Lecture 12: Motor Tracts (Keim) Flashcards
What are the signs for upper motor neuron damage?
- Upper
- Hyperreflexia
- Babinski
- Loss of strength and dexterity
- Spasticity
- Rigidity
- Pronator Drift
What are the signs for lower motor neuron damage?
- Lower
- Flaccid paralysis
- Muscle wasting
- Hyporeflexia / areflexia
- Denervation hypersensitivity or fasciculations
What is the orientation of proximal / distal and flexors vs extensor fibers in the anterior horn?
The proximal motor neurons (trunk) are more medial, and distal motor neurons are more lateral.
Also flexors are more posterior, and extensors are more anterior.
What are the two lateral indirect upper motor neuron pathways?
Rubrospinal tract
Lateral reticulospinal tract
What is the function of the medial vestibulospinal tract?
The medial vestibulospinal tract is found in the mid and lower vestibular nuclei in the medulla, and innervates ipsilateral neck and shoulder muscles.
What is the function of the lateral vestibulospinal tract?
The lateral vestibulospinal tract can be found in the upper vestibular nuclei in the pons, and innervates the ipsilateral muscles of posture and the limb extensors.
What is the function of the tectospinal tract?
Turns one’s head toward sound and pointing the head where the eyes are pointed.
What is the function of the lateral reticulospinal tract?
The reticulospinal tract facilitates flexor motor neurons and modulates extesor mechanisms ipsilaterally.
What is the function of the rubrospinal tract?
The rubrospinal tract innervates the upper limb flexors contralaterally.
Where do the fibers of the lateral corticospinal tract arise from?
Primary motor cortex
Supplementary motor area
Premotor cortex
ALSO
Primary somatosensory cortex
Parietal association cortex
What is the path of the fibers of the lateral corticospinal tract pathway from cortex to spinal cord?
Cortex
Posterior limb of internal capsule
Midbrain in the middle 1/3 of the cerebral peduncles.
Pons
Pyramids in the medulla
Decussation of pyramids
Lateral column of the spinal cord
Synapse with LMN in the ventral horn of the spinal cord.
What is the somatotopic organization of the fibers from the lateral corticospinal tract as they pass through the posterior limb of the internal capsule?
Same as the anterolateral system
The lower fibers are more lateral (posterolateral to be precise)
What arteries supply the internal capsule?
Lenticulostriate arteries off the middle cerebral A.
What artery supplies the corticospinal tract in the midbrain?
In the pons?
In the medulla?
Corticospinal tract arteries:
Midbrain – posterior spinal A.
Pons – paramedian branches of basilar A.
Medulla – sulcal branches of anterior spinal A.
What motor nuclei are present in the pons?
VII and V motor
