Univerzita Karlova v Praze – 1. lékařská fakulta
spinal cord - structure, pathways
meninges and vessels
Anatomical institute
Autor: Ivo Klepacek
Obor: general medicine and dentistry
C1
Spinal Cord – General
Features
Intumescentia
cervicalis
Posterior Median Sulcus
C4 Th2
D
2-D Sections and
Spinal
cordnuclei
C1-Co4
3-D Structure :
White
and
Grey
Matter
Intumescentia
lumbalis
L2 S3
Th10 L2
V
Grey horns and
columns
White funiculi :
Dorsal, Lateral
and Ventral
Anterior Median Fissure
http://www.br
ain.riken.go.j
p/english/b_r
ear/b4_lob/im
ages/k_mikos
hiba_l1.gif
http://www.brain.rike
n.go.jp/english/b_rear/
b4_lob/images/k_mik
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Spinal cord-segment
homes.bio.psu.edu
The dorsal spinal cord, medulla spinalis
The spinal cord begins at the edge of the foramen magnum. decussatio
pyramidum separates it from the medulla oblongata and ends with a
rounded end, conus medullaris.
From there, it extends filum terminale, consisting of neuroglia and
connective tissue pia mater, which continues to saccus of DURA mater,
to which is fastened at the level of S2.
Two spinal cord thickening are visible, intumescentia cervicalis et
intumescentia lumbalis, sending the motor neurons to muscles of the
limbs.
Median anterior fissure is on the whole length of the spinal cordventrally
back in the midline there is shallower groove, posterior median sulcus.
The sides of the spinal cord we find 2 longitudinal grooves:
anterolateral one resign root fibers, fila radicularia forming the front
spinal root, radix anterior and posterolateral groove back root, radix
posterior.
The rear -roots level in the intervertebral
foramen ganglion spinale , conditional pseudounipolar sensitive neurons whose axons
enter back into the roots of the spinal cord.
Positions of spinal cord segments and their topographic relations to
vertebrae
Posterior sulcus
Anterior sulcus
Ventrolateral sulcus
Dorsal root
Pia mater
Ventral root
Arachnoid
Dural sleeve
Dural sac
Endorhachis
Spatium epidurale
Dura mater spinalis
Spatium subdurale
Arachnoidea spinalis
Spatium subarachnoidale
- Liquor cerebrospinalis
Pia mater spinalis
Canalis vertebralis (vertebral canal) extends from the foramen
magnum to sacral hiatus.
In the cervical and lumbar portion has a triangular shape; in the thoracic
levels is oval and sacral canal is ventrodorsally flattened.
Front border - the vertebral body and intervertebral disc , + lig.
longitudinale posterius;
rear border - the vertebral arches, the laminae and lig. Interarcualia
(flava); at the level of the S4 spinal canal opens into the sacral hiatus .
Spinal canal opens to the sides as foramina intervertebralia .
You perform spinal nerves and spinal cord along them to come the
closest arteries - rr. spinales which are divided into front and rear
radicular branches.
Spinal canal contains the spinal cord covered with meningeal
membranes.
The spinal cord ends at the level of the intervertebral disc L1- L2. Inside
sacral canal there are caudal spinal roots (horse tail, cauda equina) and
filum terminale.
Lumbal punction
uchospitals.edu
Subarachnoid space Spatium subarachnoideum, between the
arachnoid and pia mater is filled by cerebrospinal fluid. Arachnoidea
extends along the nerves to the spinal dural root sheaths and its neurothel
transferred to the peripheral nerves as perineural epithelium.
Pia mater adheres to the surface of the spinal cord. From the pia
mater to the arachnoid withdraws between the front and rear lateral roots
20-23 cípovitých processes of tissue that make up the leagues.
denticulatum. Ligg. denticulata fix the spinal cord in the spinal canal
during movements of the spine.
The epidural space of the spinal canal is the place in which it is
possible to apply local anastetika that through the dural root sheaths
penetrate to the roots of the spinal cord (epidural analgesia).
Vertebromedullary topography
Mutual relationship of vertebral
bodies and spinal cord segments is
shown in table
Vertebral body
C1 - C4
C5 - C6
C7 - Th8
Th9 - Th10
Th11
Th12 - L1
L2
Spinal segment
C1 - C4
C5 - C7
C8 - Th11
Th12 – L3
L4 – L5
S1 – S5
Co
Lumbal puncture L3/4 L4/5
Dermatoms -
Head zones
liver
stomach
kidney
Henry Head
1861-1940
1/3
2/3
Spinal cord is supplied by spinal arteries coming from the branches of the
subclavian artery and the descending aorta (aa. intercostales posteriores ,
aa . lumbales , a iliolumbalis , aa . sacrales laterales).
They enter into the spinal canal through the foramen intervertebralia .
Another source in the cranial part are direct branches of the intracranial
vertebral aa. entering the spinal canal through the foramen magnum .
Spinal arteries send branches to the walls of the spinal canal (postcentral and
prelaminar branches) , and second, radicular branches (a. radicularis anterior
and posterior ) reaching the spinal cord as aa. medullares segmentales.
They are initially formed along each of the spinal nerve (31 pairs) , but still
during prenatal development, when the spine is growing faster than the spinal
cord, the number of branches that reach the spinal cord is reduced so is not
retained in each segment. The remaining branches supply only spinal roots , spinal
cord covers and wall of the spinal canal .
Number and location of aa. medullares segmentales ( aa.
radiculomedullares anteriores et posteriores ) is highly
variable and it is not possible to formulate generally applicable
scheme of arrangement .
Spinal cord veins
F. H. Netter: Anatomický atlas člověka. Grada/Avicenum, Praha, 2003
columns
funiculi
White matter is formed by
fasciculi of fibers. Bundles of fibers
with the same course are grouped to
´tract fields´.
In that fields there is possible to
specify somatotopic projection and
spatial organization following
quality of sensations.
Gray matter, substantia grisea forms anterior horns
(columns, cornua), side corners - lateral horns (columns,
cornua) and rear , posterior horns (columns, cornua).
Between the front and rear corners there is the zona
intermedia.
Amid ongoing thin, sometimes obliterated canalis centralis.
White matter, substantia alba is made ​up of nerve fibers
divided into the bundles, anterior, lateral and posterior
funiculi.
In the posterior funiculi can be distinguished medially
fasciculus gracilis and laterally fasciculus cuneatus.
The spinal cord is withdrawing 31 pairs of spinal nerves (C1-8, Th1-12,
L1-5, S1-5, Co), which are formed by combining the front and rear of the
roots. The section of the spinal cord, from which withdraws a pair of
spinal nerves of the spinal segment.
Spinal cord-crosssection
Williams P.L. (ed): Grays Anatomy,
Churchill Livingstone, New York,
1995
F. H. Netter: Anatomický atlas člověka.
Grada/Avicenum, Praha, 2003
Spinal Grey Matter
Functionally discrete neurone groups
microscopic structure
Nuclear columns
Laminae
Laminae VIII.–IX.
contain alfa and
gamma motoneurons,
interneurons and they
are positioned in
ventral horns.
Lateral horns contain
ncl.
intermediolaterales
where preganglion
neurons of the
vegetative neurons
are found.
Bror Rexed 1914-2002
Swedish anatomist
Dorsal horns contain
sc. relay cells,
transmitting signals
from sensitive fibers
coming to spinal cord
from dorsal nerve roots
(lamina I.–VI.).
Laminae
of Rexed
Lamina I – with spinothalamic tract
Lamina II, III – substantia gelatinosa of Rolando
– interneurons, conections with laminae IV.-VI
Lamina IV, V – with spinothalamic,
spinoreticular and spinotectal for sensory cortex
Lamina VI – only in the limb enlargements, with
spinoolivary and spinocerebellar; proprioception
Lamina VII – interneurons, nc. intermed.,
viscerosensitivity
Lamina VIII – imixed interneurons and alpha
neurons, tr. vestibulospinal and reticulospinal
Lamina IX – alpha motoneuron
Lamina X – interneurons, contralateral
communication
Major types of the neurons
Alfa motor (60-100 um; ncc. dorsomedial,
ventromedial, ventrolateral, dorsolateral, central) –
stainable, large, for striated muscles
Gamma motor (40 um) – among alfa motor neurons,
for intrafusal fibres of the muscle spindle
Visceral motor (30-40 um; ncc. intermediolateral,
intermediomedial) – large as gamma motor neurons, for
smooth muscles
Interneurons – small, adjacing
Funicular, relay cells – in dorsal horns
T type cells of the spinal ganglia – spinal cord
cells
Muscle spindles, Golgi bodies
Skin receptors
Sharp pain
temperature, cold
Diffuse pain
A – myelinised fibers
120m/s
C – non-myelinised fibers 1 m/s
Weak stimulation irritates the thick
fibers
Strong stimulation irritates thin
fibers
Anaesthesia switch off thin fibers first;
this is why pain and touch are missing
first
Typ
vláken
A
A
A
C
m
12-20
5-12
2-5
0,3-1,3
m/s
76-120
30-70
12-30
0,5-2,3
Sensitivity to
anestetics
low
low
low
big
Sensitivitz to
hypoxia
middle
middle
middle
small
Function
Proprio,
touch
pressure
pain
warm
pain,
Postgangl.
sympathetic
Giant neurons
– conduct proprioceptive signals
and discriminative signals
Middle-size neurons
- conduct signals of touch and pressure
Small size neurons
- conduct pain signals and temperature signals
Neuron size and
diameter of its
fiber is
proportional to
signal velocity
Classification of receptors following structure
Classification of receptors
Grim, M., Druga, R. et al. Základy anatomie. 4. Nervový systém,
smyslové orgány, kůže. Galén 2012 (v tisku)
Following localization (exteroreceptors, visceroreceptors, proprioreceptors),
Following function (mechanoreceptors, nociceptors, termoreceptors
1. Mechanoreceptors:
a) cutaneous - capsulated, positiond inside basal epidermis and dermis. (VaterPacini bodies, Meissner bodies) or non capsulated bodies (Merkel cells and
receptors of the hair follicles).
Meissner body, quickly adapted for touch (even sweet nock)
Receptors around hair follicle fast adapted, react on movement on skin surface,
bent hair
Vater – Paccini body, quickly are adapted for shake, react on vibration (60 – 300 Hz)
Merkel cell, slowly adapted, reaction on touch and pressure
Ruffini body, slowly adapted, reacts on move
b) Deep mechanoreceptors – are in dermis, in muscle fasciae, in periosteum,
mesentery and in periodontium: Vater-Pacini and Ruffini bodies. React on
pressure, vibration, skin tension, tooth movement.
c) receptors in locomotory apparatus
Muscle spindles, tendon (Golgi) bodies, joint receptors. The are called
proprioreceptors.
2. Nociceptors (pain) are in skin, other tissues, they are free nervous endings
3. Termoreceptors (warm, cold) they are free nervous endings
Skin mechanoreceptors and irritation signals
Types of skin mechanoreceptors
Types of irritation
Meissner body
Quickly adapted
touch, fine nocking
Receptors vlasového folikulu,
Quickly adapted
Movement on skin surface, pillus
is bent
Vater – Paccini body,
Quickly adapted
vibration (60 – 300 Hz)
Merkel cell,
Slowly adapting
Touch , pressure
Ruffini body,
Slowly adapting
Strained skin, overloaded tendon
Quickly adapted receptor - produces signals on beginning and on the end of irritation.
Slowly adapted receptor produces signals through full irritation time (in fact it is a
receptor non adapting).
Grim, M., Druga, R. et al. Základy anatomie. 4. Nervový systém, smyslové orgány, kůže. Galén 2012 (v tisku)
Motoneurons (MN)
Alfa – MN in ventral horn
Medial group (ncl. dorsomedialis a
ventromedialis)
Full spinal cord extend, axial muscles
Lateral group
ncl. centralis, ventrolateralis a
dorsolateralis
Intumescentia, limb muscles
Prox. muscles ventrally and more up in
cord
Ncl. phrenicus – ventromedially C3-5
Ncl. accesorius spinalis – C1-5
Onuf nucleus – S2-3 – sphincters and
perineal muscles
Plate, Ach, extrafusal fibers
Bronislaw OnufOnufrowicz
1863-1928
Spinal White Matter
Organised as funiculi,
which can be
subdivided into
fasciculi containing
tracts
Sensitive
tracts
Tracts…
ascending
ipsilateral or contralateral
spinothalamic
spinocerebellar
Sensitive tracts –
conduct sensitive signals from sensitive receptors
- simple
- surrounded by glial cells with inner capsule
information which iritation occurs: modality,
intensity, localisation, lasting time
mechanoreception – registration where irritation
starts
proprioception – muscle elongation – muscle
spindles, Golgi bodies in tendons
pain
cold and warm
viscerosensitivity - pH, pO2, pCO2, pressure,
traction
Sensitive (ascending) tracts
multineuronal (first neuron is pseudounipolar cell inside spinal ganglion)
ascendent tracts from spinal cord and brainstem to
cerebrum
spinal cord – limbs, body and dorsal head part
(stem tracts – from CN nerves – from face)
a part of fibers is directed to CRBL (indirect
sensitive pathways) – we are not perceive these
signals
two main systems are noted
anterolateral
lemniscal
Anterolateral system
Spinothalamic – pain
Spinoreticular – sensitivity in the
activation system
Spinotectal – movement head and neck
Spinobulbothalamic – tactile
sensations
Spinoolivary – proprioception for
cerebellum
Spinocerebellar – proprioception from
muscles, joints and tendons
Anterolateral system
spino-thalamic tract
1.N – pseudounipolar cell od spinal ganglion
2.N – Rexed zone I, IV, V, to contralateral ventral and
lateral funiculi (to thalamus)
3.N – from thalamus to cortex
pain, sharp + intensive
spino-reticular tract
1.N - dtto
2.N - Rexed zone V,VII, to contralateral ventral and
lateral funiculi (to medial ncc. of RF)
3.N - RF – thalamus (fibers to hypothalamus)
4.N. thalamus - cortex
low, dull, unlocalised pain (developmentally older)
Spinocerebellar
anterior tract
Spinocerebellar
posterior tract
Lemniscal system
– dorsal funicular system
tr. spino - bulbo - thalamo - corticalis
Kahler rule
1.N – pseudounipolar cell in spinal ganglion, dorsal
fasciculi, collaterals
2.N - nc. gracilis, nc. cuneatus medialis
through lemniscus medialis (decussatio) to thalamus
(ncl. ventralis posterolateralis, VPL), also to CRBL
3.N - tr. thalamo- corticalis (S1, area 3,1,2,)
sensitive areae – columnar arrangement, specific for
receptors
laminar arrangement of projecting cells
somatotopic arrangement
touch, discrimination, limb position
Fasciculus cuneatus
and gracillis
Williams P.L. (ed): Grays Anatomy, Churchill
Livingstone, New York, 1995
Spinal cord lesion
Brown Séquard syndrome
On the lesion side – spastic palsy;
loose of deep and discriminative
feelings (non-crossed spinobulbar
tract)
On the contralateral side - loose of
the pain and thermic feelings
(crossed spinothalamic tract)
Motor
tracts
Descending tracts
Corticospinal –– voluntary movements
Tectospinal – visual perception
Reticulospinal – gamma loop mechanism
Vestibulospinal – antigravitation muscles
Medial longitudinal fasciculus –
coordination of the head movement based on the
eye and vestibular informations
White Matter –Tracts …
descending
MB
Pons
MO
SC
SC
Motor (descending)
tracts
are responsible for
voluntary and
involuntary motor
activities
a) due to
informations coming
from sensitive and
sensory systems,
b) due to tuning
impulses from limbic
system.
Background of
involuntary
activity is
reflexoric activity
corticospinal fibers ingrowths to
medulla in following order
fibers from M1 to lamina VII-IX, from S
to dorsal horns . part on motoenurons
(IX), part on interneurons (VII)
crossed part of pyramidal tract – distal
muscles
Noncrossed part of pyramidal tract
postural muscles
corticonuclear
corticospinal
Motor tract inside stem
r. rubro - spinalis
tr. tecto - spinalis
tr. reticulo - spinalis
tr. vestibulo - spinalis
tr. intersticio - spinalis
Stem motor tracts
Tr. NR – spinalis
NR, decussatio tegmenti ventralis, later. funiculi,
more in the spinal cord V-VII
exciting influence on proximal limb muscles and
flexor motoneurons. It transmits cortical and
cerebellar impulses
Tr. tecto – spinalis
inside deep layers of colliculus superior, dec. teg.
dorsalis, it ends in upper cervical segments IV-VII
of spinal cord; it controls motor activities of a head
and neck due to auditory and visual impulses.
Functional systems of motor tracts
M+L+3.
lateral system
medial system
Controls fine,
fractioned and
isolated
movements of
upper limb
muscles
Controls erectile position,
tone of nuchal and back
muscles;
Controls coordination of
the limb muscles
Functional systems of motor tracts
M+L+3.
Medial system –
crossed and noncrossed, all stem tracts
instead of tr. NR-Spinal
a tr. Co-Spinal anterior
It begins from M 1, M2, FEF
It activates spinal cord motoneurons in medial
parts of ventral horns.
It controls motor activity of a big muscle groups,
antigravitation muscles.
Functional systems of motor tracts
M+L+3.
Lateral system
- crossed, it formed by crossed part of
tr.Co-Spinal lateral, NR-Spinal M1,
It activates motoneurons of lateral one half of ventral
spinal horns.
It controls fine motor movements (groups of small
muscles).
Functional systems of motor tracts
M+L+3.
3. system
crossed and non crossed, it is composed of
tr. RF-spinal (tr. raphe – spinal and coeruleospinal),
and is projecting to ventral spinal cord horns and
to basis of dorsal horn.
Fibers from RF-spinal are noradrenergic and
serotoninergic.
It controls limbic system on motor movenments
(involuntary emotional motor skills).
Brown-Séquard syndrome:
interruption of corticospinalis lat.
tract:
ipsilateral spastic palsy
below lesion
Babinski on the side of
lesion
interrrupted dorsal funiculi:
ipsilateral loose of tactile
feeling; vibrations and
proprioception below
lesion are normal
interruption of the spinothalamic
tract:
contralateral loose of pain
and temperature feeling,
usually 2-3 segments
below lesion.
* = lesion side
1 = atonic palsy
2 = spastic palsy and loose of
mechanoreception and
proprioreception
3 = loose of temperature and pain
Full spinal cord lesion
Immediately after irritation
Palsy of muscles below level of irritation
Loose of feelings from the same area
Loose of tendon and skin reflexes
Urine retention
Low peristalsis
Dry skin
After some time –
Muscle tonus increases
Tendon and skin reflexes increase
Spontaneous micturition
iflesion is at level of cervical intumescentia – spastic quadruplegia
If lesion is at level of lumbar intumescentia – spastic paraplegia
If lesion is at level C4 – diaphragma palsy