SPPA 2050 Speech Anatomy & Physiology 1 The Central Nervous System

SPPA 2050 Speech Anatomy & Physiology

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The Central Nervous System


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OutlineI. Anatomy of the Nervous System

II. Afferent and Efferent Pathways

III. Centers and Circuits for the Neural Control of Speech


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i. Central Nervous System

ii. Peripheral Nervous System

iii. Nourishment and Protection


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i. Central Nervous System• Basic Organization• Cerebral Hemispheres• Basal Ganglia (Nuclei)• Thalamus & Hypothalamus• Cerebellum• Limbic System• Brainstem• Spinal Cord


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Basic CNS Organization

I. Spinal cord

II. Braina. Hindbrain

Medulla Pons Cerebellum

b. Midbrain

c. Forebrain Thalamus Hypothalamus Basal ganglia Cerebrum


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I. Spinal cord

II. Braina. Hindbrain

Medulla Pons Cerebellum

b. Midbrain

c. Forebrain Thalamus Hypothalamus Basal ganglia Cerebrum

brainstem


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CNS is made up of gray matter and white matter


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White matter

• Contains axons that communicate between CNS structures• Why white?

• Contains myelin (which is fatty) which insulates axons• When you think white matter, think connections between

brain regions.


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Gray matter

• contains cell bodies and synapses that allow communication between neurons.

• Place of integration/modulation of CNS activity.• Nucleus: collection of CNS cell bodies• When you think gray matter, think cell bodies &

synapses between individual neurons.


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White and gray matter

White matter,

Gray matter

Transverse Section of Brain


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White and gray matter

White matter, which stains dark(Weigert stain)

Gray matter, which stains light

Cross-Section of Caudal Brainstem


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Basic CNS Organization• The CNS is generally “symmetric”

Cross-Section of Brainstem (Level 3)

sinistral dextral


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i. Central Nervous System• Basic Organization• Cerebral Hemispheres• Basal Nuclei (Basal Ganglia)• Thalamus & Hypothalamus• Cerebellum• Limbic System• Brainstem• Spinal Cord


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Cerebral Hemispheres


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• Largest part of the brain• wrinkled surface or cortex (bark)

– ↑ ↑ ↑ surface area– Principally gray matter (synapses)– organized in layers


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Cerebral Cortex: Basic Structure


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Cerebral Cortex: Basic Structure

• Gyrus– outfolding of cortex

• Sulcus/fissure– infolding of cortex


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Longitudinal fissure


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Lobes of Cerebral Cortex

Figure 39.12


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Insula: Lobe or region?


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Sulci & Brodmann Areas

Figure 39.11


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Relation between anatomy and function

Kent (1997)


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Communicating between brain structures

• Performed by axonal fibers (i.e. white matter)

• Fasciculi – bundles of axonal fibers


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Communicating between brain structures

Types of fibers• Association fibers

– connect cortical areas in the same hemisphere• short (i.e. gyrus to next gyrus) • long (i.e. connecting lobes)

• Commissural fibers– connect hemispheres

• Projection fibers– Projects to/from the brainstem and spinal cord


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Some fasciculi of the cerebral cortex(long association fibers)

Kent (1997)


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Commissural fibers of the cerebral cortex

• Corpus callosum• Anterior commissure• Middle commissure• Posterior commissure

Figure 39.31


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Corona radiata & internal capsule

Figure 39.8


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i. Central Nervous System• Basic Organization• Cerebral Hemispheres• Basal Ganglia (Nuclei)• Thalamus & Hypothalamus• Cerebellum• Limbic System• Brainstem• Spinal Cord


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Basal ganglia (nuclei)


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A collection of nuclei including• caudate nucleus• putamen • globus pallidus• subthalamic nucleus• substantia nigra

• putamen + globus pallidus = lentiform nucleus• caudate nucleus + putamen = corpus striatum


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Basal ganglia (nuclei)Caudate nucleus

head

body

tail

Lentiform nucleus

Netter


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Figure 39.9 Transverse Figure 39.7 Coronal


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Basal ganglia (nuclei)Function

• involved in movement control

• Does not directly connect to motorneurons

• Helps stabilize the motor system

Diseases

• Parkinson’s Disease

– reduced movement

• Huntington’s Chorea

– uncontrolled “dancing” like movement

• Hemiballismus

– Uncontrolled rapid movements


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Thalamus


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Thalamus

Figure 39.9 Transverse Figure 39.7 Coronal


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Thalamus

Figure 39.16


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Thalamus

Netter


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ThalamusBasic Anatomy• Is a collection of nuclei• All sensory information (exception olfaction) passes through

thalamus en route to cerebral cortex• Information from basal ganglia and cerebellum reaches cortex via

the thalamus• “gateway to the cortex”

Function• integration site for

– Sensory information from different modalities– Complex behavior (language)– Motor processes– Emotional circuits


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Thalamic nuclei• Anterior & mediodorsal nuclei

– Connected to emotional circuits

• Ventral anterior and ventral lateral nuclei– input from basal ganglia and cerebellum

• Ventral posterior lateral (VPL) and medial (VPM)– relays general sensory information from body (VPL) and

head (VPM)

• Medial geniculate body– Relays/processes auditory information

• Lateral geniculate body– Relays/processes visual information


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Hypothalamus

Figure 39.16


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HypothalamusBasic Anatomy• Located inferior to the thalamus (hence “hypo”)

Function• Controls ‘autonomic behavior such as

– release of hormones– control of food and water intake– sexual behavior– sleep cycles– emotional responses

• Indirect role in speech (unless you include flirting)


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Cerebellum

Figure 39.6


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Cerebellum & Brainstem

Figure 39.6


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Cerebellum

• Cerebellum ~ “little brain”• Contains ~ ½ neurons in the entire brain• Attached to dorsal brainstem by peduncles

– Inferior cerebellar peduncle– middle cerebellar peduncle– superior cerebellar peduncle


47Figures 39.16,39.18

Cerebellar peduncles(new slide)


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Cerebellum

• White matter– Fibers going into and out of the cerebellum via peduncles

• Gray matter– Cerebellar cortex– deep cerebellar nuclei


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Cerebellar gray matter(new slide)

From Netter


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CerebellumCerebellar cortex

What is it?– Primary information receiving areaHow is information received? – Inferior and middle cerebellar pedunclesWhere does the information come from? – other motor control centers– vestibular system (balance)– Information about body position via brainstem

and spinal cord


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CerebellumDeep Cerebellar Nuclei

What is it?– Primary information sending areaHow does it send information?– superior cerebellar peduncleWhere does it send information?– brainstem and spinal cord– Cerebral cortex via thalamus


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Function• Coordinates muscles for smooth fluid motion• Monitors “state” of body in space• Monitors/adjusts motor commands Cerebellar Disease/damage• can result in “ataxia”

– Decomposition of movement– Errors in timing and scaling of movement– Tremor during movement activities

Cerebellum


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Limbic System


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Limbic System

Figure 39.13

HippocampusFornixMammillary bodyAmygdala


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Limbic SystemFunction

• Important in regulating emotional and visceral responses

• role in speech/language unclear– damage in the area can cause mutism

(lack of any speech)


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Midbrain

Pons

Medulla

Brainstem: ventral

Figure 39.19


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Midbrain

Pons

Medulla

Brainstem: Dorsal Lateral

Figure 39.19


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Midbrain

Pons

Medulla

Brainstem: dorsal

Figure 39.19


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BrainstemBasic Anatomy• Contains• Projection fibers (called tracts)

– To higher CNS structures from SC/BS– To SC/BS from higher CNS structures

• Nuclei– Associated with cranial nerves– Associated with basic bodily function


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BrainstemFunction• Cranial nerve nuclei

– Motor supply to muscles of speech– Sensory supply to head and neck

• Regulates some essential life functions– Body temperature– Respiration– Swallowing– Digestion


63Figure 39.19


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Superior orbital fissure (CN V: ‘V1’)

Foramen rotundum (CN V: ‘V2’)Foramen ovale (CN V: ‘V3’)

Internal auditory meatus (CN VII & VIII)

Jugular foramen (CN IX, X, XI)

Hypoglossal canal (CN XII)


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Cranial Nerve Nuclei

Figure 31.2


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Where do cranial nerves arise?

Pons• CN V – sourced to a number of BS nuclei• CN VII –motor portion from Facial nucleus

Medulla• CN IX, X, XI – originate largely in nucleus ambiguus• CN XII – originates in Hypoglossal nucleus

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SPPA 2050 Speech Anatomy & Physiology 1 The Central Nervous System