Final answer:
Golgi tendon organs contain type Ib nerve fibers that sense changes in muscle tension.
Step-by-step explanation:
The type of nerve fibres found in Golgi tendon organs are Ib fibers. These nerve fibers are responsible for sensing changes in muscle tension, helping to prevent muscle damage from excessive force. Golgi tendon organs are proprioceptive sensory receptors located at the junction of muscles and tendons. When the muscle contracts, the tendon pulls on the Golgi tendon organ, and the Ib fibers become activated, sending signals to the spinal cord to inform about the tension.