Spinal cord Flashcards
Review of spinal cord and its arrangements
What is the role of the upper motor systems?
Send info to spinal cord and brain stem; initiate voluntary movements
Where are the upper motor systems located?
Motor cortex and brainstem; either directly or under the influence of other brain areas that control movements
What are the lower motor systems?
Grey matter of spinal cord and brainstem; contain lower motor neurones and lower circuit neurones
How long and thick is the spinal cord?
44cm long; 6-13mm thick
Where is the spinal cord situated in spinal column?
Vertebral foramen
Where does the spinal cord end, and why?
L1/L2; spinal cord cells don’t grow more as body grows
In a cross section of the spinal cord, what is the middle part which looks like an H?
Neurones and other cells (grey matter)
In a cross section of the spinal cord, what is the outside of the cord?
Fibres (white matter)
Within the spinal segment, what is the anterior part of the cord called?
Ventral horn; contains motor nuerones
Within the spinal segment, what is the posterior part of the cord called?
Dorsal horn; contains sensory neurones
What is a neural prosthesis?
A system to bypass the output from the damaged spinal cord; in order to do this we have to decode the signals from the brain
What is a motor pool?
All the motor neurones that innervate a single muscle; each fibre innervated by a single neurone
Why do the cervical and lumbar spine have more motor pools?
More controlled movements, thus more muscles
Why does the thoracic spine have fewer motor pools?
Less controlled movements, thus fewer muscles
What is the somatotopic organisation of lower motor neurones?
Proximal muscle neurones located medially; distal muscle neurones located laterally
What is a motor unit?
A single neurone innervating multiple muscle fibres
What are the distinguishing characteristics of slow motor unit?
Small motor neurones
Innervate relatively few muscle fibres
Generate small forces
Innervate small, slow twitch muscle fibres
What are the distinguishing characteristics of fast fatiguable motor unit?
Large motor neurones
Innervate larger, more powerful units
Generate more force
Innervate larger, fast fatiguable muscle fibres
What are the distinguishing characteristics of fast fatigue-resistant motor unit?
Motor units of intermediate size
Not as fast as FF units but less fatiguable
How does physical activity affect types of motor unit?
Due to muscle plasticy, different training can change the type of muscle fibre present in the exercised muscle; paralysis transforms slow twitch fibres to fast twitch
What is implication of more neurones innervating a single muscle?
Finer movements
What are reflexes?
Actions produced at the level of the spinal cord
What is the patellar reflex?
Monosynaptic
What is the withdrawal reflex?
Polysynaptic
