Скачать или смотреть Pyramidal Tracts: Corticospinal & Corticobulbar Pathways | Decussation & Clinical Signs

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In this high-yield neuroanatomy lesson, we break down the pyramidal (corticospinal & corticobulbar) tracts from origin in the primary motor cortex to synapse on lower motor neurons. You’ll see where fibres travel (corona radiata → internal capsule → cerebral peduncles → medullary pyramids) and how decussation determines ipsilateral vs contralateral deficits.

What you’ll learn:
1. Lateral vs Anterior Corticospinal: fine distal control vs axial/proximal (gross) movement; 90% decussate at pyramids, 10% anterior cross segmentally
2. Corticobulbar rules: bilateral innervation (V, nucleus ambiguus) vs mixed innervation (VII upper face bilateral; lower face contralateral) and XII contralateral to genioglossus
3. Lesion patterns: internal capsule stroke, UMN facial weakness sparing the forehead, LMN/Bell’s palsy complete hemiface, tongue deviation (UMN → away, LMN → toward lesion)

⏱️ Timestamps
0:00 – Intro
0:19 – What are the pyramidal tracts? (Corticospinal & Corticobulbar)
0:38 – Functions of lateral vs anterior corticospinal tracts
1:08 – Lateral corticospinal: fine motor control (hands & feet)
1:31 – Anterior corticospinal: trunk & proximal limb movements
1:59 – Medullary pyramids & decussation (90% lateral, 10% anterior)
2:45 – Lateral corticospinal pathway step by step
3:42 – Anterior corticospinal pathway step by step
4:33 – Comparing decussation patterns (medulla vs spinal level)
5:04 – UMN vs LMN lesion patterns in corticospinal pathways
6:22 – Corticobulbar tract overview
7:22 – Trigeminal motor nucleus (muscles of mastication)
9:03 – Testing trigeminal motor function (jaw protrusion)
10:09 – Facial nerve corticobulbar pathway explained
11:34 – Rostral vs caudal facial subnuclei (forehead vs lower face)
12:52 – UMN lesion effect on facial muscles (forehead sparing)
13:51 – LMN lesion / Bell’s palsy effect on entire ipsilateral face
16:20 – Nucleus ambiguus pathway (IX & X → palate, pharynx, larynx)
17:47 – UMN vs LMN lesions in nucleus ambiguus (gag reflex, speech)
19:21 – Hypoglossal nerve corticobulbar pathway (tongue)
20:36 – Tongue deviation: UMN vs LMN lesion differences
21:23 – Summary & how to problem-solve lesion localization


This lesson is especially helpful for medical students, or anyone reviewing for anatomy exams.

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