Golgi Tendon Organs Overview

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Questions and Answers

What role do Golgi Tendon Organs (GTOs) play in monitoring muscle activity?

GTOs monitor muscle force and tension produced during active muscle contraction.

How do GTOs respond to passive muscle stretch versus active contraction?

GTOs are insensitive to passive muscle stretch but reflect muscle activity better during active contraction.

Describe the relationship between GTO firing rates and muscle force.

GTO discharge rate is approximately linear and scales with increasing muscle force.

What is the significance of the GTO population code?

The GTO population code provides a better representation of muscle force by integrating input from multiple motor units. Signup and view all the answers

Explain the feedback pathway provided by GTOs to the central nervous system.

GTOs provide feedback to the spinal cord through Ib afferents, facilitating inhibitory connections to motoneurons. Signup and view all the answers

What is autogenic inhibition and its relation to GTOs?

Autogenic inhibition refers to the inhibition of the agonist muscle facilitated by GTOs during high tension. Signup and view all the answers

How do GTOs integrate input from different sources?

GTOs receive input from cutaneous, joint receptors, and descending pathways to modulate their response. Signup and view all the answers

Why might the term 'Ib inhibitory interneuron' be considered misleading in the context of GTOs?

The term is misleading because the interneuron also receives inputs from various sources beyond just GTOs. Signup and view all the answers

Where are Golgi Tendon Organs (GTOs) located in relation to muscle fibers?

GTOs are located at the tendon junction, in series with the muscle fibers. Signup and view all the answers

What type of afferent fiber innervates the Golgi Tendon Organ?

The afferent fiber that innervates the GTO is the 1B afferent. Signup and view all the answers

How do GTOs differ from muscle spindles in terms of their location and structure?

GTOs are located at the junction of tendons and muscles and are arranged in series, whereas muscle spindles are spread throughout the muscle belly and lie parallel to muscle fibers. Signup and view all the answers

What do Golgi Tendon Organs primarily code for in relation to muscle function?

GTOs primarily code for muscle force or tension. Signup and view all the answers

What level of force is necessary to activate a GTO during passive stretch compared to muscle fiber activation?

Passive stretch requires approximately 2 Newtons to activate a GTO, while activation of a single muscle fiber requires only 30-90 millinewtons. Signup and view all the answers

What percentage of GTOs have two Ib afferents innervating them?

Approximately 2% of GTOs have two Ib afferents. Signup and view all the answers

In what way do Golgi Tendon Organs contribute to muscle sensitivity during contraction?

GTOs are sensitive to muscle contraction, responding to increased tension generated during muscle twitches. Signup and view all the answers

What is one of the primary roles of the Golgi Tendon Organ in relation to the central nervous system?

GTOs provide feedback to the CNS about muscle force or tension. Signup and view all the answers

Study Notes

Golgi Tendon Organs (GTOs)

GTOs are located at the tendon junction
Spindles are spread throughout the muscle belly
Spindles lie parallel to muscle fibres, GTOs are in series
Capsule is 1mm by 0.1mm
10-20 muscle fibers
Not all muscle fibers pass through a GTO; some are in series and some are in parallel
The afferent fiber that innervates the Golgi tendon organ is the 1B afferent
Each GTO has a single Ib afferent, although 2% of GTOs have 2 afferents
Nerve endings interdigitate among collagen fibers
GTOs are sensitive to muscle contraction
GTOs code for muscle force/tension
Active contraction > passive stretch
GTO population code (ensemble code)
Provide feedback to the CNS via negative feedback pathway

GTO Sensitivity and Unloading

Once thought that GTOs were designed to signal dangerously high force levels
However, the force needed to excite a GTO depends on activation mode
Passive stretch requires approximately 2 Newtons
Activation of a single muscle fibre requires 30-90 millinewtons, which will also activate the GTO
Therefore, GTOs are more sensitive to actively generated forces than passive forces

GTO Response to Muscle Contraction

GTOs respond linearly to muscle force
In series versus parallel response to muscle shortening and increased tension in a twitch

GTO Feedback

GTOs provide feedback to the spinal cord via Ib afferents
Disynaptic connection to motor neurons
Ib inhibitory interneurons
Perhaps an inappropriate name as this interneuron gets input from cutaneous, joint, and many descending sources
Autogenic inhibition: inhibits agonist muscle.

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Description

Explore the structure and function of Golgi Tendon Organs (GTOs), which are critical for sensing muscle force and tension. This quiz covers their location, sensitivity, and role in providing feedback to the central nervous system. Delve into the details of their afferent innervation and population coding.