03-4 Spinal Cord Paediatric Physio

7/30/2019 03-4 Spinal Cord Paediatric Physio

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SPINAL CORD ANATOMY


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SPINAL CORD ANATOMY

Spinal cord is covered by pia, arachnoid, and dura

Cord suspended in dural sheath by denticulate

ligament on each side

Attached along lateral surface of cord midway between

dorsal and ventral roots


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SPINALCORDANATOMY

Cord is enlarged in cervical (C4-T1) and

lumbosacral regions (L2-S3)

Cord contains grey matter, white matter tracts, and

central canal

Central canal lined by ependyma


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SPINALCORDANATOMY

Gray matter

Dorsal root entry zone

White matter

Vascular anatomy


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CROSS-SECTIONOFTHESPINALCORDWITH

LAMINAEOF REXED

.

From G. Paxinos & C. Watson


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LAMINAOF REXED

Gray matter of spinal cord divided into ventral(anterior) and posterior (dorsal) horns

Posterior horn contains laminae 1-6

Lamina 1 gives origin to the pathway relaying

information about pain to the thalamus Lamina 2 and 3 (substantia gelatinosa) functions in

regulating afferent input to the spinal cord.


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LAMINAOF REXED

Lamina 4 projects to the lateral cervical nucleus, theposterior column nuclei, and the thalamus(spinothalamic tract)

Lamina 5 and 6 receives proprioceptive input ANDsensory information relayed by lamina 4. These are the

sites of origin of ascending projections to higher centres. From T1 to L3 is Clarkes column, which is within lamina 6 and

contains projections to the cerebellum via the dorsalspinocerebellar tract


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LAMINAOF REXED

Anterior horn:

Lamina 9 contains motor neurons supplying the

limbs and lamina 9M contains motor neurons

supplying the trunk and neck. 9M is medial to 9.

Is further subdivided into flexor and extensors (flexors

are dorsal) and into distal and proximal (distal is more

lateral).


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LAMINAOF REXED

Laminae 7 and 8 contain interneuronsinvolved in motor control and motor neuronsthat project to brain. Lamina 8 is highly related to lamina 9M, and

participates in movements of muscles in thehead and neck.

Lamina 7 is related to lamina 9 and participatesin limb muscle movement

Lamina 8 and 9M are highly developed in highcervical and thoracic segments controlling neckand trunk, whereas laminae 7 and 9 are highlydeveloped in the spinal enlargements controllingthe arms and legs


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LAMINAOF REXED

Intermediolateral cell column is present in

thoracic and sacral segments, and is not

considered part of the anterior or posterior

hornContains neurons of origin of pre-ganglionic

autonomic fibres

Lamina 10 surrounds central canal, and

contains neurons that project to the opposite

side of the cord.


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NERVE PATHWAYSINTOTHE SPINAL

CORD sensorypathway

motor

pathway


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Somatic Sensory Pathway


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Ascending Spinal Cord Tract


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Ascending Spinal Cord Tract

1st order neuron-cutaneous receptors of

skin and proprioceptors spinal cord or

brain stem

2nd order neuron- to thalamus or

cerebellum

3rd order neuron- to somatosensory cortexof cerebrum

Conducts sensory impulses upward through

3 successive chains of neurons


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Descending Spinal Cord Tract


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WHITEMATTER

Divided into dorsal, lateral and ventral funiculi

Dorsal funiculus mostly comprised of ascendingfibres whose bodies are located in dorsal rootganglia

Fibres are ipsilateral Proprioception and fine discrimination (note that

vibration is carried in both dorsal and lateral funiculi)


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WHITEMATTERDORSALFUNICULUS

Fasciculus gracilis medial to fasciculuscuneatus

F. gracilis from lower limbs and cuneatus

from upper limbsNote that lowest segmental innervation is

most medial in gracilis and highestinnervation is most lateral in cuneatus

Nucleus gracilis and cuneatus in medullaThere are descending fibres in dorsal

funiculus which modify sensory input to thecord


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WHITEMATTERLATERALFUNICULUS

Dorsolateral and lateral parts (fasciculi)

Dorsolateral contains lateral corticospinaltract (axons from contralateral frontal and

parietal lobes); frontal fibres end in ventralhorn Lower limbs are lateral in tract and head is

medial

Distal muscles are posterior to proximal muscles

Rubrospinal tract (from contralateral rednucleus) is rudimentary in humans; involvedin increasing flexor tone


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LATERALFUNICULUS

Raphespinal tract in dorsal part of lateral funiculus;

modifies painful stimuli from dorsal horn; fibres may

begin in reticular formation of medulla

Hypothalamospinal tract arises from paraventricular

nucleus of hypothalamus and end in pre-ganglionic

autonomic segments T1-L3 and S2-S4


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LATERALFUNICULUS

spinocervical tract ascends and terminates

in lateral cervical nucleus, which is

rudimentary in humans (significance is

unknown)Dorsal spinocerebellar tract is present

above L3; arises from Clarkes column and

terminates in ipsilateral cerebellum; forms

part of pathway of conscious proprioceptionfrom lower limb


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LATERALFUNICULUS

Ventrolateral fasciculus

Spinothalamic tract has its nuclei in lamina4,5,6 mostly.

Axons cross midline in ventral white commissureand traverse the ventral horn

End in thalamus

Collateral branches to reticular formation

Pain and thermal sensations

Fibres from lower limb are most superficial andfrom upper limb are deepest


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LATERALFUNICULUS

Ventral spinocerebellar tract arises from dorsal hornand border cells of ventral horn of lumbosacralcord

Crossed fibres

Ascends to midbrain, enters superior cerebellarpeduncle, and decussates again, and enterscerebellar cortex

Concerned with proprioception


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LATERALFUNICULUS

Spinotectal tract fibres from same part as

spinothalamic tract end in superior colliculus and

reticular formation (fibres are crossed

Spinoreticular tract originates in laminae 4-8 ends

in reticular formation; is important in perception of

pain and other modalities originating in internal

organs


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LATERALFUNICULUS

Spino-olivary tract has uncertain role in humans

Ventrolateral fasciculus also contains descending

medullary reticulospinal tract, which controls motor

activities that do not require conscious effort


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VENTRALFUNICULUS

Ventral corticospinal tract contains uncrossed fibres

Vestibulospinal tract is uncrossed pathway from the

lateral vestibular nucleus of medulla; axons

terminate in lamina 8

Mediates reflexes of equilibrium


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VENTRALFUNICULUS

Pontine reticulospinal tract

Medial longitudinal fasciculus (only in cord to upper

cervical levels) is involved in movements of head

required for equilibrium

Tectospinal tract from contralateral superior

colliculus


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FASCICULUSPROPRIUS

Present in all funiculi immediately adjacent to gray

matter

Contains propriospinal fibres which connect

different segmental levels of gray matter

Ascend and descend variable lengths and provide

functional equivalent of interneurons


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DORSALROOTENTRYZONE

Each dorsal root branches into 6-8 rootlets

Axons segregated into two divisions within eachrootlet: lateral and medial

Lateral contains unmyelinated (type C) fibres and

enters dorsolateral tract of Lissauer Medial contains larger, myelinated axons, and enter

white matter medial to dorsal horn


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VASCULARANATOMY - ARTERIAL

Cord is supplied by multiple radicular

arteries, which form the anterior and

posterior spinal artery

Radicular arteries arise from adjacentarteries at each vertebral segment

Pass through intervertebral foramina to supply

nerve roots, but most do not reach the cord

Larger radicular arteries which also supplycord are called radiculomedullary arteries


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VASCULARANATOMY -ARTERIAL

Anterior spinal artery originates in upper cervicalregion, from anterior spinal branches of vertebralartery.

6-10 anterior radicular arteries contribute to it

throughout its length. Supplies anterior two thirds of cord, via central

branches and penetrating branches of pial plexus


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VASCULARANATOMYARTERIALTERRITORIES

Cervical and first two thoracic segments of

cord are supplied by radicular Arteries, that

arise from subclavian artery.

mid-dorsal region of cord (T3-T7) issupplied from radicular artery

accompanying T4 or T5 root

T8 to conus supplied by largest anterior s

segmental medullary artery

Other name Adamkiewicz


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VASCULARANATOMY - ADAMKIEWICZ

Arises from left sided lumbar (segmental) artery in80%

85% reaches cord between T9-L2; 15% between

T3-T8 (in these cases it is supplemented by aradicular artery arising more inferiorly)

Has large anterior and small posterior branch Anterior branch ascends, then gives off a small

ascending branch and larger descending branch Descending branch goes inferior (to conus) and makes

an anastomotic loop with posterior spinal artery


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VASCULARANATOMYARTERIAL

Cauda equina also supplied by branches from

lumbar, iliolumbar, and lateral and median sacral

artery.


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VASCULARANATOMYPOSTERIORSPINAL

ARTERY

Paired arteries

Run along posterolateral cord

Sometimes discontinuous

Originates from verterbral artery Has contribution from 10-23 posterior radicular

artery.

Supplies posterior one third of cord


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VASCULARANATOMY

Anterior spinal a. gives off central branchesand branches to pial plexus

Central branches run in anterior medianfissure and supply central cord

Pial plexus is formed from both anterior andposterior spinal a. Give penetrating branches which supply outer

cord

Some overlap between supply of centraland pial branches


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VASCULARANATOMY - VENOUS

Internal and external vertebral venous plexuses

Form rings around each vertebra

Freely anastomose with each other


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External plexus has anterior part (anterior to

vertebral body) and posterior part (over posterior

elements including laminae and spinous processes)

Anterior and posterior parts freely anastomose


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Internal plexus: anterior part is on each side of PLL,

posterior to vertebral body; posterior part is interior

to ligamentum flavum

Vertebral body drained by basivertebral veins which

enter anterior external plexus


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Veins of cord mirror related arteries indistribution

Venules drain into anterior and posteriorveins, which drain into two medianlongitudinal veins, and into anterolateral andposterolateral longitudinal veins lyingadjacent to the nerve roots

Radicular veins join branches from internalplexus forming intervertebral veins (havevalves), which exit intervertebral foraminaand join their respective segmental veins

03-4 Spinal Cord Paediatric Physio

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