**Core Concept**
The Golgi tendon organ (GTO) is a proprioceptive sensory receptor located at the junction of skeletal muscle and tendon. It plays a crucial role in detecting changes in muscle tension and stretch.

**Why the Correct Answer is Right**
The GTO is sensitive to increases in muscle tension and stretch. When muscle tension increases, the GTO is activated, sending signals to the central nervous system to regulate muscle contraction and prevent excessive force. This helps maintain muscle homeostasis and prevents injury. The GTO is also involved in the regulation of reflexes, such as the Golgi tendon reflex, which helps to reduce muscle tension and prevent damage.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because the GTO is not primarily responsible for detecting changes in muscle length or stretch. While it is sensitive to stretch, its primary function is to detect changes in muscle tension.
**Option B:** This is incorrect because the muscle spindle is a proprioceptive receptor that detects changes in muscle length and stretch, not muscle tension.
**Option C:** This is incorrect because the GTO does not play a significant role in detecting changes in joint position or movement.

**Clinical Pearl / High-Yield Fact**
The Golgi tendon reflex helps to protect muscles from injury by reducing muscle tension and preventing excessive force. This reflex is an important mechanism for maintaining muscle homeostasis and preventing muscle strain or damage.

**Correct Answer: C. Detecting changes in muscle tension.**