Motorneuroscience Flashcards
Parts of the Brain
- Spinal Cord
- Brainstem
- Cerebellum
- Diencephalon
- Cerebral Hemispheres
Spinal Cord
- Lowest level on the perception/action chain
- Spinal reflexes
- Has afferent and efferent signals
Parts of the Brainstem
- Medulla
- Pons
- Midbrain
Function of the Brainstem
- Postural control
- Locomotion
- Lots of facial connections via cranial nerves
- Arousal and awareness
Cerebellum Input Reception
- Receives input from spinal cord (feedback about movements)
- Receives input from cerebral cortex (planning about movements)
Function of Cerebellum
Adjust motor responses based on comparison of sensory feedback
Parts of the Diencephalon
- Thalamus
- Hypothalamus
Function of the Thalamus
- Receives almost all info going to the cortex
- Acts as a relay station
Function of the Hypothalamus
Governs the endocrine system
Parts of the Cerebral Hemispheres
- Cerebral Cortex
- Basal Ganglia
Function of Cerebral Cortex
Programming movements
Areas of the Basal Ganglia
- Caudate nucleus
- Putamen
- Globus pallidus
- Substania Nigra
Function of Basal Ganglia
Plan and execute movement
Resting Membrane Potential of a Neuron
-70 mV
Types of Synaptic Transmission
- Summation
- Synaptic Facilitation
- Defacilitation
Types of Summation
- Spatial Summation
- Temporal Summation
Spatial Summation
Multiple neurons send PSPs, leading to an action potential
Temporal Summation
A single neuron repeatedly sends PSPs in rapid succession, leading to an action potential
Synaptic Facilitation
-
Defacilitation
-
Sensory/Perceptual Systems
-
Peripheral Receptors
- Muscle Spindle
- Golgi Tendon Organ
- Cutaneous Receptors
Muscle Spindle Function
- Concerned with determining muscle length/stretch
- Acts as a protective measure to prevent injury
- Important for muscle tone
Where is the highest concentration of muscle spindles found?
In the eyes, neck, and hands
Muscle Spindle Composition
- Intrafusal fibers
- Afferent Fibers
- Gamma Motor Neurons
Intrafusal Fibers
Nuclear bag
- Clumped (what’s clumped?)
Nuclear chain
- Lined up (what’s lined up?)
Afferent Neurons of the Muscle Spindle
Ia
- Connects to nuclear bag and chain
II
- Connects to nuclear chain
Gamma Motor Neurons
Gamma Dynamic
- Connects to nuclear bag
Gamma Static
- Connects to nuclear bag and chain
What are alpha motor neurons?
- The efferent nerves that innervate extrafusal muscle fibers (skeletal muscle)
- GMNs intertwine with AMNs
Golgi Tendon Organ
- Innervated by Ib afferent neurons
- No efferent neuron found in the GTO
Function of the GTO
-
Cutaneous Receptor Function
- Reflexes
- Proprioception
- Sensations
Ascending Pathways
- Dorsal Column-Medial Lemniscal System
- Anterolateral System
Sensory Information for the DCML
- Fine touch
- Vibration
- 2-point discrimination
- Proprioception
Decussation Point of DCML
Medulla
3-Neuron Relay
- 1st order neuron (primary) conveys info from the receptors to the medulla
- 2nd order neuron (secondary) conveys info from the medulla to the thalamus
- 3rd order neuron (tertiary) conveys info from the thalamus to the cerebral cortex
1st Order Neuron
Includes many collateral branches entering the gray matter
2nd Order Neuron
Includes:
- Cell bodies located in the nucleus gracilis or cuneatus
- Axons that cross the midline as the internal arcuate fibers (which then ascend to the thalamus)
3rd Order Neuron
Includes:
- Neurons that connect the thalamus to the sensory cortex
- Neurons that have axons forming part of the thalamocortical radiations
Thalamocortical Radiation
Fibers connecting the thalamus to the cerebral cortex
Parts of the Dorsal Column
- Fasciculus Gracilis
- Fasciculus Cuneatus
- F. Gracilis + F. Cuneatus = Funiculus
Fasciculus Gracilis
- Sensory info for lower body
- Medial
- Senses at T6 and down (still present superior to this)
Fasciculus Cuneatus
- Sensory for upper body
- Lateral
- At T5 and up
White Matter
- Acts as “stairs” for sensory info (sends info up and down)
- Funiculus = white matter
- Column = white matter
Gray Matter
- Acts as a “floor” for sensory info (info moves across)
- Horn = gray matter
Medial Lemniscus
-
Function of the Anterolateral System
- Deals with pain
- Minor role in crude touch and pressure
- Thermal?
- Nociception (tissue damage)?
Tracts of the Anterolateral System
- Spinothalamic Tract (our focus)
- Spinoreticular Tract
- Spinomesencephalic Tract
Spinothalamic Tract
Primary, fast, sharp, localized pain
Spinoreticular Tract
- Stops at midbrain
- Arousal response to pain
- Slower than spinothalamic tract
Spinomesechephalic Tract
- Stops at midbrain
- Slow, radiating pain
- Slowest tract for pain
Somatosensory Cortices
-
Association Cortices
-
Functions of the Visual System
- Exteroceptive Sense
- Visual Propriception
Exteroceptive Sense
Vision allows us to identify objects in space and determine their movements
Visual Proprioception
Allows us to know where our bodies are in space through visual stimuli