Spinal cord

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

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http://www.brain.rike n.go.jp/english/b_rear/ b4_lob/images/k_mik oshiba_l1.gif

Spinal cord-segment

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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