Download 14. Assessment of the nervous system

Assessment
of the nervous system
Functions of nervous system
The main function of nervous system is
unification and regulation of
different physiological processes.
That means that nervous system
unites, integrates and
subordinates all the parts of
human body and provides its
connection with environment
Functions of nervous system
The base of nervous system activity is
reflex principle
Reflex – is a reaction of our organism to
various outside and inside effects. It is
provided by nervous system
Reflex consists of:
afferent part (which accepts information)
central part (that keeps information)
efferent part (that creates response)
As a result we have a circle – like structure
- receptor (primary information centre) –
programme centre – executive apparatus
Reflex arch
Reflexes are divided into:
simple and complex
inborn and trained
conditioned and unconditioned
Unconditioned reflexes:
They are inborn ones
They are phylogenetically old, that means they
were formed in course of phylogenesis
They are based on certain anatomic structures
(segments of spinal cord or brain stem)
They exist even without brain cortex influence
They are inherited
They can be regulated by brain cortex
They are basis for the conditioned reflexes
Conditioned reflexes:
They are the result of the individual experience
and are formed during ontogenesis
They are unstable, that means they need
constant support
They aren’t based on certain anatomic
structures
They are fixed in brain cortex
There are such conditioned reflexes as speaking,
writing, reading, calculation, practice
Unconditioned reflexes
are divided into:
Superficial and deep
Simple and complex
Unconditioned reflexes are divided
into:
Proprioceptive (stretch, periosteal, joint)
Exteroceptive (dermal, from mucose
membrane)
Interoceptive (from mucosa membrane of
internal organs – for example urination in
case of internal sphincter irritation)
Motor System
Motor system
Provides conduction of nervous impulse
from brain cortex to muscles.
The way of this impulse is known as
motorway
or tractus corticomuscularis
It consists of two neurons:
Central – upper motor neuron (UMN)
Peripheral – lower motor neuron (LMN)
Upper and lower extremities, neck, trunk
and perineum muscles’ innervation
The first (central) neuron
(upper motor neuron)
is called Corticospinal tract
tractus corticospinalis
The second (peripheral) neuron
(lower motor neuron)
is called Spinomuscular tract
tractus spinomuscularis
Tractus corticomuscularis
Motor Homunculus
Upper Motor Neuron
Corticospinal Tract
Lower Motor Neuron
cell body: anterior horn
axon: anterior root,
spinal nerve
axon terminal:
neuromuscular
junction
Effector:
skeletal muscle
Spinal nerve gives 4 branches:
ramus anterior ( together they form plexus
– cervical, brachial, lumbar and sacral)
ramus posterior (it is spinal nerve, which
innervates posterior trunk muscles)
ramus meningeus
ramus comunicante albi
Conclusions:
The muscles of upper and lower
extremities have unilateral cortical
innervation from contralateral hemisphere
The muscles of neck, trunk and pelvic
organs have bilateral innervation from both
hemispheres. In case of unilateral
pathologic focus these structures do not
suffer
Extremities, neck, trunk and
perineum muscles’ innervation
Neurons of С1-С4 anterior
roots – innervate neck
muscles
С5-Th1 – muscles of upper
extremities
Th2-Th12 – muscles of
trunk
L1-S2 – muscles of legs
S3 – S5 – muscles of
perineum
Face, tongue and pharynx
muscles innervation
This way is called tractus corticomuscularis
The first central neuron
(upper motor neuron)
is called tractus corticonuclearis
(Corticobulbar Tract)
The second peripheral neuron
(lower motor neuron)
is called tractus nucleomuscularis
Face, tongue and pharynx muscles
innervation
We can make the following conclusions:
The face muscles have bilateral cortex
innervation except the mimic muscles and
tongue muscles that have unilateral
innervation from the opposite hemisphere
The muscles of upper and lower extremities,
lower mimic muscles and tongue muscles
have unilateral cortical innervation
All the other muscles (the muscles of neck,
trunk, perineum, m. oculomotorial, m.
masseter, pharyngeal and palatal muscles)
have bilateral cortical innervation
UMN and LMN Syndrome - Paralysis
Paralysis
Paralysis (plegia) - means the absence of
active movements. It occurs in case of
complete lesion of motor way (tractus
corticomuscularis)
Paresis occurs in case of incomplete
lesion of motor way. That means disorders
of active movements
Clinically can be – hemi-, tetra-, mono-, triand paraparesis
Paralysis is divided into:
Central (spastic)
Peripheral (flaccid)
Central or spastic paralysis is caused by the
lesion of central neuron and its fibers (tr.
corticospinalis or tr. corticonuclearis)
Peripheral or flaccid paralysis is caused by
the lesion of peripheral neuron (tractus
spinomuscularis or tractus
nucleomuscularis)
Features of central (spastic)
paralysis are:
1. Hyperreflexion of Deep Tendon reflexes
2. Spasticity of skeletal muscles
3. Pathologic reflexes. They are considered
to be reliable signs of central paralysis
4. It is a diffuse paralysis
5. Protective reflexes (the reflexes of spinal
automatism)
6. Pathologic synkinesis is involuntary
movements in paralysed extremity
Spastic hypertonus (Vernike-Mann posture)
Spastic hypertonus features:
Tonus is increased in the group of flexors
in upper extremities and in the group of
extensors in lower extremities
“Clasp – knife“ Phenomenon
in course of evaluation tonus decreases
Spastic hypertonus in leg
Planter response
Normal
Pathologic
Features of peripheral paralysis
1. Areflexion or hyporeflexion
2. Atonia or hypotonia
3. Muscular atrophy
4. Fasciculation of muscles
5. It is limited paralysis
6. There is reaction of degeneration
Global
wasting of
the left arm
in a posttraumatic
brachial
plexopathy
Muscular Atrophy
Wasting of the tongue
Note any of the following
common gait disorders:
Hemiplegic gait with one-sided weakness
- a possible sign of cerebral stroke
Spastic gait - a possible sign of cerebral
palsy
Ataxic gait - a possible indication of
cerebellar dysfunction
Festinating gait - a possible sign of
Parkinson's disease
Bare test (upper)
Bare test (upper)
Bare test (lower)
Mandibular reflex
Palatal reflex
Biceps reflex
Triceps reflex
Carpo-radial reflex
Knee reflex
Ankle reflex