PROPERTIES OF THE MOTOR UNIT Flashcards
What is the motor unit?
An alpha (lower) motor neurone and all the extrafusal muscle fibres it supplies as well as the NMJ
What part of the nervous system contains motor units
Somatic - they are somatic efferents
What is muscle tone, what does it do and how is it regulated?
- The amount of tension or resistance to movement in the muscles
- Changes in muscle tone affect the way voluntary movements are created
- Muscle tone is regulated by signals that travel to the brain from nerves which tell the muscle to contract
What is the difference between striated and non striated muscle
Striated muscle - attached to tendons and ligaments and involved in voluntary muscle movement (skeletal and cardiac muscle)
Non - striated muscle - mostly are situated in the lining of inner organs and show involuntary movement (smooth muscle)
Importance of skeletal muscle (3)
- Muscle tone - posture
- Stability of joints
- movements
What is a myocyte
A muscle cell in cardiac or smooth muscle
What is a muscle cell in skeletal muscle called?
muscle fiber
What is a fascicle formed from?
A collection of myocytes
What are myocytes made from?
Lots myofibrils
What do a bunch of fascicli form?
Muscles
What is the name of the connective tissue that ensheathes the myocyte
Endomysium
What is the name of the sheath enveloping the fascicle?
Perimysium
Name of the sheath enveloping all fascicles in a muscle and the neuromuscular bundle.
Epimysium
What is a tendon?
Fibrous connective tissue that connects muscle to bone. It brings the actions of individual myofibrils together so that the myocytes produce combined actions
What are the two types of motor neurones?
- Upper motor neurone
- Lower motor neurone
Lower motor neurones are driven by upper motor neurones
Where are motor neurones in the spinal cord found?
Grey matter
Where are lower motor neurones found?
Cell body in a cranial nerve motor nucleus or the ventral horn of the spinal cord
Give the 3 categories of muscle fibres
Type FF = Fast twitch - fast and easily fatigued
Type FR = intermediate twitch - fast and resistant to fatigue
Type S = Slow twitch
What action is taken by muscles when there is nerve damage?
The muscle cells are persuaded to take up another nerve supply because without it the muscle could die. The characteristic of the nerve influences the muscle
