NERVOUS NERVOUS SYSTEMSYSTEM

Chona Araga, M.D.Chona Araga, M.D.

- Nervous System is a group of tissues - Nervous System is a group of tissues composed of highly specialized cells composed of highly specialized cells possessing the characteristics of possessing the characteristics of excitability and conductivity excitability and conductivity

MORPHOLOGICAL DIVISIONS:MORPHOLOGICAL DIVISIONS:

A. CENTRAL NERVOUS SYSTEMA. CENTRAL NERVOUS SYSTEM

1. Brain1. Brain

2. Spinal cord2. Spinal cord

B. PERIPHERAL NERVOUS SYSTEMB. PERIPHERAL NERVOUS SYSTEM

1. Cranial Nerves (12 pairs)1. Cranial Nerves (12 pairs)

2. Spinal Nerves ( 31 pairs)2. Spinal Nerves ( 31 pairs)

3. Autonomic Nervous System 3. Autonomic Nervous System

FUNCTIONAL DIVISIONS:FUNCTIONAL DIVISIONS:

A. SOMATIC EFFERENTA. SOMATIC EFFERENT- innervating somatic structures like - innervating somatic structures like skeletal muscles and skin.skeletal muscles and skin.

B. VISCERAL EFFERENTB. VISCERAL EFFERENT- innervating visceral or involuntary - innervating visceral or involuntary structures like smooth muscles, cardiac structures like smooth muscles, cardiac muscles and glands. This is the muscles and glands. This is the autonomic nervous systemautonomic nervous system

TYPES OF CELLS IN THE TYPES OF CELLS IN THE NERVOUS SYSTEMNERVOUS SYSTEM

- The nervous system is composed of a - The nervous system is composed of a special tissue containing two major special tissue containing two major types of cells:types of cells:

1. Neurons1. Neurons

- the active conducting elements- the active conducting elements

2. Neuroglia2. Neuroglia

- the supporting elements- the supporting elements

NEURON

- basic unit of the nervous system which conducts electrical impulses from one part of the body to another

-consists of a cell body (perikaryon), containing a single nucleus, and processes transmitting impulses to and from the body

TWO TYPES OF PROCESSES

A. DENDRITES – group of short, unsheathed processes arranged like branches of a tree that transmit impulses toward the cell body

B. AXONS – a single, elongated sheathed process conducting impulses away from the cell body.

ACCESSORY CELLS – the non nervous elements consist of blood vessels, connective tissue, and supporting cells known collectively as neuroglia

SYNAPSE

- point of connection between neurons.The axon of one neuron makes functional contact with

dendrites of another neuron. Main neurotransmitters:1. epinephrine (adrenalin)2. norepinephrine (nor adrenaline)3. acetylcholine

NERVE IMPULSEA. MYELIN SHEATH – insulating material covering axons in central and peripheral nervous system- the thicher the myelin sheath is, the faster the passage of nerve impulse will be.- the electril impulse jumps from node to node in myelin sheath instead of traveling continuously along the nerve fiber. (SALTATORY CONDUCTION OF IMPULSES)

CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM- - Central nervous system includes the brain and spinal Central nervous system includes the brain and spinal

cord.cord.- It is divided grossly into gray and white matter:It is divided grossly into gray and white matter:

A. Gray matterA. Gray matter- so called because of its appearance and - so called because of its appearance and

preponderance of preponderance of nerve cell bodies and true nerve cell bodies and true dendrites.dendrites.

B. White matterB. White matter- composed chiefly of myelinated nerve fibers- composed chiefly of myelinated nerve fibers- white in gross appearance - and few, if any, - white in gross appearance - and few, if any,

nerve cell nerve cell bodies.bodies.- In the spinal cord an H-shaped central region of - In the spinal cord an H-shaped central region of

gray gray matter is surrounded by white mattermatter is surrounded by white matter

BRAINBRAIN

- part of the central nervous system - part of the central nervous system contained within the skull.contained within the skull.

- most complex and largest mass of - most complex and largest mass of nervous tissue in the body and contains nervous tissue in the body and contains literally billions of nerve cells.literally billions of nerve cells.

- The average weight of the human brain - The average weight of the human brain in the adult is approximately 1380gms in in the adult is approximately 1380gms in the male and 1250 grams in the females.the male and 1250 grams in the females.

EMBRYOLOGICAL DIVISIONS OF EMBRYOLOGICAL DIVISIONS OF THE BRAINTHE BRAIN

1. Forebrain (Prosencephalon)1. Forebrain (Prosencephalon)a. Telencephalon (cerebrum)a. Telencephalon (cerebrum)b. Diencephalon ( thalamus, hypothalamus, b. Diencephalon ( thalamus, hypothalamus,

epithalamus, epithalamus, subthalamus)subthalamus)2. Midbrain (Mesencephalon)2. Midbrain (Mesencephalon)

a. Corpora quadrigemina (tectum) - 2 superior a. Corpora quadrigemina (tectum) - 2 superior colliculicolliculi

2 inferior colliculi2 inferior colliculib. Cerebral pedunclesb. Cerebral pedunclesc. Cerebral Aqueduct of Sylvius (iter)c. Cerebral Aqueduct of Sylvius (iter)

3. Hindbrain (Rhombencephalon)3. Hindbrain (Rhombencephalon)a. metencephalon (cerebellum, pons)a. metencephalon (cerebellum, pons)b. myelencephalon (medulla oblongata)b. myelencephalon (medulla oblongata)

1. PROSENCEPHALON1. PROSENCEPHALON

AA. TELENCEPHALON. TELENCEPHALON (CEREBRUM) (CEREBRUM)

- represents seven-eights of weight of - represents seven-eights of weight of brainbrain

- responsible for discriminatory - responsible for discriminatory identification identification of and integration of sensory of and integration of sensory information, information, memory reasoning, memory reasoning,

- for use of language- for use of language- for emotional behavior - for emotional behavior - for initiation of movement- for initiation of movement

FISSURES OF CEREBRUMFISSURES OF CEREBRUM1. Longitudinal Fissure1. Longitudinal Fissure

- runs from the posterior to the - runs from the posterior to the anterior anterior aspects almost completely aspects almost completely dividing it dividing it

into 2 hemispheres.into 2 hemispheres.

- each hemisphere has a full set of - each hemisphere has a full set of

centers for sensory and motor centers for sensory and motor

activities of the body, and each activities of the body, and each

associated with one side of the body.associated with one side of the body.

- the hemispheres are connected in - the hemispheres are connected in the midline the midline by the by the corpus callosumcorpus callosum

2. Lateral Sylvian fissure2. Lateral Sylvian fissure

- between the - between the frontal and frontal and parietal lobes parietal lobes above and above and temporal lobe temporal lobe below.below.

- associated with - associated with centers for speech centers for speech and hearing.and hearing.

3. Central Sulcus (Rolandic 3. Central Sulcus (Rolandic Fissure)Fissure)

- between frontal - between frontal and parietal lobes- and parietal lobes- associated with associated with centers for both centers for both motor and sensory motor and sensory functions.functions.

4. Transverse fissure4. Transverse fissure- between the - between the cerebellum and the cerebellum and the cerebrumcerebrum

5. Parieto - occipital 5. Parieto - occipital fissurefissure

- between the occipital - between the occipital and parietal lobes.and parietal lobes.

6. Calcarine fissure6. Calcarine fissure- found in the occipital - found in the occipital lobe perpendicular to lobe perpendicular to parieto occipital fissure parieto occipital fissure around which is the around which is the visual center.visual center.

LOBES OF THE CEREBRAL LOBES OF THE CEREBRAL CORTEXCORTEX

1. Frontal Lobe1. Frontal Lobe- includes all the - includes all the cortex lying anterior cortex lying anterior to the central sulcus to the central sulcus of Rolando and of Rolando and above the lateral above the lateral sulcus Sylviussulcus Sylvius- center for motor - center for motor functions and functions and personality personality

2. Parietal Lobe2. Parietal Lobe

- lies posterior to - lies posterior to central sulcus of central sulcus of Rolando and Rolando and above lateral above lateral Sylvian Sylvian

fissure.fissure.

- center for - center for sensory functionssensory functions

3. Temporal Lobe3. Temporal Lobe

- lies beneath the - lies beneath the lateral sulcus of lateral sulcus of SylvianSylvian

- center for - center for hearing and hearing and olfactionolfaction

4. Occipital Lobe4. Occipital Lobe

- occupies the - occupies the posterior posterior extremity of the extremity of the cerebral cerebral hemisphere hemisphere behind parieto-behind parieto-occipital fissureoccipital fissure

- visual center- visual center

5. Insula ( Island of Reil)5. Insula ( Island of Reil)

- exposed when - exposed when the lips of lateral the lips of lateral Sylvian fissure are Sylvian fissure are separatedseparated

FUNCTIONS OF THE CEREBRUMFUNCTIONS OF THE CEREBRUM

1. seat of advanced intellectual functions 1. seat of advanced intellectual functions like memory storage, recall, learning like memory storage, recall, learning and reasoning for comprehension and and reasoning for comprehension and execution of language.execution of language.

2. perception of all sensations and sites 2. perception of all sensations and sites where one modality of sensation can where one modality of sensation can be integrated with others.be integrated with others.

3. initiation of movements3. initiation of movements

FUNCTIONAL AREAS OF THE FUNCTIONAL AREAS OF THE CEREBRUMCEREBRUM

1.1. Primary Motor Area or Primary Motor Area or Pre-central gyrusPre-central gyrus

- lies in the frontal lobe - lies in the frontal lobe immediately anterior to immediately anterior to the central sulcusthe central sulcus- controls voluntary - controls voluntary movements in the opposite movements in the opposite side of body.side of body.- the body is represented - the body is represented with head down and lower with head down and lower extremities up and extremities up and medially in the cerebrum.medially in the cerebrum.- Brodmann's area 4- Brodmann's area 4

2. Pre-motor Area2. Pre-motor Area

- in front of the - in front of the motor areamotor area- exerts a - exerts a controlling controlling influence over the influence over the motor area, motor area, ensuring an orderly ensuring an orderly series of series of movements movements necessary for necessary for speech.speech.

3. Pre-frontal Area3. Pre-frontal Area

- concerned with - concerned with behavior, behavior, character and character and emotional state of emotional state of the individual.the individual.

- concerned with - concerned with foresight, good foresight, good judgment, abstract judgment, abstract thinking.thinking.

4. Primary sensory/Somesthetic 4. Primary sensory/Somesthetic Area or Post-central gyrusArea or Post-central gyrus

- lies behind the central - lies behind the central sulcus of Rolando in sulcus of Rolando in parietal lobeparietal lobe

- sensations of pain, - sensations of pain, temperature, temperature, pressure and touch, pressure and touch, position and position and movement sensation movement sensation from opposite side of from opposite side of body are received body are received and interpreted here.and interpreted here.

- Brodmann's area 3,1,2- Brodmann's area 3,1,2

5. Motor speech area5. Motor speech area

- lies in inferior - lies in inferior frontal gyrus of frontal gyrus of dominant dominant hemispherehemisphere

- Broca's area - Broca's area (Brodmann's area (Brodmann's area 45, 44)45, 44)

6. Sensory speech area:6. Sensory speech area:

- lies in temporal lobes - lies in temporal lobes posterior to auditory posterior to auditory area of dominant area of dominant hemispherehemisphere

- Wernicke's area - Wernicke's area (Brodmann's area (Brodmann's area 22)22)

7. Auditory or Hearing Area 7. Auditory or Hearing Area (transverse gyri of Heschl)(transverse gyri of Heschl)

- lies below lateral - lies below lateral sulcus within the sulcus within the temporal lobetemporal lobe

- center for hearing- center for hearing

- Brodmann's area 41 - Brodmann's area 41 & 42& 42

8. Visual area:8. Visual area:

- around the calcarine - around the calcarine fissure, including fissure, including greater part of the greater part of the occipital lobeoccipital lobe

- Brodmann's area 17- Brodmann's area 17

9. Olfactory or smell area9. Olfactory or smell area

- within the temporal - within the temporal lobelobe

10. Taste Area10. Taste Area

- above lateral sulcus - above lateral sulcus into the deep layers into the deep layers of the sensory areaof the sensory area

BASAL GANGLIABASAL GANGLIA

masses of gray matter masses of gray matter embedded in the white matter embedded in the white matter of the cerebral hemispheresof the cerebral hemispheres

- include the - include the caudate nucleuscaudate nucleus (medial portion) and the (medial portion) and the putamenputamen and and globus globus palliduspallidus called called lentiform lentiform nucleusnucleus..

- constitute the - constitute the corpus striatumcorpus striatum- Basal ganglia play a role in the - Basal ganglia play a role in the

control of motor function, and control of motor function, and injury produces unilateral or injury produces unilateral or bilateral tremor, rigidity and bilateral tremor, rigidity and uncontrolled aimless uncontrolled aimless movements.movements.

B. DIENCEPHALONB. DIENCEPHALON1. Thalamus1. Thalamus

- paired mass of gray matter situated - paired mass of gray matter situated below corpus callosum.below corpus callosum.- subcortical sensory integrating - subcortical sensory integrating cortexcortex

- relay center for sensory impulses - relay center for sensory impulses (except olfactory) from peripheral (except olfactory) from peripheral receptors to cerebral cortex; receptors to cerebral cortex; responsible for crude awareness of responsible for crude awareness of sensation sensation

- processes and relays coordinating - processes and relays coordinating motor impulses from the basal motor impulses from the basal ganglia and cerebellum to the ganglia and cerebellum to the cerebral motor cortex.cerebral motor cortex.

- relay and integration center for - relay and integration center for emotional behavioremotional behavior

2. Hypothalamus2. Hypothalamus

- involved in the - involved in the regulation of body regulation of body temperature, feeding temperature, feeding activities,concentration activities,concentration and volume of and volume of extracellular fluid, extracellular fluid, autonomic nervous autonomic nervous system responses, system responses, endocrine functions.endocrine functions.

2. MESENCEPHALON2. MESENCEPHALON

- - connects the connects the forebrain and forebrain and hindbrainhindbrain

- concerned with motor - concerned with motor coordinationcoordination

- connects the pons - connects the pons and the cerebellum and the cerebellum with the cerebrum with the cerebrum consists of:consists of:

a. Cerebral Peduncles (found anteriorly)a. Cerebral Peduncles (found anteriorly)- pair of cylindrical bodies made up of - pair of cylindrical bodies made up of

nerve nerve fiber fiber tracts which connect the tracts which connect the forebrain forebrain with the hindbrain.with the hindbrain.

b. Corpora Quadrigemina ( found posteriorly)b. Corpora Quadrigemina ( found posteriorly)- 4 rounded nuclear masses- 4 rounded nuclear masses1. superior colliculi1. superior colliculi

- upper 2; for visual reflexes- upper 2; for visual reflexes2. inferior colliculi2. inferior colliculi

- lower 2; for auditory reflexes- lower 2; for auditory reflexes

3. RHOMBENCEPHALON 3. RHOMBENCEPHALON CEREBELLUM ( Part of CEREBELLUM ( Part of

metencephalon )metencephalon )

- - oval in shape with a oval in shape with a central constriction and central constriction and lateral expanded lateral expanded portions.portions.

- the constricted central - the constricted central portion is called the portion is called the vermisvermis (Latin of worm) (Latin of worm) and the lateral and the lateral expanded portions the expanded portions the hemisphereshemispheres

- divided into lobes by deep - divided into lobes by deep and distinct fissures, and distinct fissures, these lobes include the:these lobes include the:

a. anterior \a. anterior \ concerned concerned with with

the function the function ofof

b. posterior /b. posterior / movementsmovements

c. flocculonocular lobesc. flocculonocular lobes

- concerned with the - concerned with the function of equilibriumfunction of equilibrium

PONS ( Part of metencephalon )PONS ( Part of metencephalon )

- - lies anterior to the lies anterior to the cerebellum and between cerebellum and between the midbrain and the midbrain and medulla.medulla.

- bridge-like structure, - bridge-like structure, consisting almost consisting almost entirely of white matter entirely of white matter linking the various parts linking the various parts of the brainof the brain

MEDULLA OBLONGATA MEDULLA OBLONGATA

( myelencephalon ( myelencephalon ))- - continuous with the spinal cord continuous with the spinal cord

inferiorly and with the pons inferiorly and with the pons superiorlysuperiorly

- lies ventral to the cerebellum- lies ventral to the cerebellum

- has a number of vital regulatory - has a number of vital regulatory and reflex centers, including and reflex centers, including those controlling the circulatory those controlling the circulatory system, breathing, swallowing, system, breathing, swallowing, vomiting, coughing, sneezing.vomiting, coughing, sneezing.

VENTRICLES OF THE BRAINVENTRICLES OF THE BRAIN- spaces inside brain filled with cerebrospinal fluid.- spaces inside brain filled with cerebrospinal fluid.- the Ventricular System includes:the Ventricular System includes:

1. lateral ventricle1. lateral ventricle- found inside the cerebral hemispheres- found inside the cerebral hemispheres- each lateral ventricle communicates with the third ventricle - each lateral ventricle communicates with the third ventricle

by way of an by way of an interventricular forameninterventricular foramen (foramen of (foramen of Monroe)Monroe)

2. third ventricle2. third ventricle- small, slitlike cavity in the center of the diencephalon in - small, slitlike cavity in the center of the diencephalon in

between the 2 thalamic continuous with the between the 2 thalamic continuous with the cerebral cerebral aqueduct of Sylviusaqueduct of Sylvius, a canal which passes through the , a canal which passes through the midbrain.midbrain.

3. fourth ventricle3. fourth ventricle- lies between the cerebellum on the posteriorly side and the - lies between the cerebellum on the posteriorly side and the

pons and medulla on the anteriorly side.pons and medulla on the anteriorly side.- communicates with subarachnoid space through Foramen - communicates with subarachnoid space through Foramen

of Luschka and Magendieof Luschka and Magendie

MENINGESMENINGES

--Three membranes collectively known as Three membranes collectively known as the meninges provide protectionthe meninges provide protection to to the brain and spinal cordthe brain and spinal cord

- from outside in, these are the:- from outside in, these are the:

A. Dura materA. Dura mater

B. Arachnoid materB. Arachnoid mater

C. Pia materC. Pia mater

A. DURA MATERA. DURA MATER

- the dura mater (latin for - the dura mater (latin for hard mother), the outer hard mother), the outer meninx, is made of meninx, is made of dense, fibrous tissue.dense, fibrous tissue.

- There are 2 portions of - There are 2 portions of the dura materthe dura mater

1. cranial1. cranial

2. spinal2. spinal

B. ARACHNOID MATERB. ARACHNOID MATER

- delicate serous membrane located between - delicate serous membrane located between the dura and pia.the dura and pia.

- As the name implies, it has the microscopic - As the name implies, it has the microscopic appearance of a spider webappearance of a spider web

- the cranial portion invests the brain loosely - the cranial portion invests the brain loosely and, with the exception of the longitudinal and, with the exception of the longitudinal fissure, it passes over the various fissure, it passes over the various convolutions and sulci and does not dip convolutions and sulci and does not dip down into themdown into them

C. PIA MATER C. PIA MATER

- The pia mater (gentle mother) is a vascular - The pia mater (gentle mother) is a vascular membrane consisting a plexus of fine blood membrane consisting a plexus of fine blood vessels held together by areolar connective vessels held together by areolar connective tissue.tissue.

- The cranial portion invests the surface of the - The cranial portion invests the surface of the brain and dips down into the sulci.brain and dips down into the sulci.

CEREBROSPINAL FLUIDCEREBROSPINAL FLUID

- the cerebrospinal fluid circulating within - the cerebrospinal fluid circulating within the ventricles, the central canal of the the ventricles, the central canal of the spinal cord and also within the spinal cord and also within the subarachnoid space.subarachnoid space.

- colorless, with a composition similar to - colorless, with a composition similar to that of lymphthat of lymph

SPINAL CORDSPINAL CORD

- the elongated and almost - the elongated and almost cylindrical part of the CNS, cylindrical part of the CNS, which lies within the vertebral which lies within the vertebral canal.canal.

- is continuous with the medulla - is continuous with the medulla oblongata above and extends oblongata above and extends from the level of foramen from the level of foramen magnum to the lower border magnum to the lower border of 1st lumbar vertebra in of 1st lumbar vertebra in adult and level of L3 vertebra adult and level of L3 vertebra in children.in children.

- average length: 45 cm- average length: 45 cm

- - 2 enlargements:2 enlargements:1. cervical enlargement (where nerve supply of arms 1. cervical enlargement (where nerve supply of arms arises from)arises from)

- level of 4th cervical to 2nd thoracic vertebrae- level of 4th cervical to 2nd thoracic vertebrae2. lumbar enlargement (where nerve supply of legs arises 2. lumbar enlargement (where nerve supply of legs arises from)from)

- level of 10th thoracic vertebra; widest at the - level of 10th thoracic vertebra; widest at the 12th thoracic vertebra12th thoracic vertebra

- it narrows down as a - it narrows down as a conus medullaris,conus medullaris, where it where it gives rise to the thread-like filum terminale that gives rise to the thread-like filum terminale that

terminates in the first coccygeal vertebra.terminates in the first coccygeal vertebra.- the lumbar and sacral spinal nerves descend - the lumbar and sacral spinal nerves descend

along along the filum terminale in a bundle known as the the filum terminale in a bundle known as the cauda cauda equinaequina

PERIPHERAL NERVOUS SYSTEM: PERIPHERAL NERVOUS SYSTEM:

SPINAL AND CRANIAL NERVESSPINAL AND CRANIAL NERVES

I . SPINAL NERVESI . SPINAL NERVES

- a bundle of nerve fibers - a bundle of nerve fibers attached to spinal cordattached to spinal cord

- 31 pairs of nerves called spinal - 31 pairs of nerves called spinal nerves arise from the spinal cord nerves arise from the spinal cord along almost its entire length and along almost its entire length and emerge from the vertebral canal emerge from the vertebral canal through the intervertebral foraminathrough the intervertebral foramina

1. 1. dorsal rootdorsal root

- containing fibers of sensory - containing fibers of sensory neurons neurons

2. 2. ventral rootventral root

- containing fibers of motor neurons- containing fibers of motor neurons

- these 2 roots join together to form - these 2 roots join together to form spinal nerve spinal nerve

- There are - There are eighteight pairs pairs of of cervical spinal cervical spinal nerves,nerves, 12 thoracic, 12 thoracic, 5 lumbar, 5 sacral, 5 lumbar, 5 sacral, 1 coccygeal1 coccygeal

PLEXUSESPLEXUSES

- group of nerve fibers from ventral rami of cervical , lumbar and - group of nerve fibers from ventral rami of cervical , lumbar and sacral spinal sacral spinal

nerves. Posterior rami never form plexuses.nerves. Posterior rami never form plexuses.1. Cervical Plexus1. Cervical Plexus

- formed by the first 4 cervical nerves (C1C2C3C4)- formed by the first 4 cervical nerves (C1C2C3C4)- this supplies the back and sides of the head and the front of the - this supplies the back and sides of the head and the front of the

neckneck- gives off the phrenic nerve to the diaphragm- gives off the phrenic nerve to the diaphragm

2. Brachial Plexus2. Brachial Plexus- lower 4 cervical (C5C6C7C8) nerves and 1st thoracic (T1) - lower 4 cervical (C5C6C7C8) nerves and 1st thoracic (T1) supplies the skin and muscles of the upper limbsupplies the skin and muscles of the upper limb- gives off large nerves: circumflex, radial. median ulnar and - gives off large nerves: circumflex, radial. median ulnar and musculocutaneous nerves.musculocutaneous nerves.

3. Lumbar Plexus3. Lumbar Plexus

- from L1 -L4 spinal nerves- from L1 -L4 spinal nervesa. Obturator Nervea. Obturator Nerve

- arising from anterior division of L2L3L4 spinal nerves - arising from anterior division of L2L3L4 spinal nerves - supplies the muscles and skin on medial aspect of thigh- supplies the muscles and skin on medial aspect of thigh

b. Femoral nerveb. Femoral nerve

- arising from the posterior divisions of L2L3L4 spinal - arising from the posterior divisions of L2L3L4 spinal nervesnerves

- supplies muscles and skin on anterior aspect of the thigh- supplies muscles and skin on anterior aspect of the thigh

4. Sacral Plexus4. Sacral Plexus

- from L4L5S1S2S3 - from L4L5S1S2S3 spinal nervesspinal nerves

- the largest branch of - the largest branch of which is the sciatic which is the sciatic nerve (the largest nerve (the largest nerve in the body)nerve in the body)

The thoracic spinal nerves do not form plexuses.The thoracic spinal nerves do not form plexuses.T1 - T11 spinal nerves - INTERCOSTAL NERVEST1 - T11 spinal nerves - INTERCOSTAL NERVEST 12 spinal nervesT 12 spinal nerves - SUBCOSTAL NERVE- SUBCOSTAL NERVE

Sciatic Nerve divides into:Sciatic Nerve divides into:a. tibial nervea. tibial nerve- supplies most of the posterior thigh - supplies most of the posterior thigh muscles, posterior leg and sole by muscles, posterior leg and sole by

dividing dividing into medial and lateral plantar into medial and lateral plantar nervesnerves

b. common peroneal nerveb. common peroneal nerve- supplies short head of biceps femoris - supplies short head of biceps femoris

and and anterolateral leg and dorsum of the foot.anterolateral leg and dorsum of the foot.

II. CRANIAL NERVESII. CRANIAL NERVES

- The cranial nerves are 12 pairs of symmetrically arranged - The cranial nerves are 12 pairs of symmetrically arranged nerves attached to thenerves attached to the brain.brain.- The cranial nerve includes the following:- The cranial nerve includes the following:

1. Olfactory (I)1. Olfactory (I)2. Optic (II)2. Optic (II)3. Oculomotor (III)3. Oculomotor (III)4. Trochlear (IV)4. Trochlear (IV)5. Trigeminal ( V)5. Trigeminal ( V)6. Abducens (VI)6. Abducens (VI)7. Facial ( VII)7. Facial ( VII)8. Vestibulocochlear (acoustic) (VIII)8. Vestibulocochlear (acoustic) (VIII)9. Glossopharyngeal (IX)9. Glossopharyngeal (IX)10. Vagus (X)10. Vagus (X)11. Accessory (XI)11. Accessory (XI)12. Hypoglossal (XII)12. Hypoglossal (XII)

CLASSIFICATION OF CRANIAL CLASSIFICATION OF CRANIAL NERVESNERVES

SENSORY NERVESSENSORY NERVES

- carry impulses towards brain. Also - carry impulses towards brain. Also called called afferent fibersafferent fibers

- - cranial nerves I (olfactory), II (optic) cranial nerves I (olfactory), II (optic) and VIII (vestibulocochlear) and VIII (vestibulocochlear)

however carry only sensory fibers ( from however carry only sensory fibers ( from the nose, eye, and ear, respectively)the nose, eye, and ear, respectively)

MOTOR NERVESMOTOR NERVES

- carry impulses away from the brain. - carry impulses away from the brain. Also called Also called efferent fibersefferent fibers

- cranial nerves III (oculomotor), IV - cranial nerves III (oculomotor), IV (trochlear) and VI (abducens), which(trochlear) and VI (abducens), which

supply the eye muscles, XI supply the eye muscles, XI (accessory) and XII (hypoglossal), which(accessory) and XII (hypoglossal), which

innervates the tongue, have been innervates the tongue, have been described as purely motor nerves.described as purely motor nerves.

MIXED NERVESMIXED NERVES

- carry both sensory and motor nerve fibers- carry both sensory and motor nerve fibers

- cranial nerves V, VII, IX, X are mixed - cranial nerves V, VII, IX, X are mixed nervesnerves

AUTONOMIC SYSTEMAUTONOMIC SYSTEM

- The autonomic nervous system may be divided, both functionally The autonomic nervous system may be divided, both functionally and structurally into sympathetic and parasympathetic nervous and structurally into sympathetic and parasympathetic nervous divisions.divisions.

1. Sympathetic or Thoracolumbar Divisions1. Sympathetic or Thoracolumbar Divisions of the autonomic of the autonomic nnervous system arises from all the thoracic and the first ervous system arises from all the thoracic and the first

three lumbar segments of the spinal cord.three lumbar segments of the spinal cord.

2.2.Parasympathetic or Craniosacral DivisionsParasympathetic or Craniosacral Divisions of the autonomic of the autonomic nervous system arises from the third, seventh, ninth, and nervous system arises from the third, seventh, ninth, and tenth cranial nerves and from the second, third, and fourth tenth cranial nerves and from the second, third, and fourth sacral segments of the spinal cord.sacral segments of the spinal cord.

FUNCTIONS OF THE ANSORGAN SYMPATHETIC PARASYMPATHETIC

Eye

Iris

Ciliary muscle

Dilates pupil

Flattens lens

Constricts pupil

Bulges lens

Peripheral blood vessels

Salivary glands

vasoconstriction

Stimulates viscous ( mucous)

Vasodilatation

Stimulates serous

secretion

Lacrimal glands None Stimulates secretion

Sweat glands Copious sweating None

FUNCTIONS OF THE ANS

ORGAN SYMPATHETIC PARASYMPATHETIC

HEART

SA NODE

MUSCLE

Increased rate

Increased force of contraction

Decreased rate

LUNGS

Bronchi Dilation Constriction

Stomach

Wall

Glands

Dec. motility and tone;Stimulates secretion of alkaline juice with low enzyme activity

Increased motility

Stimulates secretion of acid with high enzyme activity

FUNCTIONS OF THE ANS

ORGAN SYMPATHETIC PARASYMPATHETIC

SUPRARENAL GLAND

MedullaSecretion of epinephrine

None

URINARY BLADDER

Wall

Sphincter

Inhibition

ExcitationExcitation

Inhibition

PENIS EJACULATION ERECTION

FUNCTIONS OF THE ANS

ORGAN SYMPATHETIC PARASYMPATHETIC

ARRECTOR PILI

MUSCLES OF HAIR FOLLICLES

CONTRACTION None

ARTERIOLES

Splanchnic region and skin

CONSTRICTION DILATATION

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