What type of fibers are found in the deep layer of Hirano's model?

The deep layer of Hirano's model, which is an important aspect of understanding the structure of the lamina propria of the vocal folds, is characterized by thick collagenous fibers. These fibers provide structural support and strength, essential for the vibratory function of the vocal folds. The presence of thick collagenous fibers contributes to the stiffness and resistance to deformation during phonation, which is crucial for regulating the pitch and amplitude of sound production. Their less elastic nature allows for a stable framework that can withstand the mechanical stresses encountered during vocalization.

In contrast, the other types of fibers mentioned in the other options do not accurately represent the composition of the deep layer in Hirano's model. Elastic fibers, while important, are more prevalent in superficial layers where flexibility is necessary. Loose fibers with fluid spaces play a role in the superficial layer, allowing for mobility and vibration. Cobweb-like fibers do not accurately describe the structure found in the deep layer, as they are not representative of the dense, robust composition needed for the proper function of the vocal folds.