ch-1 introduction to nervous system

8/8/2019 Ch-1 Introduction to Nervous System

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Introduction to Nervous system


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Organization of the Nervous System

Central Nervous System (CNS)Protected by:

Brain Meninges

Spinal Cord CSF

Bones (skull and vertebral column)

Peripheral Nervous System (PNS)Not protected by bone. More vulnerable to injury (crushing/cutting).

Cranial Nerves

Spinal Nerves

Associated Ganglia


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Peripheral Nervous System

1. Spinal nerves: 31 pairs

2. Cranial nerves: 12 pairs

3. Autonomic nerves

Sympathetic

Parasympathetic


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Central Nervous System

The entire CNS is surrounded by Meninges

and suspended in the Cerebrospinal fluid.

Dura mater the outermost and thickest layer

Arachnoid mater the middle layer

Pia mater only a few cells thick this

conforms to the contours of the surface of the

brain and spinal cord


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Associated Spaces of CNS

Epidural

Between the dura mater and the skull/vertebrae

Subdural

Between the dura and arachnoid

Subarachnoid

Between the arachnoid and pia. This is wherethe CSF flows.


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Basic Structures of CNS

Gray matterIs composed ofneuronal cell bodies (nerve cells) embeddedin neuroglia in the cortex of the brain.

White matterIs composed ofglial cells and neuronal axons (nerve fibers)

embedded in neuroglia in the central area of the brain.

NeuronIs composed of a large numbers ofexcitable nerve cells

and their processes.


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Basic Structures of CNS

Glial cells or Neuroglia

Specialized tissues for supporting the Neurons and other

specific functions.

NeuralPertaining to the nervous system and includes neurons and

glia

Neuronal

Only pertaining to neurons.

Nucleus

A group of neurons in the CNS.


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Cells of the Nervous System

Glial cells Neurons

1. Astrocytes

2. Oligodendrocytes

3. Microglia

4. Ependymal cells

5.Shcwann cells


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CNS Ventricles

It is filled w/ CSF produced by choroid plexus.

It includesLateral Ventricles

Third Ventricle

Fourth Ventricle


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CNS Ventricles

Interventricular Foramina

connects the Lateral and Third Ventricles

at the level ofDiencephalon.

Cerebral Aqueduct

Connects Third and Fourth Ventricles atthe level ofMidbrain. It is a narrow cavity.


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Ventricular System

L V L V

3rd

Lateral Ventricles

Third Ventricle

Fourth Ventricle

Cerebral Aqueduct

Central Canal

4th


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Primary Division of CNS

Forebrain

Cerebrum: telencephalon

DiencephalonMidbrain:mesencephalon

Hindbrain: rhombencephalon

Pons and Cerebellum: metenecephalonMedulla oblongata: myelencephalon


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Development of the Brain


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Brain vesicles and their adult derivativesPrimary vesicle Secondary vesicle Adult derivatives

Prosencephalon

(forebrain)

Telencephalon Cerebral hemispheres,Basal ganglia(except

Globus pallidus)

Diencephalon Epithalamus, subthalamus, thalamus,

hypothalamus, penial gland, globus pallidus

Mesencephalon

(midbrain)

Mesencehalon Midbrain

Rhombencephalon

(hindbrain)

Metencephalon Pons & Cerebellum

Mylencephalon Medulla oblangata


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Central Nervous System

BrainBrainstem

Cerebrum Midbrain

Diencephalon Pons

Cerebellum Medulla

Spinal cord segmentsCervical Sacral

Thoracic CoccygealLumbar


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Anatomical Classification of Nervous System


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Spinal Cord

Runs from the medulla

oblongata to L1/L2 in

the adult.

Conus Medullaris

the conical end of the

spinal cord at L1/L2.


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Spinal Cord

Filum Terminalethe extension of the piamater than runs from

the conus medullaris tothe coccyx

Cauda equinaconsists of roots belowthe level of the conusmedullaris


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Spinal Roots

Motor or sensory

These are part of the

CNS

They attach to the

spinal cord by rootlets

at one end and join to

form the spinal nerves

(part of the PNS) at the

other end


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Motor and Sensory Roots

Motor Roots

The cell bodies are inthe anterior horns of

the spinal cord

They always enter

the anterior of thespinal cord

Sensory Roots

The cell bodies are inthe posterior root

ganglion (PRG) inthe PNS

They always enterthe posterior of thespinal cord


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Spinal Nerves

The joining of the motor and sensory roots

forms the spinal nerve.

This immediately splits into posterior andanterior rami.

The roots are in the CNS, the nerves are in the

PNS.

They exit the vertebral column through the

intervertebral foramina.


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Spinal Nerves

31 pairs

Cervical -8

Thoracic -12

Lumbar -5

Sacral -5

Coccygeal-1


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Ganglia

Bundles ofneuronal cells bodies in the

peripheral nervous system

Found in the autonomic nervous system, at

the posterior of the spinal cord and in some

cranial nerves (V, VII, VIII, IXand X).

5, 7, 8, 9, 10


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Spinal Cord Cross Section

Contains the peripherally located anterior,

posterior and lateral white columns

Anterior and posterior horns bilaterally

Gray commissures that connect the horns,and a central canal containing CSF


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Anatomy of the Spinal Cord


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Medulla Oblongata

A part of theHindbrain andBrainstem

conduit forascending and

descending nervefibers; containsmany nuclei .


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Pons

A part of the Hindbrainand Brainstem.

Connects the twocerebellar hemispheres.

Contains many nuclei,

ascending anddescending nerve fibers.


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Cerebellum

Two hemispheres connected byvermis. A part ofHindBrain.

Superior cerebellar peduncleconnects cerebellum to themidbrain.

middle cerebellar peduncleconnects cerebellum to pons.

inferior cerebellar peduncleconnects cerebellum to themedulla.

Cortex of cerebellum consists of

gray matter. Gray matter masses found

inside cerebellar white matterare called nucleidentate isthe largest.


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Midbrain

A part of the

Brainstem

Connects forebrain

to hindbrain

Contains cerebral

aqueduct


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Diencephalon

A part of Forebrain

Thalamusdorsal

Hypothalamusventral


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Cerebrum

A part ofForebrain

Corpus Callosum

connects the two

cerebral hemispheres

Falx cerebri

separates the two

cerebral hemispheres

Cortexcomposed of gray

matter


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Cerebrum

Longitudinal Fissure:separates the twohemispheres

Gyri: folds

Sulci: fissures

Basal nuclei

gray matter in the central coreof white matter

Gray matter

on the outside of the Internal

Capsule White mater

on the inside of the InternalCapsule

Corona radiata

White fibers that pass thefibers from the cerebral cortexto the brainstem

Internal capsule

Corona radiata that passesbetween the basal nuclei

Caudate nucleus

on the medial side the InternalCapsule

Lentiform nucleuson the lateral side of theInternal Capsule


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Cerebrum


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Cerebrum


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ch-1 introduction to nervous system

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