior cerebellar peduncle

Medial lemniscus

Fourth ventricle

(b) Pons

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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

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• 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

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diameter for blood pressure regulation

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• Respiratory centers

pontine centers

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Choroid plexus Fourth ventricle

Pyramid Medial lemniscus

Inferior olivary nucleus

Nucleus ambiguus

Inferior cerebellar

Vestibular nuclear complex (VIII)

Solitary nucleus Dorsal motor nucleus

of vagus (X) Hypoglossal nucleus (XII)

(c) Medulla oblongata

Lateral nuclear group Medial nuclear group Raphe nucleus

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The Cerebellum

• 11% of brain mass

• Dorsal to the pons and medulla

• Subconsciously provides precise timing and appropriate patterns of skeletal muscle

contraction

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Anatomy of the Cerebellum

• Two hemispheres connected by vermis

• Each hemisphere has three lobes

• Folia—transversely oriented gyri

• Arbor vitae—distinctive treelike pattern of the cerebellar white matter

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Medulla oblongata Flocculonodular lobe

Choroid plexus of fourth ventricle

Posterior lobe

Arbor vitae

Cerebellar cortex Anterior lobe

Cerebellar peduncles

• Superior

• Middle

• Inferior

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Cerebellar Peduncles

• All fibers in the cerebellum are ipsilateral

• Three paired fiber tracts connect the

cerebellum to the brain stem

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Cerebellar Processing for Motor Activity

cortex of the intent to initiate voluntary muscle

contraction

equilibrium pathways continuously “inform” the

cerebellum of the body’s position and momentum

smoothly coordinate a muscle contraction

cerebral motor cortex and to brain stem nuclei

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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

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