6.1 Neuro Anatomy & Physiology - The Spinal Cord and Motor Control Flashcards
Fundamentally, what is the spinal cord?
A column of nervous tissue (2-way highway)
What is the diameter of the spinal cord?
1mm
What is the function of the spinal cord?
Connects brain to PNS
Where does the spinal cord run to/from?
Brainstem to lumbar region
What are the two main tracts of the spinal cord? What type of input do these two tracts carry?
Ascending tract: sensory/afferent
Descending tract: motor/efferent
What type of input does the dorsal root carry?
Sensory input (afferent)
What type of input does the ventral root carry?
Motor (efferent)
What makes up grey matter?
- Cell bodies
- Neuroglia
- Unmyelinated axons
How does CSF flow through the spinal cord?
Through the central canal
What is the spinal nerve?
The joining of the ventral and dorsal roots at a distance away from the spinal cord itself. These two only branch apart near the spinal cord.
What is a dorsal root ganglion?
Collection of sensory neuron cell bodies
What is the grey commissure? What type of axons does it contain, and why does this make sense?
- Connects two sides of the spinal cord
- Unmyelinated axons; makes sense: grey
What is the difference between somatic and visceral neurons?
Somatic: Conscious control
Visceral: Internal organs (viscera)
What is the function of the neurons in the lateral horn of the spinal cord?
Autonomic functions
What are the three white matter tracts/funiculi of the spinal cord?
- Dorsal
- Lateral
- Ventral
What is the dorsal column responsible for?
Sensory function
What is the lateral column responsible for?
Sensory and motor function
What is the ventral column responsible for?
Sensory and motor function
Which type(s) of muscles drive somatic muscle activity?
Skeletal
Which type(s) of muscles drive visceral muscle activity?
Cardiac and smooth
Which brain structures are commonly associated with motor movement?
Brain and spinal cord (CNS)
Which brain structures add context and meaning to motor movement?
- Basal ganglia
- Cerebellum
What are the two types of motor neurons?
Upper and lower
Where are upper motor neurons found?
Motor cortex (pre-central gyrus)
Where do lower motor neurons originate? What tracts do they make up?
Brainstem and spinal cord. They make up the descending tracts.
In which two enlargements of the spinal cord can lower motor neurons be found? What do these correlate with?
- Cervical enlargement
- Lumbar enlargement
This correlates with the upper and lower limbs
What muscle fibres do alpha motor neurons supply?
Extrafusal (main muscle mass)
Which three sources do alpha motor neurons recieve input from?
- Muscle spindles
- Spinal interneurons
- Upper motor neurons
What are the two types of lower motor neurons?
- Alpha
- Gamma
Which muscle fibres do gamma motor neurons supply?
Intrafusal muscle fibres/muscle spindles/proprioceptors
What do intrafusal muscle fibres do?
Detect the amount and rate of change in muscle length. This information is then fed back to the spinal cord for processing
What is the name of sensory inputs that are given to the motor unit?
Proprioceptive information/input
What are the two sources of proprioceptive information in muscles?
- Muscle spindles
- Golgi tendon organs
What do golgi tendon organs detect? What kind of neurons do they sinapse with?
- They detect muscle tension
- They synapse with inhibitory internurons, thus preventing further contraction and stopping the muscle from snapping.
What can interneurons recieve input from?
- Descending upper motor + collaterals of lower motor neurons
- Sensory axons
- Other interneurons
What is in Brodman’s area 6? What do these structures do?
- Pre-motor areas
- Supplementary motor areas
Involved in planning and initiation of movement.
How does the prefrontal cortex help with motor movement?
Important in planning and decision making
How does the posterior parietal lobe help with motor movement?
Helps integrate sensory input with motor function
What is another name for the pyramidal motor system? What is it involved in?
Corticospinal tract; motor planning and initiation
Where do motor neurons decussate?
Lower medulla (pyramids)