Somato 1: DCMLS Flashcards
DCMLS Characteristics
Large myelinated axons for very fast transmission. Precise somatotopic org.
DCMLS senses
2-point, vibration, proprio, discriminative touch
Primary afferents of DCMLS enter SC
on medial division of the posterior root and then branch into medial/lateral. Medial goes up, lateral to various post. horn synapses.
SC lesion would result in what re DCMLS?
ipsilateral reduction/loss of discriminative, positional, vibratry sensation at and bemow level of injury
Sensory ataxia
loss of muscle stretch tendon reflexes, proprio loss of extremities due to lack of sensory input. Pt wide based stance, feet on floor with force to create missing proprio input
Gracile & Cuneate nucleus are located…
In posterior, caudal medulla; recieve info from ipsilateral 1st order neurons (cell body DRG)
After synapsing in nuclei PCMLS become 2nd order neurons. path:
Internal arcuate fibers loop anteromedially in medulla, cross midline as sensory decussation and ascend as Medial lemniscus on opposite side
In the pons, the ML…
rotates laterally, UE fibers medial, LE fibers laterally.
Blood supply in rostral medulla for DCMLS
Anterior spinal artery
From ML fibers go to thalamus where?
Caudal thalamus, VPL/VPM-somatotopic org maintained in VPL
Thalamus blood supply at VPL:
thalamogeniculate branches of PCS. Lesion result in loss of all tactile sensation over contralateral body and head.
3rd order neurons path
traverse posterior limb of IC to S1 and S2 (primary and secondary somatosensory cortices
Parietal cortical regions
also receive tactile input, lesions produce agnosia
agnosia
contralateral body regions lost from body map, sensation not radically altered. ‘Don’t know what limb is doing”
Principal sensory trigem nucleus modality
Discriminative, tactile and proprio of face
Principal sensory trigem nucleus location and blood
Pons; Superior cerebellar and long circumferential branches of basilar aa
Principal sensory trigem nucleus path to thalamus
branch: Ventrolateral division (V123) cross to form anterior TTT. Dorsomedial (oral cavity) project ipsi via posterior TTT
Mesencephalic trigem nucleus modality
proprio of TMJ, Masticatory and extraocular muscles.
jaw-jerk reflex
stretch masseter muscle to contract bilateral
afferent: mesencephalic
efferent: trigem motor
amplitude of reflex enhanced with UMN damage
