Test 1 Flashcards
Paresis =
Weakness (partial)
Plegia =
No voluntary movement
Paralysis =
No voluntary movement
Palsy =
Weakness or no movement
Hemi-
One side of body
Para-
Both legs
Mono-
One limb
Di-
Both sides of body equally affected
Quadra- or Tetra-
All four limbs
UMN cell bodies are located in the…
Cell bodies in motor cortex or brainstem.
LMN cell bodies are located in the…
Spinal cord and brainstem.
UMN project to…
Projections descend within the CNS to govern activity of lower motor neuron cell bodies.
LMN project to…
Project to muscles in the periphery.
Can you have damage to the CNS if you only damage a LMN?
Yes! This is due to the LMN cell bodies residing in the spinal cord and brainstem.
What is the most common type of LMN and what is their target?
Alpha motor neuron; skeletal muscle.
UMNs are divided into…
Medial and lateral motor systems
Difference between Lateral Motor System vs Medial Motor System.
Lateral motor system descends in the lateral column of the spinal cord and synapses on lateral ventral horn motor neurons and interneurons. These are going to control DISTAL limb muscles. Medial motor system descends in the medial column of the spinal cord and synapse on medial ventral horn and interneurons. These control PROXIMAL axial muscles.
What does somatotopic mean?
How the cortex is organized by brain regions.
True or False: Medial motor systems only synapse ipsilaterally.
False: Medial motor systems can synapse both ipsilaterally and bilaterally.
What are the tracts that make up the lateral motor system?
Lateral corticospinal tract and rubrospinal tract.
What are the tracts that make up the medial motor system?
Anterior corticospinal tract, vestibulospinal tracts (medial and lateral), reticulospinal tracts, and tectospinal tract.
Why are all the descending motor pathways tracts?
They only consist of a single UMN with no synapses.
The two lateral motor systems descend in the CONTRALATERAL or IPSILATERAL lateral spinal cord. The two lateral motor systems control the CONTRALATERAL or IPSILATERAL extremities.
Contralateral, contralateral.
Descending motor systems are functionally organized into what two types of tracts?
Pyramidal tracts and extrapyramidal tracts.
What are pyramidal tracts? What tracts are included?
They originate in the cortex and control VOLUNTARY movement. They terminate on LMN cell bodies in the brainstem and spinal cord. The corticobulbar and corticospinal tracts are included.
What are extrapyramidal tracts? What tracts are included?
They originate in the brainstem and control INVOLUNTARY and AUTOMATIC movement. Tracts include the rubrospinal, vestibulospinal, reticulospinal, and tectospinal.
How are tracts named?
Based on their origin-destination.
Will you see direct UMN signs when you damage pyramidal tracts? Extrapyramidal?
If you damage the pyramidal tract, you will present with UMN signs. If you damage the extrapyramidal tract, you will not see DIRECT UMN signs.
Lateral Corticospinal Tract:
Origin-
Decussation-
Level of termination-
Function-
Origin- primary motor cortex
Decussation- decussation of pyramids
Level of termination- lateral ventral horn, entire cord
Function- voluntary movement of contralateral limbs
At the decussation of pyramids, what happens to the fibers of the lateral corticospinal tract?
85% of the fibers cross, others continue as anterior corticospinal tract.
Somatotopic organization in the cortex for the arms and legs? All other levels?
Cortex: legs medial, arms lateral
All other levels: legs lateral, arms medial
What cranial nerves cross at the level of the cranial nerve nuclei? How are these different compared to the rest of the corticobulbar fibers?
CN V - trigeminal, muscles of mastication: upper pons
CN VII - facial, lower facial muscles - lower pons
CN XII - hypoglossal, tongue protrusion: medulla
The rest of the corticobulbar fibers will affect the left and right fibers. If we damage the fibers on the left, we may see nothing because the fibers on the right can compensate and “hide” the symptoms.
Rubrospinal tract:
Origin-
Decussation-
Level of termination-
Function-
Origin- red nucleus
Decussation- ventral tegmental decussation (midbrain)
Level of termination- lateral ventral horn and intermediate zone, cervical cord
Function- movement of contralateral upper limb
Anterior Corticospinal tract:
Origin-
Decussation-
Level of termination-
Function-
Origin- primary motor cortex
Decussation- some remain ipsilateral, some cross in the ventral white commissure of the spinal cord
Level of termination- cervical and upper thoracic cord
Function- bilateral axial and girdle muscles
Medial Vestibulospinal tract:
Origin-
Decussation-
Level of termination-
Function-
Origin- medial and inferior vestibular nuclei
Decussation- descends bilaterally
Level of termination- cervical and upper thoracic cord
Function- positioning of the head and neck
Lateral Vestibulospinal tract:
Origin-
Decussation-
Level of termination-
Function-
Origin- lateral vestibular nucleus
Decussation- does not cross
Level of termination- entire cord
Function- balance
