anatomy and physiology of Nervous system.ppt

Structure of synovial joint and muscle attachment

1. Nervous system

2. Nervous system is smallest and most complex of body
systems
Nervous system, along with endocrine system,
regulates functions of other body systems
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3. Organization
Nervous system is divided into:
I.Central nervous system
BRAIN
SPINAL CORD
II.Peripheral nervous system
CRANIAL NERVES (arising from brain)
SPINAL NERVES (arising from spinal cord)
Associated ganglias
Autonomic nervous systemis a functional subdivision of
nervous system
Peripheral portions of autonomic nervous system are subdivided
into sympathetic and parasympathetic divisions
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5. Major functions of nervous system:
Nervous system is specialized for perceiving and responding to
events in our internal and external environments
An awareness of one’s environment is made possible by
neurons
Neurons are highly specialized with respect to excitability and conductivity
Nervous system has the ability:
•to store experiences (MEMORY)
•to establish patterns of response on the basis of prior
experiences (LEARNING)
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6. Central nervous system
The entire delicate CNS is protected by :
fixed bony encasement craniumsurrounding brain
flexible vertebral column surrounding spinal cord
?Meninges
connective tissue encasements that form a protective membrane between
bone and soft tissue of CNS
oCNS is bathed in cerebrospinal fluid
CSF circulates within the:
•Hollow ventricles of brain
•Central canal of spinal cord
•Subarachnoid space surrounding entire CNS
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7. MENINGES
Has three layers (from outside to inside)
Dura Mater
Arachnoid Mater
Pia Mater
Dura Mater
Cranial dura mater:
•is composed primarily of dense connective tissue
•is a double-layered structure
•outer periosteal layer adheres lightly to cranium
•inner meningeal layer is thinner and follows general contour of brain
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Dural folds

10. Spinal dura mater
•is not double layered
•is similar to meningeal layer of cranial dura mater
•no connection between dural sheath and vertebrae forming
vertebral canal
Epidural space
•Potential cavity between dural sheath and vertebrae forming vertebral
canal
•Epidural space is highly vascular and contains loose fibrous and adipose
connective tissues (forms a protective pad around spinal cord)
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Epidural space

12. Arachnoid Mater
Is middle of the three meninges
It is delicate, netlike membrane spreads over CNS
Generally does not extend into sulci orfissures of brain
Subarachnoid space
•located between arachnoid mater and pia mater
•Contains cerebrospinal fluid
Pia Mater
•It is thin and tightly bound to convolutions of brain and
irregular contours of spinal cord
•It is highly vascular
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13. Cerebrospinal fluid (CSF)
•Clear, lymph like fluid
•Forms a protective cushion around and within the CNS
•Protects CNS from mechanical injury
•Helps to remove metabolic wastes from nervous tissue
Production
CSF is continuously produced by filtration of blood plasma
through masses of specialized capillaries called choroid
plexuses (to a lesser extent, by secretions of ependymal cells)
Choroid plexus situated in ventricles of brain
oUp to 800 ml of cerebrospinal fluid is produced each day
oApproximately 150ml of CSF circulates at given time
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14. ?Ventricles
CSF filled interconnecting spaces within substance of brain
•Lateral ventricles (each located in one of the hemispheres of cerebrum)
•3
rd
ventricle is located in diencephalon between the thalami
Each lateral ventricle is connected to third ventricle by a narrow, oval
opening called interventricular foramen (foramen of Monro)
•4
th
ventricle is located in brain stem between pons and
cerebellum
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Horizontal section of cranium
Lateral ventricle
Choroid plexus

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Lateral ventricles
Interventricular foramen
3
rd
ventricle
Cerebral aqueduct
4
th
ventricle
Central canal of spinal cord
Ventricles of brain (phantom view)

17. oMesencephalic aqueduct (cerebral aqueduct) passesthrough
midbrain to link 3
rd
and 4
th
ventricles
4
th
ventricle communicates posteriorly with central canal of
spinal cord
CSF exits from 4
th
ventricle into subarachnoid space through
three foramina:
oMedian aperture (foramen of Magendie)
oTwo lateral apertures (foramina of Luschka)
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20. BRAIN
Forebrain
-Cerebrum
-Diencephalon (thalamus, hypothalamus)
Midbrain
Hindbrain
-Pons
-Medulla oblongata
-Cerebellum
Mid Brain
Pons
Medulla oblongata
Brainstem

21. Cerebrum
Thalamus
Mid brain
Pons
Cerebelleum
Medulla oblongata
Hypothalamus

22. CEREBRUM
•Largest and most superiorly situated portion of brain
•Occupies most of the cranial cavity
•Consists of right and left hemispheres (incompletely separated by
a longitudinal cerebral fissure)
?Corpus callosum
Band of white fibres connecting cerebral hemispheres
Each cerebral hemisphere controls contralateral (opposite) side
of the body
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Supero lateral surface
Medial surface

24. CNS is composed of gray and white matter
Outer surface of cerebrum is called cortex ( cortex is also called
GREY MATTER)
Gray matter consists of:
•Nerve cell bodies
•Dendrites
•Bundles of unmyelinated axons
•Neuroglia
Cerebral cortex is characterized by numerous folds and
grooves called convolutions
•Elevated folds of convolutions are cerebral gyri
•Depressed grooves are called cerebral sulci
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25. Beneath cortex is medulla (often called WHITE MATTER of brain)
White matter forms tracts within CNS
? Tracts = Bundles of myelinated axonal fibers
•Specialized gray matter clusters of nerve cells called nuclei are
found deep within the white matter
White matter consists aggregations of:
•Dendrites
•Myelinated axons
•Neuroglia
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Cortex
Medulla
Nuclei

27. Lobes of Cerebrum
Each cerebral hemisphere is subdivided into five lobes by
deep sulci orfissures
Four of these lobes appears on surface of cerebrum and are
named according to overlying cranial bones
oFrontal lobe
oParietal lobe
oTemporal lobe
oOccipital lobe
Central sulcus separates frontal lobe from parietal lobe
Lateral sulcus separates frontal lobe from temporal lobes
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Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Central sulcus
Lateral sulcus
Precentral gyrus
Post central gyrus

29. Frontal lobe
•Initiates voluntary motor impulses for the movement of
skeletal muscles
•Provides responses relating to personality
Parietal lobe
•Responds to stimuli from cutaneous and muscular receptors
throughout the body
Temporal lobe
•Contains auditory centers that receive sensory fibers from
cochlea of the ear
•Stores memories of both auditory and visual experiences
Occipital lobe
•Concerned with visual perception
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30. Peripheral nervous system
Cranial and Spinal nerves
Consist of bundles of nerve fibers or axons
Surrounded by fibrous sheaths
Conduct information to and from central nervous system
Ganglia
Sensory ganglia of spinal nerves and cranial nerves
Autonomic ganglia
?Ganglia = collection of nerve cell bodies outside CNS

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Brain
Spinal cord
Cranial nerves
Spinal nerves
Ganglias

32. Cranial nerves
•12 pairs of cranial nerves
•Arises directly from base of brain
•Most of their nuclei are situated within substance of the brain
I . OLFACTORY NERVE (sensory)
II. OPTIC NERVE (sensory)
III.OCCULOMOTOR NERVE (motor)
IV. TROCHLEAR NERVE (motor)
V. TRIGEMINAL NERVE (sensory & motor)
VI. ABDUCENT NERVE (motor)
VII. FACIAL NERVE (motor & sensory)
VIII. VESTIBULOCOCHLEAR NERVE (sensory)
IX. GLOSSOPHARYNGEAL NERVE (motor & sensory)
X. VAGUS NERVE (motor & sensory)
XI.ACCESSORY NERVE (motor)
XII.HYPOGLOSSAL NERVE (motor)
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Inferior view of BRAIN

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Olfactory nerve

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Optic nerve

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Occulomotor nerve
Trochlear nerve
Abducent nerve

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Trigeminal nerve

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Facial nerve
Vestibulo cochlear nerve

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Glossopharyngeal nerve
Accessory nerve
Vagus nerve
Hypoglossal nerve

40. CEREBELLUM
•Consists of cerebellar hemispheres
•Inside the substance of cerebellum deep cerebellar nuclei are
present
•Each hemisphere controls ipsilateral side of the body
BRAIN STEM
Consists of:
•Mid brain
•Pons
•Medulla oblongata
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Mid Brain
Pons
Medulla oblongata
Cerebellum

42. Spinal cord
External Anatomy
•Roughly oval in shape, being flattened slightly anteriorly and
posteriorly
•In adults, it extends from medulla oblongata to superior
border of 2
nd
lumbar vertebra
•When spinal cord is viewed externally, two conspicuous
enlargements can be seen
Cervical enlargement
Lumbar enlargement
•Spinal cord terminates as a tapering, conical structure called
conus medullaris
•Arising from conus medullaris is filum terminale(an extension
of pia mater that extends inferiorly)
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44. Spinal nerves
Paths of communication between spinal cord and specific
regions of body
•31 pairs of spinal nerves emerge at regular intervals from
intervertebral foramina
There are
•8 pairs of cervical nerves (C1–C8)
•12 pairs of thoracic nerves (T1–T12)
•5 pairs of lumbar nerves (L1–L5)
•5 pairs of sacral nerves (S1–S5) and
•1 pair of coccygeal nerves (Co1)
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45. Two bundles of axons, called roots, connect each spinal nerve to
a segment of the cord by even smaller bundles of axons called
rootlets
•Posterior (dorsal) root and rootlets contain only sensory axons
•Each posterior root has a swelling, the posterior (dorsal) root
ganglion (contains cell bodies of sensory neurons)
•Anterior (ventral) root and rootlets contain axons of motor
neurons
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Dorsal root
Ventral root
Rootlets
Dorsal root ganglia

46. Internal Anatomy of spinal cord
Transverse section of spinal cord reveals regions of white matter
that surround an inner core of gray matter
•White matter of spinal cord consists primarily of bundles of
myelinated axons of neurons
•In Gray matter of spinal cord clusters of neuronal cell bodies
form functional groups called nuclei
•Gray matter on each side of spinal cord is subdivided into
regions called horns
•Posterior (dorsal) gray horns contain cell bodies and axons of
interneurons as well as axons of incoming sensory neurons
•Anterior (ventral) gray horns contain somatic motor nuclei
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48. Autonomic nervous system
•Involuntary effectors (Smooth muscle tissue, Cardiac muscle tissue,
and Glandular epithelium) are regulated by autonomic motor
impulses through autonomic nervous system
•ANS is composed of portions of both the central nervous
system and peripheral nervous system
•It functions independently (without a person’s conscious control)
Divisions:
Sympathetic (Thoracolumbar ) division
Parasympathetic (Craniosacral) division
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Autonomic nervous system

50. Sympathetic and parasympathetic divisions of ANS affect the
visceral organs in different ways
Mass activation of sympathetic division prepares body for
intense physical activity in emergencies
•Heart rate increases
•Blood glucose rises
•Blood is diverted to skeletal muscles
Theme of sympathetic division is aptly summarized in the phrase
fight orflight
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51. Sympathetic system activated

52. oEffects of parasympathetic nerve stimulation are in many
ways opposite to the effects of sympathetic stimulation
oParasympathetic division is not normally activated as a whole
Stimulation of separate parasympathetic nerves can result in
•Slowing of the heart
•Dilation of visceral blood vessels
•Increased activity of the GI tract
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53. Parasympathetic response

54. SENSATIONS
General senses include:
Somatic senses (tactile, thermal, pain, and proprioceptive)
Visceral sensations
receptors for general senses are scattered throughout the body
and are relatively simple in structure
Special senses includes:
Smell
Taste
Vision
Hearing & Equilibrium
receptors for special senses are anatomically distinct from one
another and are concentrated in specific locations in the head
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55. Olfaction: Sense of Smell
Gustation: Sense of Taste (only five primary tastes can be
distinguished: sour, sweet, bitter, salty, and umami)
Vision(More than half the sensory receptors in human body
are located in the eyes)
Hearing and Equilibrium
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