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8/18/2019 CNS_Fk_unjani_2

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Anatomy of formatio reticularis

RF consists of widely spaced neurons loosely arranged

into nuclear groups throughout entirely BS tegmentum.

Fills the space not occupied by CN nuclei,

supplementary sensory and motor nuclei, named longand short tract.

Caudal limit : medullo-cerical !unction

Rostral limit : midbrain-diencephalic !unction

"uge dendritic tree -# reticular appearance

"eterogenous connections of any single part of the CNS,

influence all mental, motor, and sensory functions


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Classification of RF nuclei

$. Raphe nuclei % &'tent the entire length of the median plane of BS

(. )edial *central+ gigantocellular nuclei %

&'tent through the pontomedullary tegmentum, lateral to Raphenuclei

% hey contain the conspicuous gigantocellular neuron *magnocellular

group+

. ateral paricellular *small celled+ nuclei % &'tent from medullo-cerical !unction to midbrain

/. Cerebellar RF nuclei

% )ainly connect with Cerebellum


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Afferent of RF0

Spinal cord % ract spinoreticularis

% ract spinothalamicus

0 BS

% Collaterals from sensory nuclei of the CN *CN 1,1222,Nuc. Solitarius+

% ract tectoreticularis

% ract reticulo-reticularis

0 Cerbellum

0 Forebrain

% imbic system

% Basal ganglia

% Cerebral corte'


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Efferent of RF

0 RF efferents reach all parts of CNS, from

Spinal cord through Cerebral corte'

0 Spesific efferent : % ract reticulospinal

% ract reticulobulbar


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Ascending Reticular Activating System (ARAS)

$. Rostral half of RF pro!ects to forebrain by an 3R3S

(. 4estruction of the rostral pontine tegmentum

Causes transitory loss of consciousness

. 4estruction of the midbrain RF

5ermamnently abolish consciousness

Caudal halh of RF maintains breathing, blood pressure, others refle'

Conscious wa6ing state re7uires neuronal pools 8

interconnection : Rostral RF, halamus, Cerebral corte'


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Function of formatio reticularis

Mental state : consciousness, attention span, alerting responses, sleep-wake cycle. RF is active during sleep and wake.

Homeostasis and neurovegetative reflexes

RF mediates reflexes that control the activity of viscera and glands

in the interest of homeostasis. In concert with forebrain, RF centers control breathing, pulse,

blood pressure, gastrointestinal, genitourinary, electrolyte balance,pupillary sie, ocular movement

!ract.reticulospinal controls blood pressure

"ediates reflex : coughing, sneeing, swallowing, vomiting,hiccuping, gagging, chewing, sucking, feeding

Somatomotor # sensorimotor reflex

$ostural reflex, extensor%flexor muscle tone, vestibular reflex


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Cranial nere nuclei

Supplementary motor

nuclei :

)9 : 2nferior

oliary nuclei5ons : Nuclei of

pontine

)id : Red

nucleus ,

Substantia nigra

Neuronalarrangement

5athways

ong sensory

tracts

5rofuse short 8

long, asc 8 descF)

Cerebellar eff 8

aff


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Cross section of tegmentum

Cranial nerve nuclei

Supplementary motor nuclei : MO : Inferior olivary nuclei

Pons : Nuclei of pontine

Mid : Red nucleus , Substantia nigra

Neuronal arrangement Pathays

!ong sensory tracts

Profuse short " long, asc " desc

#!M

Cerebellar e$ " a$

Central tegmental tract

%ypothalamic


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Cross section of medulla oblongata


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Composition of Basis BS

&asis transmits deacending cortical e$erent, consistof

Cortico'pontine (ractus

Pyramidals tracts

Cortico'bulbar (rac

Cortico'spinal (ract

)i$erence in the basis of Mid, Pons, MO

Mid : conveys cortico'bulbar *spinal *pontinetracts

Pons : largest basis, Nuclei pontine

MO : smallest


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0 Cerebellum0 riad

0 hree pedunculi

0 hree layers of corte' cerebellum

0 hree lobus

0 hree phylogenetic

0 hree hemisphere0 hree nuclei

0 hree fibers


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0 cerebellum

0 Situated :

0 behind the pons varolii0 immediatelly belo the the posterior

portion of the cerebrum

0 occupying the posterior cranial fossa


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0 Function of cerebellum

0 coordination of :

0 voluntary muscular movement0 posture

0 balance !e"uilibrium


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#he overall structure of the

cerebellum is similar to that

of the cerebrum

in the sense that

superficial cellularlayers form a corte$% hich

covers several

deep nuclei embedded in

the hite substance.


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4amage to the cerebellum

causes disturbances of motor

function without oluntary

paralysis.

he cerebellum consists ofhree lobes

hree layers of the corte'

hree nuclei gie the

output fibers

hree pairs of cerebellar

peduncles


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2nferior cerebellar peduncle

Chiefly input fibers

Consists of restiform body and !u'ta-

restiform body

)iddle cerebellar peduncle Brachium

pontisargest

&ntirely input

Connect basis pontis to the

cerebellum

Superior cerebellar peduncle Brachium

con!unctium

Connects )idbrain to the

cerebellum

)ostly output fibers


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Receies information from many

sources, s6in, !oints, muscles,estibular and auditory apparatus and

the eye.

he output send to the motor cortical

area and the RF of the brain stem

he output send to the motor cortical

area and the RF of the brain stem


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Cortical layer )olecular layer

2nterneuron : Bas6et

and stellate

neuron

ayer of 5ur6in!e cells

3 single row of

bodies of

5ur6in!e cells

5rincipal cells

;ranular layer

;ranule cells,

;olgi cells.


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he fie ma!or cell

types of the

cerebellar corte' :

;ranular cells

;olgi cells

5ur6in!e cells

Bas6et cells

Stellate cells

he cells are

arranged in a

trilaminar pattern


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3fferent fibers

&fferent fibers


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5osterior lobe of cerebellum circuitry


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Flocconodular circuity


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3nterior lobe cerebellum circuitry


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5osterior lobe cerebellum syndrome

+eo-cerebellar lobe syndrome, resulting fromaccidents, trauma, tumor, degenerationdiseases, is manifested by :' taxia loss of coordination of voluntary

movements ' *ecreased muscle tone' Rate, range, and force of movements are abnormal

intention tremor

' *ysmetria' *ysdiadochokinesia as repetitive hand pronation '

supination


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Spinal cord $

0 9ccupies the upper two-thirds of the ertebral

canal

0 Conductor of impulses between the brain and

the peripheral neres0 3scending pathways carry impulses to the brain

from all parts of the body e'cept the head

0 4escending pathways0 Contains a wealth of intrinsic neuronal circuits

subsering a multitude of spinal refle'es


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Spinal cord (

0 3lmost => cm long cylindrical part of CNS0 4iameter : $ % $.= cm0 $ pairs of spinal nere, distribute sensory and

motor fibers to all parts of the body.0 &nlargement : cerical 8 lumbal-sacral

enlargement0 Cross section :

0 ;ray and ?hite substance.0 Fissura0 Central canal


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Spinal cord

0 Functions

0 Breathing

0 4igestion and elimination0 Blood pressure and pulse

0 Sweating and other glands secretions

0 5iloerection0 5enile clitoral erection


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0 Spinal cord segment $ at leel spinous

process of the ertebrae C@

spinal cord segment $ at leel spinous process

of the ertebrae$>spinal cord segment S$ at leel spinous process

of ertebrae $(

termination of conus medullaris discus

intereteb.,$-(ermination of sbarachnoid space at S( or S

termination of filum terminale on the coccy'.


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0 Spinal cord :Spinal cord :

e'tends from the leel of the foramen magnum to thee'tends from the leel of the foramen magnum to the

body of the $st or (body of the $st or (ndnd lumbal ertebra and length of /lumbal ertebra and length of /

cm.cm.

2ts has fie leels * cerical, thoracic, lumbar, sacral and2ts has fie leels * cerical, thoracic, lumbar, sacral andcoccygeal + with a total of $ to ( pairs of spinal neres.coccygeal + with a total of $ to ( pairs of spinal neres.

ransersal section :ransersal section :

Agray matter : is " shape : dorsal horns, entral horns,Agray matter : is " shape : dorsal horns, entral horns,

lateral horns. 2n central : central canal.lateral horns. 2n central : central canal.Awhite matter.: has collumna funiculi : dorsal, lateralAwhite matter.: has collumna funiculi : dorsal, lateral

and dorsal.and dorsal.


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?hite matter

0 Column

0 3nterior funiculus

0 ateral funiculus

0 5osterior funiculus

0 he fibers in the column consist of

0 4escendens racts

0 3scendens racts


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;ray matter

0 "shape, with central canal

0 3nterior horn *motoric neuron +

0ateral horn * 5reganglionic Neuron+

0 5osterior horn *sensoric neuron +

0 Re'eds aminae * 2,22 % D +


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0 4escending pathways of the spinal white matter 3. corticospinal tractB. corticobulbair tract.C. coticopontine tract


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3scenden sensory pathway

0 4iided into three groups

0 5athways for pain 8 temperature

05athways for tactile information, ibration,position sense * static posistion sense and

6inesthesia +

0 5athways for somatosensory impulse to

the cerebellum * Spino-cerebellar tract,

cuneo cerebellar tract +


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4escending pathways

0 Cortico-spinal tract A

0 1estibulo-spinal tract

0ecto-spinal tract

0 Rubro-spinal tract

0 Reticulo-spinal tract

0 )edial longitudinal fasciculus * mi'ed +


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0 )eningen :)eningen :

dura mater dura mater , epidural , subdural, epidural , subdural

arachnoidea mater !membranarachnoidea mater !membran and subarachnoidand subarachnoid

spaces spatiumspaces spatium

pia mater pia mater dural compartment of the s6ull :dural compartment of the s6ull :

$. the cerebral fal',$. the cerebral fal',

(. cerebellar tentorium %(. cerebellar tentorium %supratentorial spacesupratentorial space containscontains

cerebrumcerebrum ,, infratentorial spaceinfratentorial space oror posterior fossaposterior fossa containscontains brainstem and cerebellum&brainstem and cerebellum&

'& #he cerebellar fal$&separated cerebelli hemisphere'& #he cerebellar fal$&separated cerebelli hemisphere

left and rightleft and right


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)eningen


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5rotectie structure ertebral column, meningen,

epidural adipose csf


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Cerebrospinal


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Cerebrospinal

fluids


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ascular supply of the CS

2nternal carotid system 3nterior cerebral artery

)iddle cerebral artery

3nterior communicating artery

1ertebrobasilar system eft 8 right ertebral artery merge on the anterior aspect of

the caudal pons to from the basilar artery.

Branches :

3nterior inferior cerebellar arteries 5ontine arteries

Superior cerebellar arteries


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o the cerebral hemispheres 2nternal carotid system

3nterior cerebral artery )iddle cerebral artery

1ertebrobasilar system 5osterior cerebral arteries o the deep of the brain

2nternal carotid artery 3nterior cerebral arteries )iddle cerebral arteries

Basilar artery 5osterior cerebral arteries

5osterior communicating arteries halamic arteries


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o the Cerebellum1ertebrobasilar system

5osterior inferior cerebellar arteries

3nterior inferior cerebellar arteries Superiorr cerebellar arteries

o the Brain stem1ertebral arteries

Bulbar arteries 3nterior spinal arteries5osterior inferior cerebellar arteries


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o the pons

3nterior inferior cerebellar arteries

5ontine arteries

Superiorr cerebellar arteries

o the midbrain

Superior cerebellar arteries5osterior cerebral arteries

5osterior communicating arteries


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hrough carotid canal

)a!or branches :

0 9pthalmic branch

0 3nterior communicating branch0 3nterior cerebral artery

0 )iddle cerebral artery


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hrough foramen magnum Branches of ertebral artery :

0 3nterior spinal0 5osterior inferior cereballar arteries0 5osterior spinal

Branches of basilar artery0 3nterior inferior cerebellar arteries0 abyrinthine0 5ontine arteries0 Superior cerebellar arteries0 5osterior cerebellar arteries *terminal branch+

0 5osterior communicating branches


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he serebral arterial circle is an important anastomosis atthe base of the brain between the four arteries

* ertebrals and internal carotids +0 Structure :

% 3nterior cerebral arteries % 3nterior communicating arteries

% 5osterior communicating arteries

% 5osterior cerebral arteries

% 2nternal carotid arteries

0 Function Connection between carotid and ertebral arteries


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Blood

supply of

spinal cordand BS


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0 he large channels draining the superficial

and deep cerebral eins are form within

the dura mater

0 he dural sinuses drain into internal

!ugular ein or into emissary eins


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0 Structures :

% ;reat eins of galen % Straight sinus eft 8 right transerse sinus % Sigmoid sinus 2nferior sagittal sinus

% Superior sagittal sinus % Confluens % 9ccipital sinus

0

% Superior petrosal sinus % 2nferior petrosal sinus % Caernosus sinus % 2ntercaernosus sinus


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0 references

$. Stephen ; ?a'man Clinical

Neuroanatomy )c ;raw "ill (>>

( Richard S Schnell Clinical Neuroanatomy

5; 3sian &dition $E/

&rnest ? 3pril Neuroanatomy Gohn?illey 8 Sons $EH@


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