Download Chapter 13b - Dr. Jerry Cronin

The Cerebellum
Figure 13–7b The Cerebellum.
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The Cerebellum
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The Mesencephalon
• Structures of the Mesencephalon
• Tectum
• Two pairs of sensory nuclei (corpora quadrigemina):
• superior colliculus (visual)
• inferior colliculus (auditory)
• Tegmentum
• Red nucleus (many blood vessels)
• Substantia nigra (pigmented gray matter)
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The Mesencephalon
• Structures of the Mesencephalon
• Cerebral peduncles
• Nerve fiber bundles on ventrolateral surfaces
• Contain:
• descending fibers to cerebellum
• motor command fibers
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The Mesencephalon
Figure 13–8a The Mesencephalon.
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The Mesencephalon
Figure 13–8b The Mesencephalon.
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The Mesencephalon
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The Diencephalon
• Integrates sensory information and motor commands
• Thalamus, epithalamus, and hypothalamus
• The pineal gland
• Found in posterior epithalamus
• Secretes hormone melatonin
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The Diencephalon
• The Thalamus
• Filters ascending sensory information for primary sensory
cortex
• Relays information between basal nuclei and cerebral
cortex
• The third ventricle
• Separates left thalamus and right thalamus
• Interthalamic adhesion (or intermediate mass):
• projection of gray matter
• extends into ventricle from each side
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The Diencephalon
• The Thalamus
• Thalamic nuclei
• Are rounded masses that form thalamus
• Relay sensory information to basal nuclei and cerebral cortex
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The Diencephalon
• Five Groups of Thalamic Nuclei
• Anterior group
• Anterior nuclei
• Part of limbic system (emotions)
• Medial group
• Provides awareness of emotional states
• Ventral group
• Relays sensory information
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The Diencephalon
• Five Groups of Thalamic Nuclei
• Posterior group
• Pulvinar nucleus (sensory)
• Lateral geniculate nucleus (visual)
• Medial geniculate nucleus (auditory)
• Lateral group
• Affects emotional states
• Integrates sensory information
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The Diencephalon
Figure 13–9 The Thalamus.
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The Diencephalon
Figure 13–9a The Thalamus.
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The Diencephalon
Figure 13–9b The Thalamus.
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The Diencephalon
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The Diencephalon
• The Hypothalamus
• Mamillary bodies
• Process olfactory and other sensory information
• Control reflex eating movements
• Infundibulum
• A narrow stalk
• Connects hypothalamus to pituitary gland
• Tuberal area
• Located between the infundibulum and mamillary bodies
• Helps control pituitary gland function
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The Diencephalon
Figure 13–10a The Hypothalamus in Sagittal Section.
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The Diencephalon
Figure 13–10b The Hypothalamus in Sagittal Section.
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The Diencephalon
• Eight Functions of the Hypothalamus
• Provides subconscious control of skeletal muscle
• Controls autonomic function
• Coordinates activities of nervous and endocrine systems
• Secretes hormones
• Antidiuretic hormone (ADH) by supraoptic nucleus
• Oxytocin (OT; OXT) by paraventricular nucleus
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The Diencephalon
• Eight Functions of the Hypothalamus
• Produces emotions and behavioral drives
• The feeding center (hunger)
• The thirst center (thirst)
• Coordinates voluntary and autonomic functions
• Regulates body temperature
• Preoptic area of hypothalamus
• Controls circadian rhythms (day–night cycles)
• Suprachiasmatic nucleus
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The Diencephalon
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The Limbic System
• The Limbic System
• Is a functional grouping that
• Establishes emotional states
• Links conscious functions of cerebral cortex with autonomic
functions of brain stem
• Facilitates memory storage and retrieval
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The Limbic System
• Components of the Limbic System
• Amygdaloid body
• Acts as interface between the limbic system, the cerebrum, and
various sensory systems
• Limbic lobe of cerebral hemisphere
• Cingulate gyrus
• Dentate gyrus
• Parahippocampal gyrus
• Hippocampus
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The Limbic System
• Components of the Limbic System
• Fornix
• Tract of white matter
• Connects hippocampus with hypothalamus
• Anterior nucleus of the thalamus
• Relays information from mamillary body to cingulate gyrus
• Reticular formation
• Stimulation or inhibition affects emotions (rage, fear, pain, sexual
arousal, pleasure)
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The Limbic System
Figure 13–11a The Limbic System.
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The Limbic System
Figure 13–11b The Limbic System.
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The Limbic System
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The Cerebrum
• The Cerebrum
• Is the largest part of the brain
• Controls all conscious thoughts and intellectual functions
• Processes somatic sensory and motor information
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The Cerebrum
• Gray matter
• In cerebral cortex and basal nuclei
• White matter
• Deep to basal cortex
• Around basal nuclei
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The Cerebrum
• Structures of the Cerebrum
• Gyri of neural cortex
• Increase surface area (number of cortical neurons)
• Insula (island) of cortex
• Lies medial to lateral sulcus
• Longitudinal fissure
• Separates cerebral hemispheres
• Lobes
• Divisions of hemispheres
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The Cerebrum
• Structures of the Cerebrum
• Central sulcus divides
• Anterior frontal lobe from posterior parietal lobe
• Lateral sulcus divides
• Frontal lobe from temporal lobe
• Parieto-occipital sulcus divides
• Parietal lobe from occipital lobe
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The Cerebrum
Figure 13–12a The Brain in Lateral View.
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The Cerebrum
Figure 13–12b The Brain in Lateral View.
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The Cerebrum
Figure 13–12c The Brain in Lateral View.
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The Cerebrum
• Three Functional Principles of the Cerebrum
• Each cerebral hemisphere receives sensory information
from, and sends motor commands to, the opposite side of
the body
• The two hemispheres have different functions, although
their structures are alike
• Correspondence between a specific function and a specific
region of cerebral cortex is not precise
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The Cerebrum
• White Matter of the Cerebrum
• Association fibers
• Commissural fibers
• Projection fibers
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The Cerebrum
• White Matter of the Cerebrum
• Association fibers
• Connections within one hemisphere:
• arcuate fibers:
• are short fibers
• connect one gyrus to another
• longitudinal fasciculi:
• are longer bundles
• connect frontal lobe to other lobes in same hemisphere
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The Cerebrum
• White Matter of the Cerebrum
• Commissural fibers
• Bands of fibers connecting two hemispheres:
• corpus callosum
• anterior commissure
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The Cerebrum
• White Matter of the Cerebrum
• Projection fibers
• Pass through diencephalon
• Link cerebral cortex with:
• diencephalon, brain stem, cerebellum, and spinal cord
• Internal capsule:
• all ascending and descending projection fibers
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The Cerebrum
Figure 13–13a Fibers of the White Matter of the Cerebrum.
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The Cerebrum
Figure 13–13b Fibers of the White Matter of the Cerebrum.
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The Cerebrum
• The Basal Nuclei
• Also called cerebral nuclei
• Are masses of gray matter
• Are embedded in white matter of cerebrum
• Direct subconscious activities
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The Cerebrum
• Structures of Basal Nuclei
• Caudate nucleus
• Curving, slender tail
• Lentiform nucleus
• Globus pallidus
• Putamen
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The Cerebrum
Figure 13–14a The Basal Nuclei.
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The Cerebrum
Figure 13–14b The Basal Nuclei.
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The Cerebrum
Figure 13–14c The Basal Nuclei.
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The Cerebrum
• Functions of Basal Nuclei
• Involved with
• The subconscious control of skeletal muscle tone
• The coordination of learned movement patterns (walking, lifting)
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The Cerebrum
• Motor and Sensory Areas of the Cortex
• Central sulcus separates motor and sensory areas
• Motor areas
• Precentral gyrus of frontal lobe:
• directs voluntary movements
• Primary motor cortex:
• is the surface of precentral gyrus
• Pyramidal cells:
• are neurons of primary motor cortex
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The Cerebrum
• Motor and Sensory Areas of the Cortex
• Sensory areas
• Postcentral gyrus of parietal lobe:
• receives somatic sensory information (touch, pressure, pain,
vibration, taste, and temperature)
• Primary sensory cortex:
• surface of postcentral gyrus
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The Cerebrum
• Special Sensory Cortexes
• Visual cortex
• Information from sight receptors
• Auditory cortex
• Information from sound receptors
• Olfactory cortex
• Information from odor receptors
• Gustatory cortex
• Information from taste receptors
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The Cerebrum
Figure 13–15a Motor and Sensory Regions of the Cerebral Cortex.
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The Cerebrum
• Association Areas
• Sensory association areas
• Monitor and interpret arriving information at sensory areas of
cortex
• Somatic motor association area (premotor cortex)
• Coordinates motor responses (learned movements)
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The Cerebrum
• Sensory Association Areas
• Somatic sensory association area
• Interprets input to primary sensory cortex (e.g., recognizes and
responds to touch)
• Visual association area
• Interprets activity in visual cortex
• Auditory association area
• Monitors auditory cortex
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The Cerebrum
• Integrative Centers
• Are located in lobes and cortical areas of both cerebral
hemispheres
• Receive information from association areas
• Direct complex motor or analytical activities
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The Cerebrum
• General Interpretive Area
• Also called Wernicke area
• Present in only one hemisphere
• Receives information from all sensory association areas
• Coordinates access to complex visual and auditory
memories
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The Cerebrum
• Other Integrative Areas
• Speech center
• Is associated with general interpretive area
• Coordinates all vocalization functions
• Prefrontal cortex of frontal lobe
• Integrates information from sensory association areas
• Performs abstract intellectual activities (e.g., predicting
consequences of actions)
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The Cerebrum
Figure 13–15b Motor and Sensory Regions of the Cerebral Cortex.
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The Cerebrum
• Interpretive Areas of Cortex
• Brodmann areas
• Patterns of cellular organization in cerebral cortex
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The Cerebrum
Figure 13–15c Motor and Sensory Regions of the Cerebral Cortex.
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The Cerebrum
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The Cerebrum
• Hemispheric Lateralization
• Functional differences between left and right hemispheres
• Each cerebral hemisphere performs certain functions that
are not ordinarily performed by the opposite hemisphere
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The Cerebrum
• The Left Hemisphere
• In most people, left brain (dominant hemisphere) controls
• Reading, writing, and math
• Decision making
• Speech and language
• The Right Hemisphere
• Right cerebral hemisphere relates to
• Senses (touch, smell, sight, taste, feel)
• Recognition (faces, voice inflections)
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The Cerebrum
Figure 13–16 Hemispheric Lateralization.
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The Cerebrum
• Monitoring Brain Activity
• Brain activity is assessed by an electroencephalogram
(EEG)
• Electrodes are placed on the skull
• Patterns of electrical activity (brain waves) are printed out
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The Cerebrum
• Four Categories of Brain Waves
• Alpha waves
• Found in healthy, awake adults at rest with eyes closed
• Beta waves
• Higher frequency
• Found in adults concentrating or mentally stressed
• Theta waves
• Found in children
• Found in intensely frustrated adults
• May indicate brain disorder in adults
• Delta waves
• During sleep
• Found in awake adults with brain damage
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The Cerebrum
Figure 13–17a-d Brain Waves.
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The Cerebrum
• Synchronization
• A pacemaker mechanism
• Synchronizes electrical activity between hemispheres
• Brain damage can cause desynchronization
• Seizure
• Is a temporary cerebral disorder
• Changes the electroencephalogram
• Symptoms depend on regions affected
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Cranial Nerves
• 12 pairs connected to brain
• Four Classifications of Cranial Nerves
• Sensory nerves: carry somatic sensory information,
including touch, pressure, vibration, temperature, and pain
• Special sensory nerves: carry sensations such as smell,
sight, hearing, balance
• Motor nerves: axons of somatic motor neurons
• Mixed nerves: mixture of motor and sensory fibers
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Cranial Nerves
• Cranial nerves are classified by primary functions
• May also have important secondary functions
• Distributing autonomic fibers to peripheral ganglia
• The 12 cranial nerve groups are identified by
• Primary function
• Origin
• Pathway
• Destination
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Cranial Nerves
Figure 13–18 Origins of the Cranial Nerves.
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Cranial Nerves
• Olfactory Nerves (I)
• Primary function
• Special sensory (smell)
• Origin
• Receptors of olfactory epithelium
• Pathway
• Olfactory foramina in cribriform plate of ethmoid
• Destination
• Olfactory bulbs
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Cranial Nerves
• Olfactory Nerve Structures
• Olfactory bulbs
• Located on either side of crista galli
• Olfactory tracts
• Axons of postsynaptic neurons
• Leading to cerebrum
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Cranial Nerves
Figure 13–19 The Olfactory Nerve.
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Cranial Nerves
• Optic Nerves (II)
• Primary function
• Special sensory (vision)
• Origin
• Retina of eye
• Pathway
• Optic canals of sphenoid
• Destination
• Diencephalon via optic chiasm
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Cranial Nerves
• Optic Nerve Structures
• Optic chiasm
• Where sensory fibers converge
• And cross to opposite side of brain
• Optic tracts
• Reorganized axons
• Leading to lateral geniculate nuclei
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Cranial Nerves
Figure 13–20 The Optic Nerve.
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Cranial Nerves
• Oculomotor Nerves (III)
• Primary function
• Motor (eye movements)
• Origin
• Mesencephalon
• Pathway
• Superior orbital fissures of sphenoid
• Destination
• Somatic motor:
• superior, inferior, and medial rectus muscles
• inferior oblique muscle
• levator palpebrae superioris muscle
• Visceral motor:
• intrinsic eye muscles
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Cranial Nerves
• Oculomotor Nerve Structures
• Oculomotor nerve
• Controls four of six eye-movement muscles
• Delivers autonomic fibers to ciliary ganglion:
• ciliary ganglion: controls intrinsic muscles of iris and lens
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Cranial Nerves
• The Trochlear Nerves (IV)
• Primary function
• Motor (eye movements)
• Origin
• Mesencephalon
• Pathway
• Superior orbital fissure of sphenoid
• Destination
• Superior oblique muscle
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Cranial Nerves
• The Abducens Nerves (VI)
• Primary function
• Motor (eye movements)
• Origin
• Pons
• Pathway
• Superior orbital fissures of sphenoid
• Destination
• Lateral rectus muscle
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Cranial Nerves
Figure 13–21 Cranial Nerves Controlling the Extra-Ocular Muscles.
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Cranial Nerves
• The Trigeminal Nerves (V)
• Primary function
• Mixed (sensory and motor) to face
• Origin
• Ophthalmic branch (sensory):
• orbital structures
• nasal cavity
• skin of forehead, upper eyelid, and eyebrow
• part of nose
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Cranial Nerves
• The Trigeminal Nerves (V)
• Origin
• Maxillary branch (sensory):
•
•
•
•
lower eyelid
upper lip, gums, and teeth
cheek and nose
palate and part of pharynx
• Mandibular branch (sensory):
• lower gums, teeth, and lips
• palate and part of tongue
• Mandibular branch (motor):
• motor nuclei of pons
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Cranial Nerves
• The Trigeminal Nerves (V)
• Pathway
• Ophthalmic branch:
• superior orbital fissure
• Maxillary branch:
• foramen rotundum
• Mandibular branch:
• foramen ovale
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Cranial Nerves
• The Trigeminal Nerves (V)
• Destination
• Sensory nerves:
• sensory nuclei in pons
• Motor nerves of mandibular branch:
• muscles of mastication
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Cranial Nerves
• Trigeminal Nerve Structures
• Trigeminal nerves
• Largest cranial nerves
• With three major branches
• Semilunar ganglion
• Contains cell bodies of sensory neurons
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Cranial Nerves
Figure 13–22 The Trigeminal Nerve.
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Cranial Nerves
• The Facial Nerves (VII)
• Primary function
• Mixed (sensory and motor) to face
• Origin
• Sensory:
• taste receptors on anterior 2/3 of tongue
• Motor:
• motor nuclei of pons
• Pathway
• Internal acoustic meatus to facial canals (stylomastoid foramina)
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Cranial Nerves
• The Facial Nerves (VII)
• Destination
• Sensory:
• sensory nuclei of pons
• Somatic motor:
• muscles of facial expression
• Visceral motor:
• tear and nasal mucous glands
• submandibular and sublingual salivary glands
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Cranial Nerves
• Facial Nerve Structures
• Facial nerve branches
• Temporal
• Zygomatic
• Buccal
• Mandibular
• Cervical branches
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Cranial Nerves
• Facial Nerve Structures
• Geniculate ganglia
• Hold cell bodies of sensory neurons
• Pterygopalatine ganglia
• Postganglionic fibers innervate glands (lacrimal, nasal cavity, and
pharynx)
• Submandibular ganglia
• Innervate salivary glands
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Cranial Nerves
Figure 13–23a The Facial Nerve.
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Cranial Nerves
Figure 13–23b The Facial Nerve.
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Cranial Nerves
• The Vestibulocochlear Nerves (VIII)
• Primary function: special sensory
• Vestibular branch:
• balance and equilibrium
• Cochlear branch:
• hearing
• Origin
• Receptors of inner ear
• Pathway
• Internal acoustic meatus of temporal bones
• Destination
• Vestibular and cochlear nuclei of pons and medulla oblongata
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Cranial Nerves
• Vestibulocochlear Nerve Structures
• Vestibular branch
• Originates at receptors of vestibule (balance)
• Connects to vestibular nuclei of pons and medulla oblongata
• Cochlear branch
• Originates at sensors of cochlea (hearing)
• Connects with cochlear nuclei of pons and medulla oblongata
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Cranial Nerves
Figure 13–24 The Vestibulocochlear Nerve.
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Cranial Nerves
• The Glossopharyngeal Nerves (IX)
• Primary function
• Mixed (sensory and motor) to head and neck
• Origins
• Sensory:
• posterior 1/3 of tongue
• part of pharynx and palate
• carotid arteries
• Motor:
• motor nuclei of medulla oblongata
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Cranial Nerves
• The Glossopharyngeal Nerves (IX)
• Pathway
• Jugular foramina between occipital and temporal bones
• Destination
• Sensory:
• sensory nuclei of medulla oblongata
• Somatic motor:
• nerves involved in swallowing
• Visceral motor:
• parotid salivary gland
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Cranial Nerves
• Glossopharyngeal Nerve Structures
• Superior and inferior ganglion
• Sensory neurons of tongue and pharynx
• Otic ganglion
• Synapse visceral motor fibers
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Cranial Nerves
Figure 13–25 The Glossopharyngeal Nerve.
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Cranial Nerves
• The Vagus Nerves (X)
• Primary function
• Mixed (sensory and motor)
• Widely distributed in thorax and abdomen
• Origins
• Sensory:
•
•
•
•
part of pharynx
auricle and external acoustic meatus
diaphragm
visceral organs of thoracic and abdominopelvic cavities
• Motor:
• motor nuclei in medulla oblongata
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Cranial Nerves
• The Vagus Nerves (X)
• Pathway
• Jugular foramina
• Between occipital and temporal bones
• Destination
• Sensory:
• sensory nuclei and autonomic centers of medulla oblongata
• Visceral motor:
• muscles of the palate and pharynx
• muscles of the digestive, respiratory, and cardiovascular systems in
thoracic and abdominal cavities
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Cranial Nerves
• Vagus Nerve Structures
• Vagus nerves
• Branch and radiate extensively
• Superior (jugular) ganglion and inferior (nodose) ganglion
• Hold sensory neurons
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Cranial Nerves
Figure 13–26 The Vagus Nerve.
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Cranial Nerves
Figure 13–26 The Vagus Nerve.
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Cranial Nerves
• The Accessory Nerves (XI)
• Primary function
• Motor to muscles of neck and upper back
• Origin
• Motor nuclei of spinal cord and medulla oblongata
• Pathway
• Jugular foramina between occipital and temporal bones
• Destination
• Internal branch:
• voluntary muscles of palate, pharynx, and larynx
• External branch:
• sternocleidomastoid and trapezius muscles
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Cranial Nerves
• Accessory Nerve Structures
• Spinal root
• Motor fibers that originate in anterior gray horns of first five
cervical segments of spinal cord
• Cranial root
• Motor fibers that originate in medulla oblongata
• Internal branch
• Joins the vagus nerve
• External branch
• Controls muscles of neck and back
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Cranial Nerves
• The Hypoglossal Nerves (XII)
• Primary function
• Motor (tongue movements)
• Origin
• Motor nuclei of medulla oblongata
• Pathway
• Hypoglossal canals of occipital bone
• Destination
• Muscles of tongue
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Cranial Nerves
Figure 13–27 The Accessory and Hypoglossal Nerves.
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Cranial Nerves
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Cranial Nerves
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Cranial Reflexes
• Cranial Reflexes
• Monosynaptic and polysynaptic reflex arcs
• Involve sensory and motor fibers of cranial nerves
• Clinically useful to check cranial nerve or brain damage
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Cranial Reflexes
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