Nervous system Is very much important in controlling all the voluntary and involuntary actions of all parts of the body.
The nervous system consists of a special type of cell—the
neuron or nerve cell.
Every neuron is made of a cell body (also called a soma),
dendrites and an axon. Dendrites and axons are nerve fibres.
PARTS OF NERVOUS SYSTEM,
1. Central Nervous system (brain
and spinal cord)
2. Peripheral Nervous system
A. 12
pairs of cranial and 31 pairs of spinal nerves
B. Afferent
(sensory) division
C. Efferent
(motor) division
I. Somatic - Voluntary movements
II. The autonomic nervous system (Cardiac, smooth Muscle, glands)
(Sympathetic and parasympathetic)
BRAIN – A mass of
12 billion neurons protected by cranial bones.
Parts of Brain
1. Cerebrum
2. Cerebellum
3. Brain-stem
4. Diencephalon
5. Ventricles
6. Meninges
The cerebrum is
the largest part of the brain, divided into right and left hemispheres
(the left side governs the right side of the body, the right side governs the
left side of the body)
There are four lobes in the cerebral hemisphere,
A. Frontal – voluntary motor control,
learning, planning, and speech
B. Parietal – sensory, distance,
size, shape, and intellectual processes
C. Occipital – vision
and visual memory
D. Temporal – auditory, olfactory,
speech, judgment, & reasoning
The cerebral cortex is the outer layer of grey
matter (short- and long-term memory) and cerebral medulla is the white matter
(conduction pathways). Corpus callosum is the large fibres that connect the two
hemispheres). Gyri and sulci are the elevation and depression on the brain
surface, Fissures are deep grooves.
Cerebellum: The RT
and LT hemispheres are connected by the central vermis. Outer grey, inner
white form the arborvitae. The function is the coordination, movement, posture,
balance, running and walking.
Brain stem: Consist
of three parts (Mid-brain, Pons and Medulla oblongata)
1. Mid-brain: The upper part of
the brain stem.
-
Controls postural reflexes and walking
-
Visual reflexes and auditory control
2. Pons – Two-way conduction pathway.
3. Medulla oblongata: The lowest part of
the brain-stem.
- 75% of nerve fibres cross here
- Controls vital functions (respiration and circulation)
Diencephalon: Area
between the cerebrum and the mid-brain
A. Thalamus - The relay
station for sensory incoming and motor outgoing impulses.
B. Hypothalamus - Controls appetite (hunger and thirst), Temperature control and regulates pituitary secretions.
Meninges: Three
membranous coverings the brain (Dura, Arachnoid, Pia).
A. Dura mater – strong
fibrous tissue, lines the skull bones
Epidural
space – between the bone and the dura mater.
Subdural
space – between the dura and arachnoid layers.
B. Arachnoid – resembles fine cobwebs with
fluid (CSF)
Subarachnoid space – between the arachnoid and pia layers
C. Pia mater –covers
the brain and spinal cord surface.
Cerebrospinal Fluid (CSF): Serves as
a shock absorber for the brain and spinal cord. It is clear, colourless, water,
glucose, protein, and WBC.
Provides nutrients and waste removal for brain tissues, 400-500 ml
produced daily, yet only 140 ml is in circulation, Circulates through the
ventricles and into the central canal and subarachnoid spaces, and is absorbed
back into the blood.
Ventricles: CSF-filled
spaces, the rich network of blood vessels and the choroid plexus. maintains
selective permeability to protect brain tissue. Foramen of Monro – connects the
lateral ventricles to the third ventricle, Aqueduct of Sylvius – connects the
third and fourth ventricle.
In the roof of the fourth ventricle are openings that allow the
CSF to move into the cisterna magna, a space behind the medulla that is
continuous with the subarachnoid space.
Spinal Cord: Medulla Oblongata continues as the spinal cord.
“H” - The grey matter of cell bodies of interneurons and motor neurons, divided into anterior, posterior, & lateral horns.
White matter surrounds grey “H”; divided into anterior, posterior,
and lateral columns. (Large bundles of nerve axons divided into smaller bundles
called tracts); ascending, descending and lateral organizational tracts.
Two bundles of nerve fibres called roots project from each side of the
cord, dorsal nerve root (sensory afferent fibres), dorsal root ganglion
(sensory cell bodies) and ventral nerve root (motor efferent fibres).
The nerve roots join together to form a single, mixed nerve called a spinal
nerve.
Peripheral Nervous System:
A. Cranial Nerves – 12 pairs
1. Olfactory – I: sensory, smell
2. Optic – II: sensory, vision
3. Oculomotor – III: motor,
eye movement and pupil
4. Trochlear – IV: motor,
eye movement, peripheral vision
5. Trigeminal – V: both,
face and head (motor & sensory)
6. Abducens – VI: motor,
abducts the eye
7. Facial Nerve – VII: both,
facial expression, taste, tongue movement.
8. Vestibulocochlear – VIII: sensory,
hearing and balance
9. Glossopharyngeal – IX: both,
tongue, throat, swallowing
10. Vagus – X: both, organ sense (thoracic
and abdominal) inhibitor
11. Accessory – XI: motor,
spinal accessory, shoulder and head movement
12. Hypoglossal – XII: motor,
tongue and throat movement
B. Spinal Nerves – 31 pairs
1. Cervical – 8
pairs
2. Thoracic
– 12 pairs
3. Lumbar –
5 pairs (Nerves exit the cord at the 1st lumbar vertebra, but do not exit
the spinal canal until reaching their intervertebral foramina; this gives the
cord a “cauda equina” look).
4. Sacral –
5 pairs
5. Coccygeal – 1 pair
Each nerve joins to form a network – Plexuses (Cervical, Brachial, Lumbar, and Sacral).
A dermatome is an area of skin that is mainly supplied by a single spinal nerve.
Upper extremity nerves
Lower extremity nerves
— Median nerve
Femoral nerve
— Ulnar nerve
Sciatic
nerve
— Radial nerve
Common peroneal nerve
Tibial
and Sural nerve
Common Disease of Nervous
System
1. Epilepsy - A disorder in which nerve
cell activity in the brain is disturbed, causing seizures.
2. Parkinson's disease - is a
long-term degenerative disorder of the central nervous system
3. Multiple sclerosis - is a
demyelinating disease in which the insulating covers of nerve cells in the
brain and spinal cord are damaged
4. Hemiplegia - Paralysis of one side of
the body. Hemiparesis - a weakness of the entire left or right side
of the body.
5. Alzheimer's disease - A
progressive disease that destroys memory and other important mental functions.
6. Encephalitis - Inflammation of the
brain, often due to infection.
7. Meningitis - is an acute inflammation
of the protective membranes covering the brain and spinal cord
8. Quadriplegia - total loss of use of all
four limbs
Common Signs and Symptoms of Nervous System
1. Pain
2. Inability to concentrate
3. Memory loss
4. Loss of muscle strength
5. Tremors
6. Slurred speech
7. Seizures
8. Paralysis
MEDICAL TERMS:
1.
Brain
- Encephalo
2.
Meninges -
Meningo
3. Spinal
cord - Myelo
4.
Nerve -
Neuro
5.
Cerebrum
- Cerebro
6.
Cerebellum - Cerebello
7.
Mind
-
Psycho, ment/o
8.
Head
- cephal/o
9. Nerve
root -
radic/o, radicul/o
10. Speech
- phas/o
11.
Sensation
- esthesi/o
SPECIAL SENSES
1.
Ear
-
Auri
2. Hearing
- Audio
3.
Eye
- Ophthalmo
4. Lens
- Phako
5. Eyelid
-
Blepharo
6. Pupil
- Coreo
7. Lip
- Cheilo / Labio
8. Cornea
- Kerato
9. Tympanic
membrane - Myringo
10. Fingernail /
Toenail - Onycho
MEDICAL ABBREVIATIONS:
1. ADD - Attention
deficit disorder
2. ADHD - Attention
deficit hyperactivity disorder
3. ANS - Autonomic
nervous system
4. CNS - Central nervous
system
5. CP - Cerebral palsy
6. CSF - Cerebrospinal
fluid
7. CVA - Cerebral
vascular accident,
8. EEG -
Electroencephalogram
9. HA – Headache
10. ICP - Intracranial
pressure
11. IQ - Intelligence
quotient
12. LOC - Level of
consciousness; loss of consciousness
13. MS - Multiple
sclerosis
14. PNS - Peripheral
nervous system
15. Sz - Seizure
16. TIA - Transient
ischemic attack
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Test your Knowledge:
A. Nervous System Anatomy Quiz