spinal cordspinal cord

Spinal cordSpinal cordOrigin:Origin:

foramen megnum continous with foramen megnum continous with medulla oblongata of brainmedulla oblongata of brain

TerminationTermination in adultin adult

at the lower boarder of L1at the lower boarder of L1

in childin child at the upper boarder of L3 at the upper boarder of L3

MeningsMeningsThe spinal cord is surrounded by three membranesThe spinal cord is surrounded by three membranes

11 dura materdura mater2 :arachnoid mater2 :arachnoid mater3:pia mater3:pia mater : :

Function’Function’ProtectionProtection Also by cerebrospinal fluid present in the subarachnoid spaceAlso by cerebrospinal fluid present in the subarachnoid space

In the cervical regionIn the cervical region it gives origin to the brachial plexus it gives origin to the brachial plexus lower thoracic region and lumber lower thoracic region and lumber

regionregion it gives origin to lumbosacral plexus .it gives origin to lumbosacral plexus .

superiorlysuperiorly the spinal cord is fusiformly enlarge the enlargement the spinal cord is fusiformly enlarge the enlargement

is referred as the cervical and lumber enlargement is referred as the cervical and lumber enlargement

inferiorly inferiorly the spinal cord tapers off into the conus medullaris the spinal cord tapers off into the conus medullaris

from the apex of which a prolongation of pia mater from the apex of which a prolongation of pia mater the filum terminale descend to be attached to the the filum terminale descend to be attached to the posterior surface of the coccyx. posterior surface of the coccyx.

locationlocation The cord lie in midlineThe cord lie in midline anterior median fissure anterior median fissure posterior median sulcus.posterior median sulcus. Along the entire length of the spinal cord are Along the entire length of the spinal cord are

attached 31 no of spinal nerves by theattached 31 no of spinal nerves by the anterior or motor roots andanterior or motor roots and Posterior root or sensoryPosterior root or sensory posterior root ganglionposterior root ganglion cells which gives rise to peripheral and center cells which gives rise to peripheral and center

nerve fibbernerve fibber

Structure of spinal cordStructure of spinal cord

gray matergray mater innerinner white materwhite mater

OuterOuter GRAY MATERGRAY MATER On croos section the gray mater is seenOn croos section the gray mater is seen H-shapedH-shaped pillar with pillar with anterioranterior column or hornscolumn or horns

posterior column or hornsposterior column or horns

lateral gray column or horn (THORACIC AND lateral gray column or horn (THORACIC AND LUMBER)LUMBER)

united byunited by

gray commissure gray commissure With central canalWith central canal

Nerves cell groups in the anterior Nerves cell groups in the anterior gray columngray column

Alpha efferent Alpha efferent nervenerve

large large MultipolarMultipolar It innervates the skeletal It innervates the skeletal

musclemuscle Axon pass out in Axon pass out in

anterior roots of spinal anterior roots of spinal nervesnerves

Gamma efferentGamma efferent

SmallSmall MultipolarMultipolar It innervates intrafusal It innervates intrafusal

muscle fibers of muscle fibers of neuromuscular spindlesneuromuscular spindles

Axon may pass out in Axon may pass out in anterior roots of the anterior roots of the spinal nerves spinal nerves

Nerve cell of the anterior gray column Nerve cell of the anterior gray column is divided into three basic groupsis divided into three basic groups

(1) MEDIAL GROUP(1) MEDIAL GROUP (2) CENTRAL GROUP(2) CENTRAL GROUP (3) LATERAL GROUP(3) LATERAL GROUP

Medial groupMedial groupEXTENTIONEXTENTION WHOLE SPINAL CORDWHOLE SPINAL CORD innervate innervate muscle of muscle of neck, neck, trunk, trunk, intercostal intercostal abdominalabdominal

(2)Central group:(2)Central group:

EXTENTIONEXTENTION cervical, lumber, sacral segmentscervical, lumber, sacral segments

Three nucleiThree nuclei (a) (a) phrenic nucleusphrenic nucleus(C(C3’4’5)3’4’5)

INERVATEINERVATE DIAGHPHRAMDIAGHPHRAM

(b)(b)accessory nucleusaccessory nucleus) ) (C(C5 OR 6)5 OR 6)

INNERVATIONINNERVATION sternocliedomastoid and trapezius musclesternocliedomastoid and trapezius muscle

(c) lumbosacral nucleus (c) lumbosacral nucleus (L2 TO S1)(L2 TO S1)INNERVATIONINNERVATION unknwon distributionunknwon distribution

Lateral groupLateral group

ExtentionExtention cervical and lumbosacral segmentcervical and lumbosacral segment InnervationInnervation MusclesMuscles (1) upper limb(1) upper limb (2) lower limb(2) lower limb

Nerve cells of the posterior gray Nerve cells of the posterior gray columncolumn

four nerve cell groupfour nerve cell group 1 substantia gelatinosa1 substantia gelatinosa 2 nucleus propius2 nucleus propius 3 nucleus dorsalis (clarks column)3 nucleus dorsalis (clarks column) 4 visceral afferent nucleus4 visceral afferent nucleus First twoFirst two extention extention through out the length of the cord through out the length of the cord other two other two extentionextention lumber and thoracic segmentslumber and thoracic segments

Substantia gelatinosaSubstantia gelatinosa

locationlocation apex of the posterior gray column apex of the posterior gray column composed composed Golgi type 2 neuronGolgi type 2 neuron functionfunction receives afferent fiber associated withreceives afferent fiber associated with pain , pain , temperature temperature touch. touch. Furthermore it receive input from the descending Furthermore it receive input from the descending

fibers from the supraspinal level . fibers from the supraspinal level .

Nucleus propiusNucleus propius

LocationLocation Below s gBelow s g FunctionFunction senses of senses of position position movement (proprioception)movement (proprioception) two points discrimination two points discrimination vibrationvibration

Nucleus dorsalisNucleus dorsalis

LocationLocation base of the posterior gray column base of the posterior gray column extending extending CC8 to 8 to LL3 43 4 FUNCTIONFUNCTION proprioceptive endingsproprioceptive endings

neuromuscular spindles and tendon neuromuscular spindles and tendon spindle spindle

Visceral afferent nucleusVisceral afferent nucleus

LOCATIONLOCATION lateral to the nucleus dorsalislateral to the nucleus dorsalis EXTENTIONEXTENTION TT11 toto L L22

FUNCTIONFUNCTION receiving visceral afferent information receiving visceral afferent information

Nerve cell group lateral gray columnNerve cell group lateral gray column

ExtendExtend TT11 TO S TO S44

CellsCells T1 TO L3T1 TO L3 preganglionic sympathetic nerve fiberpreganglionic sympathetic nerve fiber CELLSCELLS S 2,3,4S 2,3,4 preganglionic parasympathetic preganglionic parasympathetic

fiberfiber

The gray commissure and central The gray commissure and central canalcanal

LOCATIONLOCATION the anterior and posterior gray columns on each side are connected the anterior and posterior gray columns on each side are connected

by a transverse gray commissure so that the gray column r in the by a transverse gray commissure so that the gray column r in the central of the gray commissure is situated central canal.central of the gray commissure is situated central canal.

SuperiorlySuperiorly above this it open into the cavity of the fourth ventricleabove this it open into the cavity of the fourth ventricle continuous with the central canal of the caudal half of the medulla continuous with the central canal of the caudal half of the medulla

oblongataoblongata

InferiorlyInferiorly It is closedIt is closed conus medullaris it expend into the fusiform terminal ventricleconus medullaris it expend into the fusiform terminal ventricle terminate below with in the root of the filum terminaleterminate below with in the root of the filum terminale It is filled with cerebrospinal fluid and is lined with epithelium called It is filled with cerebrospinal fluid and is lined with epithelium called

the ependyma the ependyma

IT resembles letter HIT resembles letter H posterior gray commissureposterior gray commissure The part of the gray commissure that is The part of the gray commissure that is

situated posterior gray canalsituated posterior gray canal

Anterior gray commisureAnterior gray commisure lie anterior to the canallie anterior to the canal

White materWhite mater It is divided into It is divided into anterior lateral anterior lateral posterior white columns or finiculi. posterior white columns or finiculi.

anterior columnanterior column locationlocation lie on each side lie in between the midline and the point of emergence lie on each side lie in between the midline and the point of emergence

of the anterior nerve root .of the anterior nerve root .

lateral columnlateral column locationlocation between the emergence of the anterior nerve root and the entry of the between the emergence of the anterior nerve root and the entry of the

posterior nerve root the posterior nerve root the

posterior columnposterior column locationlocation in between the entry of posterior nerve root and midline in between the entry of posterior nerve root and midline

Structure Structure

compositioncomposition in centrral nervous system the white mater of spinal in centrral nervous system the white mater of spinal

cord consist of a mixture of cord consist of a mixture of nerve fibernerve fiber neuroglia neuroglia blood vessel blood vessel it surrounds the gray mater it surrounds the gray mater its white color is due to the high proportion of its white color is due to the high proportion of

myelinated nerve fibermyelinated nerve fiber

Blood Supply of the Spinal CordBlood Supply of the Spinal Cord The spinal cord receives its arterial supply from three The spinal cord receives its arterial supply from three

small, longitudinally running arteries: small, longitudinally running arteries: the two the two posterior spinal arteries posterior spinal arteries and and one anterior spinal one anterior spinal artery. artery. The posterior spinal arteries, which arise The posterior spinal arteries, which arise either directly or indirectly from the vertebral arteries, either directly or indirectly from the vertebral arteries, run down the side of the spinal cord, close to the run down the side of the spinal cord, close to the attachments of the posterior spinal nerve roots. The attachments of the posterior spinal nerve roots. The anterior spinal arteries, which arise from the vertebral anterior spinal arteries, which arise from the vertebral arteries, unite to form a single artery, which runs arteries, unite to form a single artery, which runs down within the anterior median fissure.down within the anterior median fissure.

The posterior and anterior spinal arteries are The posterior and anterior spinal arteries are reinforced by radicular arteriesreinforced by radicular arteries, which enter the , which enter the vertebral canal through the intervertebral foramina.vertebral canal through the intervertebral foramina.

The veins The veins of the spinal cord drain into the internal of the spinal cord drain into the internal vertebral venous plexus.vertebral venous plexus.