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G03: Overview of the CNS/PNS

David A. Morton, Ph.D.

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Neurons -

Functional unit of the nervous system

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CNS

MotorSensory

PNS

(afferent) (efferent)

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CNS – Meninges

• Dura mater

• Arachnoid mater

• Pia mater

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CNS – Meninges

GAFS Fig. 2.59

The Spinal Cord

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CNS – Spinal Cord

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CNS – Spinal Cord

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CNS – Spinal Cord

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CNS – Spinal Cord

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GAFS Fig. 2.80

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CNS – Spinal Cord cont …

GAFS Fig. 2.59

The Spinal Cord

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GAFS Fig. 2.59

The Spinal Cord

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Spinal Nerves

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Spinal Roots and Spinal Nerves

Nerve vs. Neuron

PNS- Spinal Nerves

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Regions of the Spinal Cord and Verterbral Column

Region Number of Spinal Nerves

Number of Vertebrae

Cervical 8 7

Thoracic 12 12

Lumbar 5 5

Sacral 5 5

Coccygeal 1 4

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Rami

At each spinal cord level:

• Roots join to become spinal nerves

• Spinal nerves divide into rami

• Posterior rami – back

• Anterior rami – neck, thorax, abdomen, pelvis,

perineum, limbs

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• Vertebral level

• Spinal cord level

• Spinal nerve level

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PNS – Sensory neurons

Conduct sensory information from the tissues

of the body to the CNS (via dorsal roots)

Pg. 23Dorsal root = Posterior root

PNS – Motor neurons

Conduct motor information from the CNS to

the tissues of the body (via ventral roots)

Ventral root = Anterior rootPg. 23

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PNS – Dermatomes

Spinal nerves are segmentally arranged Pg. 15

Anterior rami

GAFS Fig. 3.32

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Anterior rami

• Cervical plexus

• Brachial plexus

• Thoracic nn.

• Lumbar plexus

• Sacral plexus

NS Overview

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