CHAPTER 17The Spinal Cord and the Spinal Nerves

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

Connective tissue coveringsConnective tissue coverings

Bony VertebraeBony VertebraeMeningesMeningesDura MaterDura MaterSubdural space Subdural space –– interstitial fluidinterstitial fluid

ArachnoidArachnoid MaterMaterSubarachnoid space Subarachnoid space -- CSFCSF

PiaPia MaterMater

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Cross section of spinal cordCross section of spinal cord

Sensory & Motor TractsSensory & Motor Tracts 18_04a18_04a

ReflexesReflexes Spinal ReflexesSpinal Reflexes

Cranial ReflexesCranial Reflexes

Somatic reflexesSomatic reflexes

Autonomic reflexesAutonomic reflexes

Spinal reflex componentsSpinal reflex components ReceptorReceptor

Sensory neuronSensory neuron

Integrating centerIntegrating center

Motor neuronMotor neuron

EffectorEffector

18_1218_12 Anatomy of a NerveAnatomy of a Nerve

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Cervical PlexusCervical Plexus

PhrenicPhrenic nervenerveSupplies the Supplies the diaphramdiaphram

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18_06b18_06b Brachial PlexusBrachial Plexus MusculocutaneousMusculocutaneous n. n.

Flexors of the forearmFlexors of the forearm Radial n.Radial n.

Muscles of the back of the arm and forearmMuscles of the back of the arm and forearm Median n.Median n.

Flexors of forearm & muscles of lateral palm; skin of Flexors of forearm & muscles of lateral palm; skin of lateral 2/3 of palm & fingerslateral 2/3 of palm & fingers

UlnarUlnar n.n. Flexor Flexor carpicarpi unlnarusunlnarus & flexor dig. & flexor dig. profundusprofundus,; most ,; most

muscles of hand; skin on medial hand; little finger & muscles of hand; skin on medial hand; little finger & medial medial ½½ of ring fingerof ring finger

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Lumbar plexusLumbar plexus

Femoral n.Femoral n. Thigh flexors & extensors; skin over Thigh flexors & extensors; skin over

anterior & medial thigh , medial leg & footanterior & medial thigh , medial leg & foot

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Sacral plexusSacral plexus

Sciatic n.Sciatic n. 2 nerves 2 nerves –– tibialtibial & common & common peronealperoneal in in

one sheathone sheath Largest nerve in the bodyLargest nerve in the body

PudendalPudendal n.n.Muscles of perineumMuscles of perineum Skin of penis and Skin of penis and scotumscotumClitoris, labia Clitoris, labia majoramajora & vagina& vagina

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Dermatomes & Dermatomes & MyotomesMyotomes

DermatomeDermatome An area of the skin that provides An area of the skin that provides

sensory sensory imputimput from a pair of spinal from a pair of spinal nerves.nerves.

MyotomeMyotome All muscles innervated by motor All muscles innervated by motor

neurons from a single spinal segment. neurons from a single spinal segment. These usually underlie the dermatomes.These usually underlie the dermatomes.

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Spinal Nerve MnemonicSpinal Nerve Mnemonic

I ate one dozen live wives one Tuesday.I ate one dozen live wives one Tuesday.

31 letters for 31 spinal nerves31 letters for 31 spinal nerves 8 cervical 8 cervical 12 thoracic12 thoracic 5 lumbar5 lumbar 5 sacral5 sacral 1 1 coccygealcoccygeal

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Learning Objectives

Discuss the connective tissue coverings of the central nervous system (CNS) and the spaces and fluids surrrounding them

Discuss the enlargements, the conusmedularis and the cauda equina in relations to the spinal cord

Numbers of spinal nerves in each region Discuss each nerve plexus their

originations and the major nerves within each as well as what they innervate

Learning Objectives Discuss the cross-sectional anatomy of

the spinal cord as well as functional associations of each area

Describe the functional arrangement of the gray matter in the spinal cord

Describe the anatomy of spinal nerves and roots as well as the dorsal root ganglion

Discuss the components of a spinal reflex arc

Learning Objectives

List the different types of reflexes Describe the knee jerk reflex Define dermatomes and myotomes