The Nervous System Anatomy Central Nervous System Peripheral Nervous System

1. The Nervous System
Anatomy
‫العالي‬ ‫الصحية‬ ‫المهن‬ ‫معهد‬
‫م‬‫المادة‬ ‫درس‬
‫م‬.‫إختصاص‬ ‫جامعي‬
‫الوهاب‬ ‫عبد‬ ‫نزار‬ ‫صـالح‬
‫تمـريض‬ ‫علــوم‬ ‫ماجـستير‬
Salah Nazar Abdulwahhab M.Sc. Nursing
www.slideshare.net
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3. Nervous System
Complex network of neurons that regulate body processes
The nervous system has two major parts:
Central Nervous System (CNS) ------- (Brain and Spinal cord)
Peripheral Nervous System (PNS) ------- (Somatic and Autonomic) Nervous System
Nerve cells are called (Neurons)
Each Neuron consist of :
1- Cell body
2- Axon: transmit impulses away from the cell body of a neuron
3- Dendrites: transmit impulses toward the cell body
Synapse: is small gap between the axon of one neuron and the dendrites or cell body of the next
Neuron.3

4. Nerve cell (Neuron)
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5. Types of Neuron
There are 3 types of Neurons:
1- Sensory neurons (afferent neurons): carry impulses from receptors to the central nervous
system
2- Motor neurons (efferent neurons): carry impulses from the central nervous system to the
effectors (muscles and glands)
- linked to skeletal muscles are called (somatic neuron)
- linked to smooth muscle, cardiac muscle and glands are called (visceral neuron)
3- Interneurons: completely found within the central nervous system.
They are arranged to carry only sensory and motor impulses or to integrate these functions.
Some interneurons in the brain are concerned with thinking, learning and memory.
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6. Sensory, Motor and Interneuron (Reflex Arc)
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7. Central Nervous System
Consists of brain and spinal cord that coordinating incoming and outgoing information
- Found along the mid-sagittal plane of the body.
- The brain is protected in the cranial cavity of the skull
- Spinal cord is surrounded by the vertebral column
- Cerebrospinal fluid (CSF) which protect and nourish the CNS [about 125 ml in any time and
about 500mL is generated every day]
- CSF occupies the subarachnoid space (between the arachnoid mater and the pia mater)
- Three protective membranes (Meninges) cover the brain and spinal cord
1. Dura Mater = the double external layer
2. Arachnoid Mater = the middle layer
3. Pia Mater = the internal layer7

8. Meninges
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9. The Brain
Brain : a mass of 100 billion neurons and trillions of synapses located inside the skull
The major parts of the brain are
1- CEREBRUM: The largest portion of the brain consists of two hemispheres that are connected
together at the corpus callosum.
The cerebrum consist of five lobes that are responsible for different brain functions
A- Frontal Lobe
B- Temporal Lobe
C- Parietal Lobe
D- Occipital Lobe
E- Limbic Lobe
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10. Lobes of the Brain
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11. The Brain – Cont.
2- CEREBELLUM: connected to the brainstem, situated inferior to the occipital lobes of the cerebrum
- Cerebellum is the center for body movement and balance by uses information about gravity and movement
from the receptors in the inner ears to regulate equilibrium
3- DIENCEPHALON: deep part inside the brain, surrounded by the cerebral hemispheres.
Containing
Thalamus : (inner room) in Greek, olive shaped structure deep in the brain at the top of the brainstem.
Thalamus is a gateway to the cerebral cortex and relay station to all sensory inputs pass through it to the
higher levels of the brain (cerebral cortex).
Hypothalamus: located below the thalamus.
Hypothalamus monitors water and hormone concentrations, body temperature.
It is associated with feelings of rage, aggression, hunger and thirst.
Hypothalamus connect between the nervous system and the endocrine system (hormones). The hypothalamus
has many connections with the pituitary gland and can produce and regulate hormones.
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12. DIENCEPHALON and BRAINSTEM
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13. The Brain – Cont.
4- BRAINSTEM:
- connects cerebrum with the spinal cord
controls the basic functions of life like : breathing, heart beats, swallowing, reflexes to sight or
sound, sweating, blood pressure, sleep, and balance
- Motor and sensory neurons travel through the brainstem allowing for the relay of signals
between the brain and the spinal cord.
- Most cranial nerves are found in the brainstem
Parts of the Brainstem:
A- Midbrain
B- Pons
C- Medulla Oblongata.
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14. Spinal Cord
Continuous above with the medulla oblongata, lies in the vertebral canal and extends from the
foramen magnum to the level of the second lumbar vertebrae
tapered tip of cord = (Conus medullaris)
Cauda equina: nerve roots extending below Conus medullaris
average length about 45 cm
Cylinder shape, flattened slightly
surrounded by three meninges and cerebrospinal fluid (CSF)
Spinal cord is a component of the CNS
while the spinal nerves are part of the PNS
Has two enlargements:
 Cervical Enlargement: supply upper limbs.
 Lumbosacral Enlargement: supply lower limbs
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15. Peripheral Nervous System (PNS)
Peripheral Nervous System include (Somatic Nervous System and Autonomic Nervous System)
PNS = visible bundles of all nerves branching out from brain and spinal cord to the all parts of the body
Types
- Sensory nerves – carry messages from body to brain (pain, pressure, temperature)
- Motor nerves – carry messages from brain to the body for responding
Peripheral Nervous System Consists of:
1- Cranial nerves: 12 pairs of nerves that branching out from the brain.
- The first two nerves (olfactory and optic) arise from the cerebrum
- Ten nerves branch out from the brain stem.
- The names of the cranial nerves relate to their functions
- Cranial Nerves identified in roman numerals (I-XII).
2- Spinal nerves: 31 pairs & their branches, carries messages to & from the spinal cord, Both sensory and motor nerves
31 spinal nerves:
 8 cervical
 12 thoracic
 5 lumbar
 5 sacral
 1 coccygeal
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The Cranial Nerves
No. Nerve Name Functions Type
I Olfactory Nerve Smell Sensory
II Optic Nerve Vision Sensory
III Oculomotor Nerve Eye movement; pupil constriction Motor
IV Trochlear Nerve Eye movement Motor
V Trigeminal Nerve Face sensation, Mastication Both
VI Abducens Nerve Eye movement Motor
VII Facial Nerve Taste and facial expression. Both
VIII Vestibulocochlear Nerve Hearing and balance Sensory
IX Glossopharyngeal Nerve Taste and gag reflex Both
X Vagus Nerve glands, digestion, heart rate and reflexes Both
XI Accessory Nerve Shoulders Shrug Motor
XII Hypoglossal Nerve Swallowing , Speech Motor

17. Autonomic Nervous System
- Control of involuntary or unconscious body functions.
divided into two branches
- Sympathetic nervous system: stimulate the body in times of stress and crisis (Emergency)
- Parasympathetic nervous system: counterbalance for the Sympathetic nervous system (Rest)
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18. Autonomic Nervous System
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19. Somatic Nerves System
- Somatic Nerves carry motor commands to skeletal muscles through the reflex arc.
- Sensory neurons relay information about environment (touch, temperature, pressure, pain) and
carry to CNS
- Motor neurons which start appropriate response
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20. Thank You
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