Anatomy sheet 8 Flashcards
(14 cards)
Upper Motor Neurons
*Project انبثق to LMN
* Innervate á& ỳ motor neurons and inhibitory interneurons
* contine:
1- Reticular formation: reticulospinal tract
2- Vestibular nuclei: vestibulospinal tract responsible for maintaining the balance during movement
3- Superior colliculus: tectospinal tract التيك توك بالعالي والي مسؤول عن الراس وبؤبؤ العين is a part of the visual system
4- Red nucleus: rubrospinal tract
5- Motor cortex: corticospinal & corticobulbar tracts (+ corticorubral & corticoreticular)
Descending Tracts Classification
^Classical classification:
1~ Pyramidal system
Axons traverse the pyramids in medulla
Corticospinal axons
2~ Extrapyramidal system
Other descending tracts
Basal ganglia and their connections with motor region هاي زي التكامل بتعمل بتربط فوق وتحت
^ Functional classification:
1~Medial system
Innervate medial motor nucleus ,ventral bone
2~ Lateral system
Innervate lateral motor nucleus Peripheral muscle
Descending Tracts
1-Lateral pathway
*Terminate laterally in the ventral horn امامي
*Crossed
*distal limbs “legs” (initiation & fine movement)
*Damage ʹ weakness (if not completely damaged) or paralysis (if completely damaged)
*Contains
a-Lateral corticospinal tract
b-Rubrospinal tract “r >lateral”
2-Medial pathways
*Terminate Medially in the ventral horn
*Trunk & proximal limb movements
*Important in maintaining balance & position
*Mostly happened unconsciously
*Damage:Deficits in maintaining balance & posture
&Changes in muscle tone
*Contains:
1-Reticulospinal tract
2-Vestibulospinal tract
3-Tectospinal tract
4-Anterior corticospinal tract
Rubrospinal tract
1-From red nucleus
2-Crossed immediately لانه لون احمر ف بعبر بشكل فوري
3-lesions below the decussation (typically the spinal cord) will cause symptoms on the ipsilateral side
The Pyramidal (Corticospinal
& corticobulbar) Tract
*Origin ʹ cerebral cortex
>1/3 from primary motor cortex
>1/3 from premotor areas
>1/3 from primary somatosensory cortex
-Terminate in dorsal horn and brainstem
-Modify processing in the somatosensory pathways
Corticospinal Tract
*Axons pass through:
1-Corona radiata
2-Internal capsule (posterior limb)
3-Basis pedunculi/ crus cerebriʹ midbrain
4-Medullary pyramids
–Decussation
>Crossed ;Lateral corticospinal
>Uncrossed ;Anterior corticospinal tract
Lateral Corticospinal Tract Somatotopic Organization
ื The deepest area: The cervical area
ื The most superficial/ lateral area: the sacral area
ื Thus, the cervical area is more less likely to be injured in compared to the sacral area
Corticobulbar Tract
1-Same origin & course as corticospinals
2-Leave tract in brainstem “b&b”
3-Terminate in the cranial nerve nuclei
4-Bilateral in general
*Except to facial nucleus
*make crossover and control other side
what happen if occuer damage before and after decussation?
Lesions above the decussation will cause symptoms on the contralateral side of the body, whereas lesions below the decussation (typically the spinal cord) will cause symptoms on the ipsilateral side.
Reticulospinal Tract
لردات الفعل
1-From the reticular formation
2-Important influence on muscle activity and reflexes مفيد لردات الفعل
3-Controlled by cortex (corticoreticular)
4-Contains descending autonomic fibers controlled by thalamus
5-Crossed and uncrossed :bilaterall
يعني لوخربت وحده منلاقي وحدة
6- Two tracts
–Lateral reticulospinal tract ʹ from Medulla//inhibition
–Medial reticulospinal tract ʹ from Pons\ exitation
Vestibulospinal Tract
دهليز
-Importance in maintaining balance
-Influence axial muscles
-Uncrossed :becouse connect with cerebuluum and its ipsilaterall,its will control other side but indirect
-Medial & lateral vestibulospinal tracts
Tectospinal Tract
*Superior colliculus التيك توك بالعالي
*Terminate in the cervical regions لانه بدها تلعب بحركة الراس
*Head and eye ball movements in response to visual stimuli تيك توك زي حركة العين وبنتهي عند الراس
*Mostly crossed لانه التيك تز كله غلط x
*connected direct with 3,4,5 cranial nerve its oredy control in eye ball
Anterior Corticospinal Tract
*Similar to other medial pathways
*Terminate in the medial motor n.
*Except it is voluntary الشخص الامامي بتحرك يشكل طواعي
*Do not cross in pyramidal decussation
-May cross before termination
Lower Motor Neuron Lesion
- Flaccidparalysisor paresis (weakness)
- Hypo‐ or areflexia
- Decreased muscle tone
- Atrophy‐ muscle wasting
- Developsovertime (weeks)
- Fasciculations – smalltwitchesthatarevisibletothe eye
