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 sub-cortical 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 Rehabilitation Science Dept. Dr. Nabila Tounsi

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 Goal-directed limb movements, e.g. reaching, manipulation Main path is rubrospinal 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 Rehabilitation Science Dept. Dr. Nabila Tounsi

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

Rehabilitation Science Dept. Dr. Nabila Tounsi