Motor pathways Flashcards
What do motor nerves do?
Voluntary control of movement via skeletal muscle - efferent
What does the motor pathway do?
- Synapses with LMN to take signal from spinal cord to muscle
- UMN is from motor cortex to spinal cord
Motor cortex blood supply
Anterior/medial posterior cerebral arteries
What is the motor cortex formed from?
Grey matter
Where does the motor neuron cross to the contralateral side?
Medulla pyramids
When are mixed nerved formed?
From the horizontal articular surface, where afferent nerves from the dorsal horn and efferent nerves from the ventral horn combine
Where does the right corticospinal tract decussate?
Anterior corticospinal tract
Which side of the body does the right motor cortex innervate?
LHS
Where does the anterior corticospinal tract decussate?
At exit level in spinal cord
Where does the lateral corticospinal tract decussate?
Pyramids
What does the anterior CST supply?
Neck and upper limbs
Fine movements
What is a motor unit?
A motor neuron and all the muscle fibres it innervates
Myotome for shoulder abduction
C5
Myotome for elbow flexion
C5-C6
Myotome for wrist extension
C6-C7
Myotome for finger flexion/extension
C7, C8
Myotome for finger abduction/adduction
T1
Myotome for hip flexion
L2-L3
Myotome for hip extension
L4-L5
Myotome for knee flexion
L2-L3
Myotome for knee extension
L3-L4
Myotome for ankle dorsiflexion
L4-L5
Myotome for ankle plantar flexion
S1-S2
How does the stretch reflex work?
- Muscle groups generally work in pairs - flexors/extensors, abductors/adductors etc
- Contraction of one stretches the other passively - a reflex arc that tenses the stretched muscle
- Provides muscle tone and stability
- 2 nerves and 1 synapse - very fast (monosynaptic stretch reflex)
