Download RHS 332-chap 2 part

Extrapyramidal
pathway
Dr nabila tounsi
Extra-pyramidal tracts
are all descending tracts,
- Origin: start nearly from most areas of the CC mainly from area
6, 8,1,2 , area 3,and also area 5,but with connection with other subcortical areas : basal ganglia, reticular formation, vestibular nuclei,
red-nuclei and olivary nuclei.
-
Types of extrapyramidal tracts: Rubro-spinal
tract , Tecto-spinal tracts, Reticulo-spinal tracts, Vestibulo-spinal
tracts , Olivo-spinal tract
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Anatomy review: Basal ganglia
Basal ganglia consists of a group of subcortical nucleis:
Striatum(= caudate,+ putamen), globus pallidus (= pallidum)
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Anatomy review: Basal ganglia
Input:
striatum
{
Output: globus pallidus & substantia nigra
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Basal ganglia

Composed of caudate nucleus + lentiform
nucleus:
Striatum = caudate nucleus + putamen.
Pallidum = globus pallidus.
Putamen + globus pallidus = lentiform nucleus.


Controls large subconscious movements of the
skeletal muscles.
The globus pallidus regulates muscle tone.
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Circuitry of the basal ganglia
Cerebral cortex
Motor areas
Caudate/Putamen
Globus
pallidus
(external)
Subthalamic
nucleus
Spinal
cord
Excitatory
Rehabilitation Science Dept.
Thalamus
dopamine
Substantia
nigra pars
compacta
Inhibitory
glutamateDr. Nabila Tounsi
GABA
Globus
pallidus
(internal)
Substantia
nigra pars
reticulata
Direct Basal Ganglia Circuit

Motor cortex projects to putamen:
Excitatory (glutamate)

Putamen projects to output nuclei (globus
pallidus internus and substantia nigra
reticularis):
Inhibitory (GABA and substance P)
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Dopamine Neuronal System
Consists of nigrostriatal fibers
 From pars compacta of substantia nigra
 To striatum
 Dopaminergic

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Lateral brain stem pathways
Main path is
rubrospinal
Goal-directed limb
movements, e.g.
reaching,
manipulation
From red
nucleus
Crosses
midline in brain
stem
Influence distal
muscles
Rehabilitation Science Dept.
Dr. Nabila Tounsi
-Rubro-spinal tract:
Origin: From the red nucleus in the
midbrain. This tract crosses to the
opposite side and descends in the lateral
column of the spinal cord.
 Functions:
- Inhibitory to MT.
- It acts as an additional pathway for
transmission of the cortical motor orders to
the lower motor neurons.

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Medial brain stem pathways
Basic postural
control
Tectum
Tectospinal tract
Vestibular nucleus
Reticulospinal tract
Vestibulospinal tract
Influence axial &
proximal
muscles
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Tecto-spinal tracts: 1
-I) Lateral Tecto-spinal tract:
-Origin: Superior colliculus in the tectum of the midbrain (which receives visual
impulses) this tract crosses to the opposite side and descends in the
cervical segments of the spinal cord.
-Functions: It is responsible for visual attack and defensive
reactions.
Defensive reactions:
- Closure of the eyes, raising the hands in front of the face
and turning the head away to avoid the source of injury.
.
Attack reactions:
- Turning the head towards a beautiful sight.
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Tecto-spinal tracts: 2
-II) Ventral tecto-spinal tract:
-Origin: Inferior colliculus in the tectum of the midbrain (which receives
auditory impulses). This tract crosses to the opposite side and
descends in the cervical segments of the spinal cord.
-Functions: It is responsible for auditory attack and defensive reactions.
-Defensive reactions:
- Running away when a person hears the sound of a car behind him.
-Attack reactions:
- Turning the head towards the source of a familiar sound.
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Reticulo-spinal tracts
a) Lateral reticulo – spinal tract:
 Origin: Reticular formation in the medulla.
This tract crosses to the opposite side.
 Function: Inhibition of MT.
b) Ventral reticulo-spinal tract:
 Origin: Reticular formation in the pons.
The tract passes in the same side.
 Function: Facilitation of MT.
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Vestibulo-spinal tracts:
Origin: Vestibular nuclei in the medulla.
Both lateral and ventral vestibule- spinal
tracts pass in the same side of the spinal
cord.
 Functions: Facilitation of MT, control of
equilibrium, and maintain posture

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Olivo-spinal tract:
Origin: Inferior Olivary nucleus in the
medulla oblongata. This tract descends in
the same side of the spinal cord.
 Function: Facilitation of MT

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Functions of extra-pyramidal tracts:
1) Regulation of equilibrium and maintain
posture
 2) Fixation movements
 3) Associated movements
 4) Coordination of movements:

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Parkinson disease: Basal ganglia circuitry
Abnormal functioning
Cerebral cortex
Motor areas
Caudate/Putamen
Globus
pallidus
(external)
Subthalamic
nucleus
Excitatory
glutamate
Rehabilitation Science Dept.
Thalamus
dopamine
Substantia
nigra pars
compacta
Inhibitory
GABA
Dr. Nabila Tounsi
Globus
pallidus
(internal)
Substantia
nigra pars
reticulata
Extrapyramidal disorders


Basal nuclei set organism’s level of
responsiveness to stimuli.
Extrapyramidal disorders are associated with
basal nuclei pathology:
Negative symptoms of underresponsiveness:
Akinesias
i.e. Parkinson disease
Positive symptoms of over-responsiveness:
Choreas, athetoses, ballisms
i.e. Huntington’s chorea
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Parkinsonism
Parkinsonism: elderly; degeneration of basal
ganglia; bradykinesia, rigidity, resting tremor,
and impairments of posture, balance, and gait,
calcul, concentration
-MT: +++, plastic
-Akinesia
 LOCUS NIGER

Rehabilitation Science Dept.
Dr. Nabila Tounsi
Chorea


CHOREA: is Involuntary, rapid, irregular,
jerky movements; clinical feature of
Huntington’s disease.”
Cara by: hypotonia, bilateral, may be
interest the face, the neck, upper limb or
low limbs, or associate between those
Rehabilitation Science Dept.
Dr. Nabila Tounsi
chorea :2
1-Huntington’s disease: inherited; adults;
fatal; degeneration of basal ganglia and
cerebral cortex; dementia, chorea, and
disturbances of tone, posture, and gait.
2-Sydenham’s chorea: infectious; children;
self-limiting; rheumatic fever; chorea,
disturbances of balance and gait, and
impairments of speech and memory
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Athetosis
Or athetoid movements :
“Slow, involuntary, writhing, twisting, “wormlike”
movements; clinical feature of cerebral palsy.”
-Hypo or hypertonia
-Syncinesia: imitation of movement
-reflexes
- Choreoathetosis= Chorea + athetosis
Rehabilitation Science Dept.
Dr. Nabila Tounsi
Ballismus
-Ballismus: is Sudden, jerky, forceful, wild,
flailing, motions ,if interest one side of
the body= Hemiballismus
Rehabilitation Science Dept.
Dr. Nabila Tounsi
PART OF EPS
STRIATUM
CAUDATE NUCLEUS
GLOBBUS PALLIDUS
SUBTHALAMIC NUNCLEUS OF LUYS
SUBSTANTIA NIGRA
RED NUCLEUS
Rehabilitation Science Dept.
Dr. Nabila Tounsi
LESION
Chorea
Huntington Chorea
Rigidity
Ballismus or Hemiballismus
Parkinson’s Dse.
Chorea