Transcript Motor System Won Taek Lee, M.D. Ph.D. Department of Anatomy, Yonsei University College of Medicine.

Motor System
Won Taek Lee, M.D. Ph.D.
Department of Anatomy, Yonsei University College of Medicine
Elements of Motor System
Effectors
Skeletal Muscle
Smooth Muscle
Glands
MOTOR SYSTEM
SOMATIC MOTOR SYSTEM
AUTONOMIC MOTOR SYSTEM
(sympathetic and Parasympathetic)
Somatic
Motor
System
Autonomic
Motor
System
sympathetic
response
Somatic Motor System
Upper Motor Neuron
Auxiliary
Motor Pathways
descending
pathways from
brain stem
pyramidal
tract
Lower Motor Neuron
motor nerve
Skeletal Muscle
reflex
arc
LOWER MOTOR NEURON
Spinal Cord
Anterior Horn Cell (Lamina IX) -------- spinal n.
Brain Stem
General Somatic Efferent (GSE) Nuclei
Hypoglossal Nucleus -------------------Abducens Nucleus -----------------------Trochlear Nucleus ------------------------Oculomotor Nucleus ----------------------
XII
VI
IV
III
Special Visceral Efferent (SVE) Nuclei
Ambiguus Nucleus ----------------------- IX, X, XI
Facial (Motor) Nucleus ------------------- VII
Trigeminal Motor Nucleus -------------- V
Anterior Horn Cell
- Lower Motor Neuron -
AHC
Lower Motor Neuron
cell body: anterior horn
axon: anterior root,
spinal nerve
axon terminal:
neuromuscular
junction
Effector:
skeletal muscle
Spinal Cord
• anterior root:
- motor
• posterior root:
- sensory
Law of
Bell-Magendie
Lower Motor Neuron
M
N
Neuromuscular
Junction
(Myoneural Junction,
Motor End Plate)
M
NMJ
N
Neuromuscular Junction
MYASTHENIA GRAVIS
Defects in Neuromuscular
Transmission
before treatment
after treatment
• muscle weakness
which is greatly
increased by exertion or
repeated contraction
• autoimmune disease
with autoantibodies
against Ach receptor
• maybe fatal if untreated
by respiratory paralysis
• treated with
AchT inhibitors,
thymectomy, and
corticosteroids
EFFECTOR
Skeletal Muscle
Upper
Motor
Neuron
corticospinal
tract
Pyramidal
Tract
corticobulbar
tract
Albertus Magnus
(1206-1280)
Phrenology of Gall (1758-1828)
and Spurzheim (1776-1832)
Motor Homunculus
Somatic Motor System
Descending
Brain Stem
Pathways
Upper Motor Neuron
UMN
pyramidal
tract
Final Common Pathway
VOLUNTARY CONTROL
LMN
Lower Motor Neuron
motor nerve
Skeletal Muscle
AUTOMATIC
MOTOR
CONTROL
reflex arc
Upper Motor Neuron
Pyramidal Tract
Corticospinal Tract
Origin: Cerebral Cortex
Brodmann Area 4 (Primary Motor Area, M I)
Brodmann Area 6 (Premotor Area, PM )
Brodmann Area 3,1,2 (Primary Somesthetic Area, S I)
Brodmann Area 5 (Anterior Portion of Sup. Parietal Lobule)
Corona Radiata
lnternal Capsule, Posterior Limb
Crus Cerebri, Middle Portion
Longitudinal Pontine Fiber
Pyramid - pyramidal decussation
Corticospinal Tract - Lateral and Anterior
Termination: Spinal Gray (Rexed IV-IX)
Upper Motor Neuron
Pyramidal Tract
1. corona radiata
2. internal capsule,
posterior limb
3. crus cerebri
4. longitudinal
pontine fiber
5. pyramid
6. pyramid decussation
7. lateral corticospinal
tract
8. anterior corticospinal
tract
Upper Motor Neuron
Pyramidal Tract
1. corona radiata
2. internal capsule
3. crus cerebri
4. pontine longitudinal fiber
5. pyramid
6. pyramid decussation
7. lateral corticospinal tract
8. anterior corticospinal tract
Upper Motor Neuron
Corticospinal Tract
Corticospinal
Tract
• completion of
myelination in
2nd year of life
• time of
standing and
walking
Corticospinal tract
myelination
Upper Motor Neuron
Pyramidal Tract
Corticobulbar Tract
- Corticofugal fibers projecting to, and terminating in
the portions of lower brainstem
- Termination:
1) motor nuclei (upper motor neuron pathway)
hypoglossal, ambiguus, facial motor,
trigeminal motor, abducens, trochlear
and oculomotor nucleus
2) sensory relay nuclei
nuclei gracilis and cuneatus, trigeminal
sensory nucleus, solitary tract nucleus
3) reticular formation (corticoreticular fiber)
Upper Motor Neuron
Pyramidal Tract
Corticobulbar Tract (UMN Pathway)
- Corticofugal fibers projecting to, cranial motor nuclei
GSE - hypoglossal (XII), abducens (VI),
trochlear (IV) and oculomotor (III) nucleus
SVE - ambiguus (IX, X, XI), facial motor (VII),
trigeminal motor (V) nucleus
- largely bilateral
laryngeal, pharyngeal, palatal and upper facial
muscles of mastication and extraocular muscles
- unilateral
lower facial musculature (facial palsy)
SCM and trapezius (uncrossed) --- spinal accessory
- Pseudobulbar Palsy --- syndrome of bilateral UMN lesion
Upper Motor Neuron vs Lower Motor Neuron Syndrome
LMN syndrome
UMN Syndrome
Type of Paralysis
Flaccid Paralysis
Spastic Paresis
Atrophy
Severe Atrophy
No (Disuse) Atrophy
Deep Tendon Reflex
Absent DTR
Increase
Pathological Reflex
Absent
Positive Babinski Sign
Superficial Reflex
Present
Absent
Fasciculation and
Could be
Absent
Fibrillation
Present
UMN and LMN Syndrome - Paralysis
Upper Motor Neuron
Syndrome
Spasticity
- Increased resistance to passive movement in
antigravity muscle (flexor in arm, extensor in leg)
Clasp Knife Phenomenon
- Sign of Upper Motor Neuron Syndrome,
especially internal capsule lesion
cf. Rigidity
- increased muscle tone, no increased DTR
Cogwheel Phenomenon
- symptom of basal ganglia or cerebellar lesion
LMN Syndrome - Muscular Atrophy
UMN syndrome
BABINSKI SIGN
Dorsiflexion of great toe and
Fanning of other toes
associated with plantar flexion
on mechanical stimulation of
the outer edge of the
sole of the foot.
(Extensor Plantar Response)
UMN Syndrome – Increased Deep Tendon Reflex
Deep Tendon Reflex
(Knee Jerk)
 Increased DTR
is characteristic sign
of UMN syndrome
 Monosynaptic reflex
 Patellar tendon
stretch receptor to
anterior horn cell
 Quadriceps
contraction
LMN Syndrome – Fasciculation and Fibrillation
Electromyography (EMG)
Hypersensitivity to circulating acetylcholine
LMN syndrome and UMN Syndrome
Predominantly Motor Syndromes
• Poliomyelitis (Infantile Paralysis)
- viral infection of lower motor neuron
- LMN syndrome at the level of lesion
• Amyotrophic Lateral Sclerosis (ALS)
- combined LMN and UMN lesion
- LMN syndrome at the level of lesion
- UMN syndrome below the level of lesion
- Lou Gehrig’s disease in USA
Spinal Cord
Syndrome
1. corticospinal
tract (UMN)
2. lower motor
neuron (LMN)
Amyotrophic Lateral Sclerosis
Spinal cord of amyotrophic lateral sclerosis
*
*
*
*
*
*
Motor
Syndrome
Amyotrophic
Lateral Sclerosis
(ALS)
Lou Gherig’s
Disease
Lou "The Iron Horse" Gehrig (1903-41)
3.40, 2131(1925-39), 23 GSH, 147 RBI avg.
Spinal Cord
Syndrome
Amyotrophic
Lateral Sclerosis
(ALS)
Lou Gehrig’s
Disease
Stephen Hawking (1946- )
British Physicist, A Brief History of Time
Facial Palsy
(Bell’s Palsy)
Lower Motor
Neuron
Syndrome
Triple W Sign - Wrinkle, Wink, Whistle
Central Type
Facial Palsy
Upper Motor
Neuron
Syndrome
facial motor nucleus neurons
supplying forehead muscle
Bilateral Corticobulbar Tract
APRAXIA – Cortical Lesion
• Inability to properly
execute a learned
skilled movement
• Absence of paralysis
• Caused by lesions in
1. Premotor Area
2. Corpus Callosum
3. Parietal somesthetic
association area
(storage of body
image)
Somatic Motor System
Descending
Brain Stem
Pathways
Upper Motor Neuron
UMN
pyramidal
tract
Final Common Pathway
VOLUNTARY CONTROL
LMN
Lower Motor Neuron
motor nerve
Skeletal Muscle
AUTOMATIC
MOTOR
CONTROL
reflex arc
Pyramidal Tract and Associated Circuits
Upper Motor Neuron
UMN
BASAL
GANGLIA
CEREBELLUM
Lower Motor Neuron
lower motor neuron
LMN
Cerebellum
Basal
Ganglia
Somatic Motor System
Descending
Brain Stem
Pathways
Upper Motor Neuron
UMN
pyramidal
tract
Final Common Pathway
VOLUNTARY CONTROL
LMN
Lower Motor Neuron
motor nerve
Skeletal Muscle
AUTOMATIC
MOTOR
CONTROL
reflex arc
AUTOMATIC MOTOR CONTROL
Spinal Cord Level:
- Spinal Reflex : Monosynaptic & Polysynaptic
Brain Stem Level:
Reticulospinal Pathways
Lateral and Medial Reticulospinal Tract
Ventromedial Pathways
Tectospinal Tract
Vestibulospinal Tract
MLF (medial longitudinal fasciculus)
Posterolateral Pathways
Rubrospinal Tract
Brain Stem
Automatic Motor Control
Dorsolateral and Ventromedial Motor Pathways
Dorsolateral (Motor) Pathway
Rubrospinal Tract
Ventromedial (Motor) Pathway
Tectospinal Tract
Vestibulospinal Tract
MLF (Medial Longitudinal Fasciculus)
- interstitiospinal tract
Automatic
Motor
Control
Descending
Motor
Tracts
from
Brain Stem
ventromedial
pathway
dorsolateral
pathway
AUTONOMIC
MOTOR
SYSTEM
Sympathetic
Division
Parasympathetic
Division
AUTONOMIC MOTOR SYSTEM
Descending
HYPOTHALAMUS
Preganglionic Neuron
Autonomic Pathway
Preganglionic Fiber
Postganglionic Neuron
Ach
Postganglionic fiber
Ach & NE
Smooth Muscle & Gland
HYPOTHALAMUS
Descending
Autonomic Pathway
Preganglionic Neuron
Parasympathetic
AUTONOMIC
MOTOR
SYSTEM
Ach
Intramural ganglia
Cranial ganglia
Sympathetic
Ach
Paravertebral ganglia
Prevertebral ganglia
Postganglionic Neuron
Ach
NE
Effectors: Smooth Muscle & Gland
AUTONOMIC MOTOR SYSTEM
Spinal Cord
- Intermediolateral Cell Column
Sympathetic: T1-L3
Parasympathetic: S2-S4
Brain Stem
Parasympathetic (GVE)
Dorsal Motor Nucleus of Vagus -------Inferior Salivatory Nucleus -------------Superior Salivatory Nucleus -----------Edinger-Westphal Nucleus---------------
X
IX
VII
III
Sympathetic
Parasympathetic
Sympathetic
Parasympathetic
Cardiovascular system
blood vessels
to skeletal muscle
to skin and viscera
Heart
rate, force of contraction
Respiratory system
diameter of air passages
respiratory rate
Eye
accommodation
Sweat gland
Adrenal gland
none
vasodilation
vasoconstriction
increases
decreases
increases
increases
dilate pupil
distance vision
increased secretion
secretes E, NE
decreases
decreases
constrict pupil
near vision
none
none
Sympathetic
Parasympathetic
Digestive system
general level of activity
sphincters
secretory glands
salivary gland
Urinary system
kidneys
urinary bladder
sphincter
Male reproductive system
decreases
constrict
inhibit
stimulate
serous secretion
increases
dilate
stimulate
simulate
watery secretion
decreases urine
relaxes
constricts
increases
glandular secretion
and ejaculation
increases urine
tenses
relaxes
erection
Sympathetic Response
- fight of flight reaction
• increases blood supply
to skeletal muscle
• increases heart rate
• increases diameter of
air passages
• increases rate of respiration
• dilate pupil
• secrets epinephrine and
norepinephrine
• decreases blood to viscera
• constricts bladder sphincter
• increases sweat production
• constrict arrector pili muscle
Parasympathetic
Response
- energy conservation for
emergency situation
• increases general activity of
digestive system
• increases secretion of
digestive glands
• increases urine production
and relaxes sphincter
• erection
• decreases diameter of
air passages
• decreases respiratory rate
• constricts pupil