Decussation of the pyramids
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| Decussation of the pyramids | |
|---|---|
| Deep dissection of brain-stem. Lateral view. ("pyramidal tract" visible in red, and "pyramidal decussation" labeled at lower right.) | |
| Decussation of pyramids. Scheme showing passage of various fasciculi from medulla spinalis to medulla oblongata. a. Pons. b. Medulla oblongata. c. Decussation of the pyramids. d. Section of cervical part of medulla spinalis. 1. Anterior cerebrospinal fasciculus (in red). 2. Lateral cerebrospinal fasciculus (in red). 3. Sensory tract (fasciculi gracilis et cuneatus) (in blue). 3’. Gracile and cuneate nuclei. 4. Antero-lateral proper fasciculus (in dotted line). 5. Pyramid. 6. Lemniscus. 7. Medial longitudinal fasciculus. 8. Ventral spinocerebellar fasciculus (in blue). 9. Dorsal spinocerebellar fasciculus (in yellow). | |
| Latin | decussatio pyramidum |
| Gray's | subject #192 870 |
| Dorlands/Elsevier | d_04/12282126 |
The two pyramids contain the motor fibers which pass from the brain to the medulla oblongata and medulla spinalis, corticobulbar and corticospinal fibers. When these pyramidal fibers are traced downward it is found that some two-thirds or more of them leave the pyramids in successive bundles, and decussate in the anterior median fissure, forming what is termed the pyramidal decussation. Having crossed the middle line, they pass down in the posterior part of the lateral funiculus as the lateral cerebrospinal fasciculus.
[edit] External links
- Dictionary at eMedicine decussation+of+pyramids
- Anatomy Atlases - Microscopic Anatomy, plate 17.326 - "Medula Oblongata"
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