Spinal Cord Spinal Cord

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Spinal Cord Spinal Cord

Prof. Dr. Selda Önderoğlu

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 Foramen magnumForamen magnum

 Extends caudally in the vertebral Extends caudally in the vertebral canal

canal

 Termination: L3 (newborn), Termination: L3 (newborn), L1 lower border (adult)

L1 lower border (adult)

 Longer in males than females, Longer in males than females, males about 45 cm

males about 45 cm

 Superiorly; continuous with Superiorly; continuous with medulla oblongata

medulla oblongata

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Spinal cord

Medulla oblongata

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Enlargements of spinal cord Enlargements of spinal cord

 Cervical Cervical ((bw.bw.C3–T2 segments)C3–T2 segments) – Spinal nn. forming the Spinal nn. forming the

brachial plexus brachial plexus

– Diameter, about 38 mmDiameter, about 38 mm

 LumbLumbarar

((bw.bw. L1–S3 segments)L1–S3 segments) – Spinal nn. forming the Spinal nn. forming the

lumbosacral plexus lumbosacral plexus

– Diameter, about 35 mmDiameter, about 35 mm – After this enlargement SC After this enlargement SC

becomes thin and forms becomes thin and forms conus medullaris

conus medullaris

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Conus medullaris Conus medullaris

 Spinal cord narrows Spinal cord narrows beginning from the beginning from the

inferior limit of inferior limit of

lumbosacral lumbosacral enlargement enlargement

 Conus medullaris; Conus medullaris;

termination of spinal termination of spinal cordcord

L1-L3

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Meninges of spinal cord Meninges of spinal cord



The membranes surrounding the The membranes surrounding the spinal cord

spinal cord



Continuation of meninges of brain Continuation of meninges of brain 3 in number:

3 in number:



Dura mater spinalis Dura mater spinalis



Arachnoidea mater spinalis Arachnoidea mater spinalis



Pia mater spinalis Pia mater spinalis



Pia mater terminates (closes) at the Pia mater terminates (closes) at the inferior limit of spinal cord

inferior limit of spinal cord (L1) (L1)



Dura mater and arachnoid Dura mater and arachnoid mater mater terminates (closes) at

terminates (closes) at S2 level

S2 level

Pia

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Denticulate ligament Denticulate ligament

 Spinal cord is suspended in dural Spinal cord is suspended in dural sac by

sac by denticulate ligament on denticulate ligament on each side

each side

 It is the It is the Extension of external Extension of external lamina of pia mater

lamina of pia mater

 With arachnoid mater attaches With arachnoid mater attaches inner surface of dural sac

inner surface of dural sac

 Uppermost part: Attaches occipital Uppermost part: Attaches occipital dura inside foramen magnum

dura inside foramen magnum

 20 - 22 processes20 - 22 processes

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Filum terminale Filum terminale

 After the closure of pia mater, After the closure of pia mater, beginning from this level, a beginning from this level, a

filament of connective tissue filament of connective tissue

(about 20 cm) descends from (about 20 cm) descends from

apex of conus medullaris apex of conus medullaris

 Filum terminale internum:

Its upper 15 cm, surrounded by Its upper 15 cm, surrounded by

extensions of dural and extensions of dural and

arachnoid meninges, reaches arachnoid meninges, reaches

caudal border of S2 vertebra caudal border of S2 vertebra

 Filum terminale externum (lig. Coccygeum

(lig. Coccygeum,,

dural part of filum terminale dural part of filum terminale):):

Final 5 cm, fuses with investing Final 5 cm, fuses with investing

dura mater, descends to dura mater, descends to dorsum of 1st coccygeal dorsum of 1st coccygeal

vertebral segment vertebral segment

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External features External features

of spinal cord of spinal cord

 Anterior median fissureAnterior median fissure

 Posterior median sulcusPosterior median sulcus

 Anterolateral sulcusAnterolateral sulcus

 Posterolateral sulcusPosterolateral sulcus

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A spinal cord segment A spinal cord segment

 Is the part of SIs the part of Spinal pinal CordCord from where a pair from where a pair of Spinal of Spinal NNerveserves

arise

arise;one from right ;one from right

&one from left side

 There are There are 31 segments31 segments of spinal cord

of spinal cord

 8 in cervical region8 in cervical region

 12 in thora12 in thoracic regioncic region

 5 in lumbar region5 in lumbar region

 5 in sacral region5 in sacral region

 1 in coccygeal region1 in coccygeal region

 31 pairs of SPINAL 31 pairs of SPINAL NERVES

NERVES

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Spinal nn.

 Posterior root; Posterior root;

enters spinal cord from enters spinal cord from

posterolateral sulcus, posterolateral sulcus,

brings sensory information brings sensory information

from periphery from periphery

 Anterior root; Anterior root;

leaves spinal cord from leaves spinal cord from

anterolateral sulcus, motor anterolateral sulcus, motor

 Fila radicularia (rootlets); the Fila radicularia (rootlets); the fibres forming the anterior and fibres forming the anterior and

posterior roots posterior roots

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Spinal n.:

31 pairs

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 Spinal cord is located in the vertebral Spinal cord is located in the vertebral canal

canal

 Spinal nerves leave the vertebral canal Spinal nerves leave the vertebral canal by passing through the intervertebral by passing through the intervertebral

foramen foramen

why there are 8 pairs of spin. Nn. At why there are 8 pairs of spin. Nn. At cervical level?? because

cervical level?? because

 C1C1 spinal nerve (suboccipital n. spinal nerve (suboccipital n.) leaves ) leaves vertebral canal bw.:

vertebral canal bw.: atlas – occipital atlas – occipital bone

bone

 cervical spinal nn. leave the vertebral cervical spinal nn. leave the vertebral canal just

canal just superiorsuperior to the intervertebral to the intervertebral foramen of its corresponding vertebra foramen of its corresponding vertebra

 The rest of the spinal nnThe rest of the spinal nn. leave the . leave the vertebral canal just

vertebral canal just inferior to the inferior to the intervertebral foramen of its

intervertebral foramen of its corresponding vertebra

corresponding vertebra

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Cauda equina Cauda equina

 Spinal cord is Spinal cord is shorter than shorter than

vertebral column vertebral column

 More caudal spinal More caudal spinal roots descend and roots descend and

course a long course a long

distance around distance around

the spinal cord to the spinal cord to

reach their reach their

corresponding corresponding

foramina foramina

 Thus; they form Thus; they form sheaf of spinal sheaf of spinal

nerve roots, distal nerve roots, distal to the apex of the to the apex of the

cord, called as cord, called as

cauda equina cauda equina

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dermatome, axial line dermatome, axial line

 Dermatome: Skin region Dermatome: Skin region innervated by a spinal n.

innervated by a spinal n.

 Axial line: In some regions; Axial line: In some regions;

the nn. innervating the two the nn. innervating the two neighbouring dermatome neighbouring dermatome

areas do not originate from areas do not originate from the neighbouring segments.

the neighbouring segments.

 Line between this type of  Line between this type of two dermatome regions

two dermatome regions

 By the axial line; n. fibres By the axial line; n. fibres innervating the two

innervating the two

neighbouring dermatomes neighbouring dermatomes

do not pass to each other do not pass to each other

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Internal structure of spinal cord Internal structure of spinal cord

 Gray matter: Gray matter:

contains Neurons, contains Neurons, neuroglia and blood neuroglia and blood vessels

vessels

Butterfly shaped Butterfly shaped

 White matter: White matter: contains Nerve contains Nerve fibres (mostly fibres (mostly

myelinated axons), myelinated axons), neuroglia, blood neuroglia, blood vessels

vessels

– Anterior Anterior funiculus funiculus – Posterior Posterior

funiculus funiculus

– Lateral funiculusLateral funiculus

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Gray matter has:

 Anterior hornAnterior horn

 Posterior hornPosterior horn

 Lateral horn (bw.T1 – L3 (L2)Lateral horn (bw.T1 – L3 (L2)

 In the examination of spinal In the examination of spinal cord

cord 3-dimensionally; anterior 3-dimensionally; anterior column, posterior column, column, posterior column,

lateral column (columna lateral column (columna

intermedia) intermedia)

 Central canal (contains Central canal (contains Cerebrospinal Fluid) Cerebrospinal Fluid)

ant.&post to central canal:

 Anterior gray commissureAnterior gray commissure

 Posterior gray commissurePosterior gray commissure

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Central canal Central canal

 Traverses whole spinal cord Traverses whole spinal cord and caudal half of medulla and caudal half of medulla

oblongata oblongata

 Opens above into 4th ventricleOpens above into 4th ventricle

 In the conus medullaris, it In the conus medullaris, it

expands as a fusiform terminal expands as a fusiform terminal

ventricle ventricle

 Extends for 5-6 mm into filum Extends for 5-6 mm into filum terminale

terminale

 CSFCSF

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internal structure of spinal cord at

different segments

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Laminae of the gray matter Laminae of the gray matter



10 laminae 10 laminae



Depending upon to Depending upon to dimension, shape, dimension, shape,

cellular cellular

characteristics, characteristics,

density of neurons

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

Laminae I – IV(post. horn): are related to sensory pathways (afferent pathways)

Lamina IX (ant. Horn): contains

Alpha motor neurons Gamma motor neurons Interneurons

Related to motor pathways (efferent pathways)

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White matter White matter

 Formed by axonsFormed by axons located in:

located in:

 Posterior funiculusPosterior funiculus

 Lateral funiculusLateral funiculus

 Anterior funiculusAnterior funiculus

 Posterior funiculus; in Posterior funiculus; in cervical and upper cervical and upper thoracic segments, by thoracic segments, by postero-intermediate postero-intermediate sulcus; divided into sulcus; divided into

fasciculus gracilis (medial) fasciculus gracilis (medial) and fasciculus cuneatus and fasciculus cuneatus (lateral)

(lateral)

 Anterior white commissureAnterior white commissure

 Posterior white Posterior white commissure commissure

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SPINAL REFLEX

Fibers coming from receptors in the muscles, joints and skin reach to the post horn neurons

They do not reach the cortical areas

Fibers directly arise from alfa motor

neurons (lamina IX) and form involuntary movements

Eg. You touch to fire than pull your hand immidiately

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Aa. of spinal cord Aa. of spinal cord

 Located Located In the In the

subarachnoidal space subarachnoidal space

 Vertebral aa. Vertebral aa.

 Radicular aa. Radicular aa.

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Vertebral a.

 Is a Branch of subclavian a.Is a Branch of subclavian a.

 Passes through foramina of Passes through foramina of all cervical transverse

all cervical transverse processes, except 7th processes, except 7th

 Enters cranium via foramen Enters cranium via foramen magnum

magnum

 Posterior spinal a. (2 in Posterior spinal a. (2 in number)

number)

 Anterior spinal a. (1 in Anterior spinal a. (1 in number)

number)

– 2 anterior spinal aa. unite 2 anterior spinal aa. unite anterior to pyramids;

anterior to pyramids;

form single anterior form single anterior spinal a.

spinal a.

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2 vertebral aa unit and form basilar artery

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in the ant median fissure

Courses the anterior

spinal

artery

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Spinal brc

Spinal brc of of neighboring neighboring aa during the course of

aa during the course of spinal cord

spinal cord

These aa. Are the:

- - Ascending cervical a. Ascending cervical a.

- - Deep cervical a. Deep cervical a.

-Intercostal aa. - Intercostal aa.

- - Lumbar aa. Lumbar aa.

-Lateral s

-Lateral s acral aa. acral aa.

Radicular aa

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Spinal branches Spinal branches Course along Course along spinal nn.

spinal nn.

Pass through Pass through intervertebral intervertebral foramina

foramina

Divide into Divide into: : anterior and anterior and posterior

posterior radicular aa.

radicular aa.

Anastamos Anastamose e with spinal aa with spinal aa and form arterial and form arterial vasocorona

vasocorona

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Artery of Adamkiewicz Artery of Adamkiewicz

 In the lumbar region, on In the lumbar region, on the left side, one of the the left side, one of the

anterior radicular branches anterior radicular branches

has a greater caliber than has a greater caliber than

the others the others

 A. radicularis magnaA. radicularis magna

 On the left side of spinal On the left side of spinal cord, supplies blood to cord, supplies blood to

lower thoracic and upper lower thoracic and upper

lumbar regions (main lumbar regions (main

artery) artery)

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Vv. of spinal cord Vv. of spinal cord

 Anterior spinal v.Anterior spinal v.

 Posterior spinal v.Posterior spinal v.

 By these 2 vv., drain into By these 2 vv., drain into smaller caliber vv. in

smaller caliber vv. in

anterolat and posterolat eral anterolat and posterolat eral

sulci sulci

 Venous vasocoronaVenous vasocorona

 These vv. unite and drain These vv. unite and drain into ant and post radicular into ant and post radicular vv.vv.

 Ant, post radicular vv. Ant, post radicular vv.  ant  ant and post internal vertebral and post internal vertebral venous plexuses (epidural venous plexuses (epidural

venous plexus) venous plexus)

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Connections of epidural venous plexus Connections of epidural venous plexus

 Thoracal vv.Thoracal vv.

 Abdominal vv.Abdominal vv.

 Intercostal vv.Intercostal vv.

 Ant external vertebral Ant external vertebral venous plexus

venous plexus

 Post external vertebral Post external vertebral venous plexus

venous plexus

 Prostatic venous plexusProstatic venous plexus

 Pelvic venous plexusPelvic venous plexus

 In the level of foramen In the level of foramen magnum, ant and post magnum, ant and post

internal vertebral venous internal vertebral venous plexuses gave branches, plexuses gave branches,

which connect with vertebral which connect with vertebral

v., sigmoid sinus, occipital v., sigmoid sinus, occipital

sinus sinus

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