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NERVOUS SYSTEMNERVOUS SYSTEM
It is the master It is the master controlling and controlling and communicating communicating system of the bodysystem of the body..
StructurallyStructurally, it has , it has two subdivisionstwo subdivisions: :
((11 ) )Central nervous Central nervous systemsystem..
((22 ) )Peripheral Peripheral nervous systemnervous system..
NERVOUS SYSTEMNERVOUS SYSTEM
FunctionallyFunctionally, it is divided into, it is divided into: : Somatic N.SSomatic N.S. : It controls voluntary . : It controls voluntary
activitiesactivities..Autonomic N.S.Autonomic N.S. :It controls :It controls
involuntary activitiesinvoluntary activities..
CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM
It is composed of It is composed of the the brainbrain and and spinal cordspinal cord..
They occupy the They occupy the dorsal body cavitydorsal body cavity..
They act as the They act as the integrating and integrating and command centers command centers of the nervous of the nervous systemsystem . .
CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM
Its interior is Its interior is organized into organized into GrayGray and and White White mattermatter . .
CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEMGray matterGray matter::
Consists of Consists of nerve cells nerve cells ((neuronsneurons) ) embedded in embedded in neuroglianeuroglia..
Each neuron has two Each neuron has two types of nerve types of nerve processesprocesses::
DendritesDendrites : short : short processes of the cell processes of the cell bodybody..
AxonAxon : : longest process longest process of the cell bodyof the cell body . .
CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM
White matterWhite matter::Consists of Consists of nervenerve
fibersfibers embedded embedded in in neuroglianeuroglia..
PERIPHERAL NERVOUS PERIPHERAL NERVOUS SYSTEMSYSTEM
It is the part of the It is the part of the nervous system nervous system outside the CNSoutside the CNS..
It consists of It consists of (12) pair(12) pair cranialcranial and and (31) pair (31) pair ofof spinalspinal nerves nerves . .
These nerves act as These nerves act as communication lines communication lines between all parts of between all parts of the body and the CNSthe body and the CNS..
PERIPHERAL NERVOUS PERIPHERAL NERVOUS SYSTEMSYSTEM
The nerves are The nerves are formed of grayish formed of grayish white cordswhite cords..
Each cord is Each cord is formed of nerve formed of nerve fibers (axons) fibers (axons) supported by supported by delicate areolar delicate areolar tissuetissue . .
CRANIAL NERVESCRANIAL NERVES
The twelve pair of The twelve pair of nerves supply nerves supply structures in the structures in the head and neckhead and neck..
The The 1010thth (vagus)(vagus) supplies structures supplies structures in the thorax and in the thorax and abdomenabdomen..
SPINAL NERVESSPINAL NERVES
They are named They are named according to the region of according to the region of the spinal cord to which the spinal cord to which they are associatedthey are associated..
They are: They are: 8)8)cervical.cervical. 12)12)thoracic.thoracic. 5)5)lumbarlumbar..
55))sacralsacral andand ((11)) coccygealcoccygeal..
LENGTH OF SPINAL NERVESLENGTH OF SPINAL NERVES
In the upper In the upper cervical region, cervical region, they are short and they are short and horizontalhorizontal..
The lumbar and The lumbar and sacral nerves sacral nerves below the level of below the level of termination, form a termination, form a vertical bundle vertical bundle (Cauda Equina)(Cauda Equina)..
LEVEL OF TERMINATION OF LEVEL OF TERMINATION OF S.CS.C..
AdultsAdults: : It terminates inferiorly at It terminates inferiorly at
the lower border of the the lower border of the 1st lumbar1st lumbar vertebra vertebra..
ChildrenChildren :: It is relatively longer and It is relatively longer and
ends at the upper border ends at the upper border of the of the third lumbarthird lumbar vertebravertebra..
SPINAL NERVESSPINAL NERVES
Each spinal nerve Each spinal nerve is attached to the is attached to the spinal cord by two spinal cord by two roots : roots : Anterior Anterior and and PosteriorPosterior..
ANTERIOR ROOTANTERIOR ROOTIt carries nerve impulses It carries nerve impulses
awayaway from the central from the central nervous system nervous system (Efferent)(Efferent) fibers fibers..
The efferent fibers to the The efferent fibers to the skeletal muscles are skeletal muscles are called called (Motor)(Motor) fibers fibers..
They arise from the They arise from the anterior gray horn cells anterior gray horn cells of the spinal cordof the spinal cord
POSTERIOR ROOTPOSTERIOR ROOT
It carries impulses It carries impulses toto the the central nervous system central nervous system (Afferent)(Afferent) fibers fibers..
It conveys sensations of It conveys sensations of pain, touch and pain, touch and temperature temperature (Sensory)(Sensory) fibersfibers..
Their cell bodies are Their cell bodies are located in the posterior located in the posterior root ganglionroot ganglion..
SPINAL NERVESPINAL NERVE
At the intervertebral At the intervertebral foramen the anterior foramen the anterior and posterior roots and posterior roots unite to form a spinal unite to form a spinal nervenerve..
Each spinal nerve is a Each spinal nerve is a mixture of motor and mixture of motor and sensory fiberssensory fibers..
FORMATION OF THE RAMIFORMATION OF THE RAMI
On emerging from On emerging from the foramen, each the foramen, each spinal nerve spinal nerve divides into a large divides into a large ventralventral (anterior) (anterior) ramus and a ramus and a smaller smaller dorsal dorsal (posterior) ramus(posterior) ramus..
DISTRIBUTION OF THE RAMIDISTRIBUTION OF THE RAMI
The The posterior ramiposterior rami pass posteriorly to pass posteriorly to supply the skin and supply the skin and muscles of the backmuscles of the back..
The The anterior ramianterior rami supply the skin and supply the skin and muscles of the limbs muscles of the limbs and the anterolateral and the anterolateral wall of the bodywall of the body..
PLEXUSESPLEXUSES
At the root of the At the root of the upper limb, the upper limb, the anterior ramianterior rami unite to form the unite to form the CervicalCervical and and BrachialBrachial plexuses plexuses..
At the root of the At the root of the lower limb, they lower limb, they form the form the Lumbar Lumbar and and Sacral Sacral plexusesplexuses..
AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM
It is concerned with It is concerned with the innervation of the the innervation of the involuntary structures involuntary structures (heart, smooth (heart, smooth muscles ,glands)muscles ,glands)..
It is divided intoIt is divided into: :
AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM
11 . .SympatheticSympathetic system:system: it prepares the body for it prepares the body for an emergencyan emergency..
22 . .Parasympathetic Parasympathetic systemsystem: :
It conserves and restores It conserves and restores energyenergy..
Each system hasEach system has: : Efferent, Afferent fibers Efferent, Afferent fibers
and ganglia to relayand ganglia to relay . .
SYMPATHETIC SYSTEMSYMPATHETIC SYSTEM
Efferent fibersEfferent fibers: : Their cell bodies Their cell bodies
are located in the are located in the lateral columnlateral column of of the spinal cord the spinal cord from the level of from the level of (T1- L2)(T1- L2)..
They are divided They are divided intointo: :
SYMPATHETIC SYSTEMSYMPATHETIC SYSTEM
A. preganglionic fibersA. preganglionic fibersThey leave the lateral column They leave the lateral column
of the spinal cord in the of the spinal cord in the anterior nerve rootsanterior nerve roots..
They pass in the They pass in the White ramiWhite rami communicantescommunicantes to the to the paravertebral gangliaparavertebral ganglia of of the sympathetic trunkthe sympathetic trunk..
SYMPATHETIC TRUNKSSYMPATHETIC TRUNKSThey are two ganglionated They are two ganglionated
trunks that extend close to the trunks that extend close to the vertebral columnvertebral column..
Each trunk is formed of (3) Each trunk is formed of (3) ganglia in the neck, (12) in the ganglia in the neck, (12) in the thorax, (5) in the lumbar and (5) thorax, (5) in the lumbar and (5) in the sacralin the sacral..
The two trunks end inferiorly by The two trunks end inferiorly by forming one ganglionforming one ganglion . .
GanglionGanglion : collection of nerve : collection of nerve cells (neurons) cells (neurons) outsideoutside the the central nervous systemcentral nervous system..
PREGANGLIONIC FIBERSPREGANGLIONIC FIBERS
11.. They relay at the They relay at the correspondingcorresponding ganglia ganglia by synapsing with an by synapsing with an excitor cell of the excitor cell of the ganglionganglion . .
22.. Fibers in the Fibers in the upperupper thoraxthorax may may travel uptravel up in in the sympathetic trunk to the sympathetic trunk to relay in the relay in the cervical cervical gangliaganglia..
PREGANGLIONIC FIBERSPREGANGLIONIC FIBERS33 . .Splanchnic nervesSplanchnic nervesThey pass through the They pass through the
thoracic sympathetic thoracic sympathetic ganglia ganglia withoutwithout relayrelay..
They pass through the They pass through the diaphragmdiaphragm..
They areThey are: : a. Greater Splanchnica. Greater Splanchnic
nerve nerve (5(5thth -9 -9thth ) ) thoracic thoracic gangliaganglia..
It relays in the celiac It relays in the celiac gangliaganglia . .
PREGANGLIONIC FIBERSPREGANGLIONIC FIBERS
b. Lesser splanchnicb. Lesser splanchnic nerve nerve (10(10thth & 11 & 11thth ) ) ganglia :it synapses with ganglia :it synapses with ganglia in the lower part ganglia in the lower part of the celiac trunkof the celiac trunk..
C. Least splanchnicC. Least splanchnic nerve nerve (12(12thth)) ganglion ganglion: :
It relays in ganglia of the It relays in ganglia of the renal plexusrenal plexus..
POSTGANGLIONIC FIBERSPOSTGANGLIONIC FIBERS
They pass through They pass through the the Gray rami Gray rami communicantescommunicantes to join the spinal to join the spinal nerves to supply nerves to supply the smooth the smooth muscles in the muscles in the blood vessels, blood vessels, sweat glands and sweat glands and erector pili muscles erector pili muscles of the skinof the skin..
POSTGANGLIONIC FIBERSPOSTGANGLIONIC FIBERS
The postganglionic The postganglionic fibers of the fibers of the splanchnic nerves splanchnic nerves supply the smooth supply the smooth muscle and glands muscle and glands of the visceraof the viscera..
AFFERENT FIBERSAFFERENT FIBERSThey arise from the wall of They arise from the wall of
the viscerathe viscera..They pass through the They pass through the
sympathetic ganglia sympathetic ganglia without without relayrelay..
They enter the spinal nerve They enter the spinal nerve through the through the white ramiwhite rami..
They relay in the posterior They relay in the posterior root ganglion of the root ganglion of the corresponding spinal nervecorresponding spinal nerve..
Their central axons pass to Their central axons pass to the spinal cordthe spinal cord..
PARASYMPATHETIC PARASYMPATHETIC SYSTEMSYSTEM
Efferent fibersEfferent fibers (Preganglionic)(Preganglionic): :
((11 ) )Cranial partCranial part: : Their cells are Their cells are
located in the located in the brainbrain..
They form part ofThey form part of the the cranial cranial nerves (111, nerves (111, V11,1X &XV11,1X &X))..
PARASYMPATHETIC GANGLIAPARASYMPATHETIC GANGLIA
They relay into ganglia They relay into ganglia situated situated closeclose to the to the tructures they supplytructures they supply . .
In the head & neck, In the head & neck, they are the (ciliary, they are the (ciliary, otic, pterygopalatine otic, pterygopalatine and submandibular) and submandibular) gangliaganglia..
PARASYMPATHETIC PARASYMPATHETIC SYSTEMSYSTEM
((22 ) )Sacral partSacral part: : The fibers arise from The fibers arise from
the the gray matter of gray matter of the 2the 2ndnd,3,3rdrd and 4 and 4thth sacral spinal sacral spinal segmentssegments..
They form the They form the Pelvic Pelvic splanchnic nervessplanchnic nerves..
They relay in ganglia They relay in ganglia in the walls of the in the walls of the viscera or in the viscera or in the hypogastric plexuseshypogastric plexuses..
PARASYMPATHETIC PARASYMPATHETIC SYSTEMSYSTEM
Afferent fibersAfferent fibers: : They pass from the They pass from the
viscera to the viscera to the sensory ganglia of sensory ganglia of the cranial nervesthe cranial nerves or the posterior root or the posterior root ganglia of the ganglia of the sacrospinalsacrospinal nerves nerves..
The central axons The central axons pass to the central pass to the central nervous systemnervous system..
