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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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Ventricles

Birds Eye View– Usually symmetrical in healthy people

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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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Ventricles

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Ventricles in clinical setting

Hydrocephalus– E.G. cyst

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White matter fibers from the cortex

Brain stem connects to cortex

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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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Multiple choice

What view of the brain is this?A. Sagittal

B. Axial

C. Coronal

D. Sympathetic

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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