What is an innervation ratio?
the ratio expressing the number of muscle fibers innervated by a single motor axon. It may vary from 3 muscle fibers per axon for small muscles in the fingers to 150 muscle fibers per axon for large muscle bundles of the arms and legs. The lower the ratio, the finer is the control of movements.
Which of the following muscles would have motor units with the lowest innervation ratio?
fingers
Out of the above choices, _C_, the muscles that move the fingers would have motor units with the lowest innervation ratio.
Which type of motor unit has the highest innervation ratio?
type IIx motor units
In contrast, type IIx motor units have the highest innervation ratios and a greater capacity for rapid energy production through nonoxidative (i.e., anaerobic) glycolysis, and thus can produce rapid and powerful contractions.
Why is the innervation ratio in the ocular muscles?
The ocular muscles require finer control than moving the legs. The innervation ratio has to do with the overall size of the muscle–the bigger the muscle, the fewer the muscle fibers per motor axon.
What does high innervation mean?
If a muscle is required only for coarse movements (e.g., a thigh muscle), its motor units will tend to have a high innervation ratio (i.e., each motor neuron innervating 1000 or more muscle fibers), as there is no necessity for individual muscle fibers to undergo highly coordinated, differential contractions to produce …
What effect does lack of motor neuron innervation have on skeletal muscle function?
In skeletal muscle, lack of innervation causes severe alterations of fiber properties: general disarrangement of internal structure accompanied by functional impairment and followed by complete degeneration (4–6).
Which of the following statements best describes a muscular force couple?
Which of the following statements best describes a muscular force-couple? The larger a muscle’s cross-sectional area, the greater is its force-producing potential. Regardless of whether a muscle is lengthening or shortening, a muscle can produce only a contractile, or pulling, force.
Why are slow twitch muscles dark?
Myoglobin is a protein in muscle cells that carries oxygen. Since slow twitch muscles need a lot of oxygen to fuel long periods of movement, they have lots of myoglobin. And myoglobin, it turns out, is richly pigmented, meaning an abundance of this protein gives dark meat its brown shading.
Why do you want a small motor unit for fine motor skills?
What structures make up a motor unit? Why do you want a small motor unit for fine motor skills? the small muscles, responsible for finely tuned movements, such as those in the eyes and fingers, have small motor units with few fibers per motor unit. How do muscles relax?
What happens if a muscle is not innervated?
Why is innervation important to a muscle?
When nerves go into muscle fiber, they innervate the muscle fiber. Innervate is to supply nerves to something, but it can also mean to energize. Think of all the energy you have when you get nervous! Sometimes nervousness can even innervate the hairs on your arms, i.e. stimulate them and make them stand up.