Extrapyramidal Tracts Extra Pyramidal Tracts Include all motor

Extrapyramidal Tracts

Extra Pyramidal Tracts. Include all motor Tracts other than Pyramidal Tract. • Rubrospinal Tract • Reticulospinal Tract • Vestibulospinal Tracts • Tectospinal Tract • Olivospinal Tract • Medial longitudinal Bundle. About all these Tracts U must Know: 1. Origin 2. Course. 3. Relay & Functions

Rubrospinal tract Origion: Red Nucleus in the mid brain- (Magnocellular Part) Course: Cross to opposite Side forming Ventral Tegmental Decussation. Descend through pons & medullary reticular formation. Relay. Mostly on ά-motor neurons through Internuncial Neurons Functions: - Control Mainly crude movements. - Facilitate flexor muscles tone

Reticulospinal Tract Origion: two Types. – 1. Anterior-(Pontine) – 2. Lateral ( Medullary) Majority of Fibers do not Cross to the opposite side after their Origin. -Fibers of Ant. Tract (Pontine) are Situated Lateral to the anterior Corticospinal tract in the spinal cord. - Mostly end on gamma Motor Neurons. Function: Facilitatory to gamma motor Neurons Supplying Muscle Spindles (Self Excitatory)Hence involved in Muscle Tone

Lateral (Medullary) Reticulospinal Tract Arises from Medullary Reticular formation. Under the control of : 1. Cerebral cortex 2. Cerebellum 3. Basal ganglia Situated in the Anterior Part of Lateral Funiuculus • Mostly Uncrossed Function: Inhibitory to gamma Motor Neurons supplying Muscle Spindles. BALNCE B/W Excitation & Inhibition

Facilitation & Inhibition of Stretch Reflex (Reticulospinal Tract) by different Brain Areas 1. Motor Cortex 2. Basal Ganglia 3. Cerebellum 5. (Pontine)Excitatory Reticular Formation 6. (Medullary) Inhibitory Ret. formation

Tectospinal Tract • Origin: Arises from Tectum (Sup. & Inf. Colliculi) • Decussate to opposite side forming Dorsal Tegmental decussation • Descend in the spinal cord in & relay at diff. Levels Functions: Mainly Concerned with Reflex & Postural movements of Head & Neck in response to Visual & Auditory Stimuli

Olivospinal Tract Origin: Arises from inferior Olivary nucleus in the Medulla Oblongata. Crosses to the opposite side Descends in lateral white funiculus of the spinal cord. Fibers descend in the spinal cord but don’t relay below cervical segments. • Functions: Control of movements in response to proprioceptive stimuli

Medial longitudinal Fasciculus • Mixed Origin. • Originates a little above the Mid Brain from Interstitial , superior Colliculi, vestibular Nuclei • Descends on the medial side in Post. Part of Ant. Funiculus. • Includes fibers from 3 rd. 4 th & 6 th Cranial nerves Nuclei, & Auditory Nuclei. • Regulates Coordination of Reflex Movements related to Eye, Neck & other parts of the body.