Physiology V: Motor Units, Muscle Spindles, Golgi Tendon Organs and Joint Receptors

When do motor neurons switch from being upper motor neurons to lower motor neurons?

Which type of motor neurons innervate the bulk of fibres within a muscle responsible for contractile force?

Which type of motor neuron innervates a sensory organ within the muscle responsible for reacting to muscle stretch?

The sensory organ within a muscle that detects changes to muscle length and responds to stretch is called the muscle [blank_start]spindle[blank_end]

Muscles that work together to perform a function are called ... E.g. Biceps brachii and brachialis working together to perform flexion of the forearm

An α-motor neuron and all of the skeletal muscle fibres that it innervates are collectively known as a [blank_start]motor unit[blank_end]

The collection of α-motor neurons that innervate a muscle is called a motor neuron [blank_start]pool[blank_end]

A single action potential in an α-motor neuron causes a muscle fibre to '[blank_start]twitch[blank_end]'

Sustained contraction of a muscle due to action potentials being fired at a very high rate is known as [blank_start]tetanus[blank_end]

Match the skeletal muscle fibre type to its description: [blank_start]Type I Skeletal Muscle Fibre[blank_end]: ATP derived from oxidative phosphorylation. Slow contraction and relaxation. Fatigue Resistant. [blank_start]Type IIa Skeletal Muscle Fibre[blank_end]: ATP derived from oxidative phosphorylation. Fast contraction and relaxation. Fatigue Resistant. [blank_start]Type IIb Skeletal Muscle Fibre[blank_end]: ATP derived from glycolysis. Rapid contraction but not fatigue resistant.

Of the different types of skeletal muscle fibres, which is pale/white in colour

When a skeletal muscle is pulled, the muscle spindles inside that muscle react causing the muscle to resist stretch by pulling back. This is called the [blank_start]myotatic[blank_end] reflex.

[blank_start]Intrafusal[blank_end] skeletal muscle fibres are found in the muscle spindle and are innervated by [blank_start]gamma[blank_end] motor neurons

At the junction of muscle and tendon, in series with extrafusal fibres, lie small 'organs' which monitor changes in muscle tension. These small 'organs' are called [blank_start]Golgi Tendon[blank_end] Organs

What is the function of Golgi Tendon Organs?