NB15 Organisaiton of spinal cord Flashcards
What is the difference in function between the muscle spindle and the golgi tendon organ?
Muscle spindle stimulates muscle contraction, whereas golgi tendon organ inhibits muscle contraction.
Which reflex might be acting when an arm adjusts to carrying an increased load?
2Stretch reflex
Which type of afferent fibres are involved in the stretch reflex?
1a fibres
Which reflex will act to release strain on a tendon when it is being overstretched?
Inverse stretch reflex/inverse myotatic reflex/ 1b tendon reflex
What is a central pattern generator?
A set of neurons in the spinal cord capable of regulating certain programmed movements. E.g. chewing, swallowing, etc.
What does a single alpha-motorneurone do?
innervates lots of muscle fibres
What doe gamma-motorneurons do?
activate intrafusal fibres within muscle spindle
How are lower motor neurons organised in the spinal cord?
in the ventral hall laterally controls distal musculature,
mesially controls proximal musculature,
the ventral aspect of the ventral horn controls extensors nad th edorsal aspect of the ventral horn controls flexors
What does
1) muscle spindle
2) Golgi tendon organ
give rise to?
1) 1a afferents
2) 1b afferents
Describe the myotactic reflex:
1) change in muscle length
2) activation of 1a afferents
3) alpha-motoneurons activated
4) muscle contracts
e. g. catch a cup
Describe the inverse stretch or inverse myotactic reflex or 1b tendon reflex:
1) stretch of tendon in muscle= activation of 1b afferetns
2) inhibits activation of the same (homonymous) mm. and activates antagonistic muscle
3) slower than stretch reflex
Describe crossed extensor reflexes:
involved in response to pain
When the reflex occurs the flexors in the withdrawing limb contract and the extensors relax, while in the other limb, the opposite occurs.
stepping on a lego brick
