ANATOMY OF ANATOMY OF SPINAL CORDSPINAL CORD

Dr. GURUDASANDr. GURUDASAN

INTRODUCTIONINTRODUCTIONSpinal cord is the

lower elongated part of the central nervous system

Cylindrical in shape

Slightly flattened anteroposteriorly

45cm in length30gm in weight

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EXTENSIONEXTENSIONFrom upper border of

first cervical vertebra to the lower border of first lumbar vertebra

Its lower tapering end is called as conus medullaris

Apex of the conus medullaris continues as a thin filament called filum terminale

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C1

L1

POSITIONAL CHANGES OF THE CORDPOSITIONAL CHANGES OF THE CORD

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POSITIONAL CHANGES POSITIONAL CHANGES (Contd…)(Contd…)

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3rd month (IU Life) – Spinal cord is as long as vertebral canal.

At birth – Spinal cord lies at L3

In adults – Spinal cord lies at lower border of L1.

REGIONS SPINAL SEGMENTS

VERTEBRAL LEVEL

GENERAL RULE

Upper cervical

C2 C2 Same level

Lower cervical

C6 C5 One verterbra above

Upper thoracic

T5 T3 Two vertebra above

Lower thoracic

T10 T7 Three vertebra above

Lumbar L1 – L5 T10 – T11 Three to five vertebra above

Sacral and coccygeal

S1 – S5 and CX 1

T12 – L1 Six to ten vertebra above

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SPINAL MENINGESSPINAL MENINGES

From outside inwards

Dura mater

Arachnoid mater

Pia mater

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Duramater

Arachnoid mater

Piamater

SPINAL DURAMATERSPINAL DURAMATERExtends from foramen

magnum to lower border of second sacral vertebra (S2)

The space between spinal dura and vertebral canal is called as epidural space

The space between duramater and arachnoid mater is called subdural space

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SPINAL DURA CRANIAL DURA

Single layer consists of meningeal layer alone

Does not form folds

Double layered. Consists of inner meningeal layer and outer endosteal layer

Forms dural folds viz. Falx cerebri, falx cerebelli, tentorium cerebelli, diaphragma sella

Epidural space present Epidural space absent

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ARACHNOID MATERARACHNOID MATER

Thin transparent, avascular membrane

Above it is continuous with the arachnoid mater of the brain

Below it extends upto the level of lower border of S2

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PIAMATERPIAMATERThin highly vascular

membraneContinues below the

spinal cord as filum terminale

The space between the pia mater and arachnoid mater is called as subarachnoid space and is filled with CSF

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LUMBAR CISTERNLUMBAR CISTERN

The subarachnoid space around the filum terminale becomes roomy forming a pool of CSF called lumbar cistern

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LUMBAR PUNCTURELUMBAR PUNCTURE It is done to

withdraw CSF for various diagnostic and therapeutic procedures.

Most preferred site: Interspinous space between L3 and L4.

LANDMARK: An imaginary line joining highest point on the iliac crest passes through the spine of L4.

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OBJECTIVES OF LUMBAR PUNCTUREOBJECTIVES OF LUMBAR PUNCTURE

To assess pressure of CSF

Biochemical investigation:Colour, cellular content, chemical composition.

• Drugs may also be injected

• SPINAL ANAESTHESIA:Anaesthetic drugs act on the lower spinal nerve roots and render the lower part of body insensitive to pain.

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LUMBAR PUNCTURE (CONTD...)LUMBAR PUNCTURE (CONTD...)Structures through

which the needle passes

I) SkinII) Superficial fasciaIII) Supraspinous ligamentIV) Interspinous ligamentV) Ligamentum flavumVI) Areolar tissue

containing internal vertebral venous plexus

VII) DuramaterVIII) Arachnoid mater

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MODIFICATIONS OF PIAMATERMODIFICATIONS OF PIAMATER

Filum terminale

Ligamenta

denticulata

Linea splendens

Subarachnoid

septum

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FILUM TERMINALEFILUM TERMINALEDelicate,white

thread like structureFrom tip of the

conus medullaris to the first coccygial vertebra

About 20cmFilum terminale

InternumFilum terminale

Externum

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SUBARACHNOID SUBARACHNOID SEPTUMSEPTUM

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Mid-sagittal fenestrated pial septum

Connects the dorsal surface of the spinal cord with the arachnoid mater

LINEA SPLENDENSLINEA SPLENDENS

Median glistening line,made up of pia mater

Located on the ventral surface along the anterior medin fissure

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LIGAMENTA DENTICULATALIGAMENTA DENTICULATATwo transparent

ribbon like thickened bands of pia mater

Extending laterally between anterior and posterior nerve roots

The lateral margin of each band presents 21 tooth like processes

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Ligamenta denticulate

EXTERNAL FEATURES OF THE SPINAL EXTERNAL FEATURES OF THE SPINAL CORDCORD

Fissure and sulci

Attachment of spinal nerves

Enlargements

Cauda equina

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FISSURES AND SULCIFISSURES AND SULCI

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Attachment of spinal Attachment of spinal nervesnerves

Thirty-one pairs of spinal nerves emerge from the sides of the cord

Cervical-8Thoracic-12Lumbar-5Sacral-5Coccygeal-1

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Attachment of spinal Attachment of spinal nervesnerves

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Dorsal root with ganglion

Ventral rootVentral rootlets

Dorsal rootlet

SPINAL SEGMENTSSPINAL SEGMENTSThe region of

spinal cord from where a pair of spinal nerves the emerge

But there is no actual surface indication of segmentation.

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ENLARGEMENTSENLARGEMENTS

Cervical

Lumbar

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CAUDA EQUINACAUDA EQUINAA large

subarachnoid space surrounds the filum terminale internum

It is the site of lumbar puncture for collection of CSF

Injection of drugs in to subarchnoid space

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INTERNAL STRUCTURE OF THE SPINAL INTERNAL STRUCTURE OF THE SPINAL CORDCORD

Has H shaped gray matter which consists of cell bodies of neurons and neuroglia

White matter surrounds the gray and consists of myelinated and unmyelinated nerve fibers with neuroglia

Gray matter has anterior column/ horn and posterior horn on each side

They are connected by gray commissure which contains central canal lined by ependyma

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INTERNAL STRUCTUREINTERNAL STRUCTUREWhite matter is divided

into two halves by anterior median fissure and posterior median septum

Each half is again divided in to anterior, lateral and posterior funiculi

Small strip of white matter connects the two halves in front of the gray commissure.This called the white or anterior commissure

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GREY MATERGREY MATERHas cell bodies of

multipolar neurons and interneurons (Renshaw cells)

It is divided in to three horns – anterior (motor)

Posterior (sensory)

Intermediolateral (visceral)

Anterior horn – neurons of the anterior horn are lower motor neurons

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SHAPE OF SPINAL CORD AT DIFFERENT LEVELSSHAPE OF SPINAL CORD AT DIFFERENT LEVELS

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NUCLEI AND LAMINAENUCLEI AND LAMINAE

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TRACTSTRACTS

Major Ascending tractsSpinothalamicFasciculus gracilisFasciculus cuneatusSpinocerebellarMajor Descending

tractsCortico spinalRubro spinalReticulo spinal

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BLOOD SUPPLYBLOOD SUPPLY

Anterior spinal artery

Two posterior spinal arteries

Segmental arteries

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BLOOD SUPPLY BLOOD SUPPLY ( contd...)( contd...)

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Venous drainage: Two median

longitudinal

Two anterolateral

Two posterolateral

Internal vertebral venous plexus

Basilar venous plexus

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CLINICAL ANATOMYCLINICAL ANATOMY

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LUMBAR DISC LUMBAR DISC HERNIATIONHERNIATION

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CLINICAL MANIFESTATION - IVDPCLINICAL MANIFESTATION - IVDP

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