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Chapter 2c CNS Gross Anatomy
Chris RordenUniversity of South CarolinaNorman J. Arnold School of Public HealthDepartment of Communication Sciences and DisordersUniversity of South Carolina
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What is a Fasciculi
In anatomy, a Fasciculi refers to aA. Volume of Cerebral Spinal Fluid
B. White matter fiber tract
C. Gray matter nuclei
D. Set of cells that support neurons
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What is a Fasciculi
What is a fascio?A. A Flag
B. Bundle of rods, sometimes with an axe
C. A spoon
D. A shaft of wheat, used as an ancient straw
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Spinal Cord
Same Meningeal Layers as the BrainAbout 45cm longDiameter of 1 cm.
Root filamentsDorsalVentral
Mixed spinal nerve
Dura mater
Arachnoid mater
Pia mater
Spinal Nerve Components
Dorsal Division: sensory part of nerve, sensory information enters spinal cord through dorsal root fibers
Ganglion: cell bodies of these nerves come together to create the dorsal root ganglion
Dorsal Horn or Column: information enters the spinal column at the dorsal horn
Spinal Nerve Components
Ventral Division: motor commands, leave the ventral root and go to muscles
Ventral Horn or Column: information passed from brain to spinal cord then from the ventral root to the extremities
Transverse view of spinal cord
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Segmental Spinal Reflex Arc
A stimulus/response system that maintains a constant state of muscular tone
Works by:– muscles spindles sense stretching and send information through
gamma nerves to dorsal root of spinal cord– a signal is sent back from the ventral root for the muscle to contract
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Spinal Cord
Dorsal root fibers form ganglionConnect to ventral fibers to form peripheral
spinal nerves.Attached by Filum Terminale
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Internal Spinal Cord
Gray MatterTwo Dorsal Horns (Sensory Info)Two Ventral Horns (Motor Info)White MatterThree Myelinated Fasciculi Dorsal, Lateral and Ventral
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Spinal Cord Segments & Nerves
Lumbar5
Coccygeal1
31 Spinal Segments and Nerves
Cervical8
Thoracic12
Sacral5
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Ventricles
Lateral Ventricles Connected by
interventricular foramen Collateral trigone area Posterior and inferior horns Connects to Third Ventricle
through Monro’s foramen
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Other ventricles…
Third Ventricle Ventral to the corpora
quadrigemina Surrounded by central gray
area Connects to fourth ventricle
through Cerebral Aqueduct Fourth ventricle
– Near Pons / Medulla
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Multiple choice
You are in bed and hear a loud crash – your heart pounds. What part of your CNS is dominant?
A. Parasagittal
B. Sympathetic
C. Parasympathetic
D. Local
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Medullary Centers
Interhemispheric (between) Connections Intrahemispheric (within) ConnectionsThree types of fibers
– Projection: Project through internal capsule– Association: Within a hemisphere
i.e. Arcuate fasciculus– Commissural: Between hemispheres i.e. Corpus
callosum
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Meninges
Three Basic LevelsExtensions of Dura materFalx Cerebri: Vertical partition dipping into
cranial space (Refection)Tentorium Cerebri: Houses the cerebellumFalx Cerebelli: Separates two cerebellar
hemispheres
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Meninges
Arachnoid Trabeculae– Connects Pia and Arachnoid– Inside subarachnoid space
Arachnoid Villi– Specialized protrusions through
which Cerebrospinal Fluid (CSF) leaves the brain
Peripheral Nervous System (PNS)
12 pairs of cranial nerves-– Sensory, motor, or mixed
“On Old Olympus Towering Top A Famous Vocal German Viewed Some Hops.”
31 pairs of spinal nerves
Cranial Nerves (12 pair)
I. Olfactory: sensory for smell
II. Optic: sensory for vision
III. Oculomotor: motor for vision
IV. Trochlear: motor for vision
V. Trigeminal: sensory to eyes, nose, face and meningies; motor to muscles of mastication and tongue
Cranial Nerves
I. Abducen: motor to lateral eye musclesII. Facial: sensory to tongue and soft palate,
motor to muscles of the face and stapesIII. Vestibulocochlear: sensory for hearing and
balance (aka Acoustic)IV. Glossopharyngeal: sensory to tongue,
pharynx, and soft palate; motor to muscles of the the pharynx and stylopharyngeus
Cranial Nerves
I. Vagus Nerve: sensory to ear, pharynx, larynx, and viscera; motor to pharynx, larynx, tongue, and smooth muscles of the viscera, 2 parts: superior laryngeal branch and recurrent laryngeal branch
II. Spinal Accessory Nerve: motor to pharynx, larynx, soft palate and neck
III. Hypoglossal Nerve: motor to strap muscles of the neck, intrinsic and extrinsic muscles of the tongue