Anatomy Spine2

8/6/2019 Anatomy Spine2

1/54

SPINAL CORD

PROF DR NASARUDDIN ABDUL AZIZ

Management & Science [email protected]


2/54

OBJECTIVES

describe the external structure of the spinalcord,

draw and describe the internal structure of

the spinal cord,

draw and describe the ascending and

descending tracts within the spinal cord,

describe the meninges surrounding the

spinal cord,

describe the blood supply of the spinal cord,

explain the clinical correlations of &

applications related to the spinal cord


3/54

Gross Appearance

Cylindrical in shape

Foramen magnum L1/L2 (adult)

L3 (newborn)

Occupies upper of vertebral canal

Surrounded by 3 layers of meniges:

dura mater

arachnoid mater

pia mater

CSF in subarachnoid space


4/54

Enlargements: cervical & lumbar

Conus medullaris

Filum termniale Anterior median fissure

Posterior median sulcus

31 pairs of spinal nerves attached to it bythe anterior roots & posterior roots


5/54


6/54


7/54


8/54


9/54


10/54


11/54

Structure Of The Spinal Cord


12/54


13/54


14/54

Gray Matter

H-shaped pillar with anterior& posterior gray

horns

United by gray commissure containing the

central canal Lateral gray column (horn) present in

thoracic & upper lumbar segments

Amount of gray matter related to the amountof muscle innervated

Consists of nerve cells, neuroglia, blood

vessels


15/54

Nerve cells in the anterior gray columns Large & multipolar

Axons pass out in the anterior nerve roots

as -efferents Smaller nerve cells are multipolar

Axons pass out in anterior roots as -

efferents


16/54

Nerve cells in the posterior gray columns 4 nerve cell groups

Substantia gelatinosa

situated at the apex throughout the length of spinal cord

composed mainly ofGolgi Type II neurons

receives afferent fibres concerning with pain,

temperature & touch from posterior root


17/54

Nucleus proprius anterior to substantia gelatinosa

present throughout the whole length of spinal

cord main bulk of cells in posterior gray column

receives fibers from posterior white column

that are assoc with proprioception, 2-point

discrimination & vibration


18/54

Nucleus dorsalis (Clarks column)

base of posterior column C8 L3 / L4

associated with proprioceptive endings

(neuromuscular spindles & tendon spindles)

Visceral afferent nucleus

lateral to nucleus dorsalis

T1 L3

receives visceral afferent info


19/54

Nerve cells in the lateral gray columns Formed by the intermediolateral group of

cells

T1 L2 / L3 Cells give rise to preganglionic

sympathetic fibres

In S2, S3, S4; they give rise topreganglionic parasympathetic fibres


20/54

The gray commissure & central canal connects the gray on each side

central canal in the centre

posterior gray commissure

anterior gray commissure

central canal present throughout

superiorly continuous with the central canal ofmedulla oblongata

inferiorly, expands as terminal ventricle

terminates within the root of filum terminale


21/54

White Matter

Divided into

anterior white column

lateral white column posterior white column

Consists of nerve fibres, neuroglia, blood

vessels

White due to myelinated fibres


22/54

Tracts

Ascending

Descending

Intersegmental


23/54

Ascending Tracts

Fibres that ascend from spinal cord to

higher centres

Conduct afferent information which may ormay not reach consciousness

Information may be

exteroceptive (pain, T, touch)

proprioceptive (from muscles & joints)


24/54

Organization

Ascending pathway that reach

consciousness consists of 3 neurons:

1st-order neuron

2nd-order neuron

3rd-order neuron

Branch to reticular formation

(wakefulness)

Branch to motor neurons (reflex activity)


25/54

Lateral spinothalamic tract pain & T

Anterior spinothalamic tract

light (crude) touch & pressure

Fasciculus cuneatus

Fasciculus gracilis

discriminatory touch, vibration, info from muscles &

joints Anterior spinocerebellar tract

Posterior spinocerebellar tract

unconscious info from muscles, joints, skin, subcut


26/54


27/54

Spinotectal tract

spinovisual reflexes

Spinoreticular tract info from muscles, joints & skin to reticular

formation

Spino-olivary tract

indirect pathway to cerebellum


28/54

Lateral spinothalamic tract

Pain & temp pathways

1st-order neurons

Pain conducted by A-type fibres & C-type

fibres

2nd-order neurons

decussate to the opposite side

ends in thalamus (ventral posterolateral nucleus 3rd-order neurons

ends in sensory area in postcentral gyrus


29/54

Anterior spinothalamic tracts

Light (crude) touch & pressure pathways


30/54

Posterior white column

Discriminative touch, vibratory sense,

conscious muscle joint sense (conscious

proprioception)


31/54

Posterior spinocerebellar tract

Muscle joint sense pathways tocerebellum

Unconscious proprioception

Muscle joint info from muscle spindles,GTO, joint receptors of the trunk & lowerlimbs

Info is used by the cerebellum in thecoordination of movements & maintenanceof posture


32/54

Anterior spinocerebellar tract

Majority of 2nd-order neurons cross to the

opposite side

Enter cerebellum through superiorcerebellar peduncle

Info from trunk, upper & lower limbs

Also carries info from skin & subcut tissue


33/54

Descending Tracts

Lower motor neurons

Upper motor neurons

Corticospinal tracts concerned with voluntary, discrete, skilled

movements


34/54


35/54

Reticulospinal tract facilitates or inhibits voluntary movement or reflex

activity

Tectospinal tract

reflex postural movements in response to visualstimuli

Rubrospinal tract

facilitates activity of flexor muscles & inhibitsactivity of extensor muscles

Vestibulospinal tract

facilitates extensor muscles, inhibits flexor

muscles


36/54

Meninges

Dura mater

Arachnoid mater

Pia mater


37/54


38/54

Dura mater

Dense, strong fibrous membrane

Encloses the spinal cord & cauda equina

Continuous above with meningeal layer ofdura covering the brain

Ends at the level of S2

Separated from wall of vertebral canal bythe extradural space

Contains loose areolar tissue & internal

vertebral venous space


39/54


40/54

Arachnoid mater

Delicate impermeable membrane

Lies between pia and dura mater

Separated from pia mater by subarachnoidspace

Continuous above with arachnoid mater

covering the brain Ends on filum terminale at level of S2


41/54

Pia mater

Vascular membrane

Closely covers spinal cord

Thickened on either side between nerveroots to form the ligamentum denticulatum


42/54

Blood supply

Arteries of the spinal cord

Anterior spinal artery

Posterior spinal artery Segmental spinal arteries


43/54


44/54

Anterior spinal artery

Formed by the union of 2 arteries

From vertebral artery

Supply anterior of spinal cord

Posterior spinal arteries

Arise from vertebral artery or posterior

inferior cerebellar arteries (PICA)

Descend close to the posterior roots

Supply posterior of spinal cord


45/54


46/54


47/54


48/54

Segmental spinal arteries

Branches of arteries outside the vertebralcolumn

Gives off the anterior & posterior radicular

arteries Great anterior medullary artery of

Adamkiewicz

Arise from lateral intercostal artery or

lumbar artery at any level from T8 L3


49/54


50/54


51/54


52/54

Clinical correlations

Spinal shock Follows acute severe damage to the spinal

cord

All cord functions below the level of thelesion become depressed or lost

Sensory impairment and flaccid paralysis

occur Segmental spinal reflexes are depressed

Persists for less than 24 hours (may be as

long as 1 4 weeks)


53/54

Poliomyelitis Acute viral infection of the neurones of

anterior gray column

Motor nuclei of cranial nerves Death of motor neurone cells paralysis

& wasting of muscles

Muscles of lower limb more often affected


54/54

Anatomy Spine2

Documents