Cartilage as the cricoid cartilage and carina. Cartilage is composed of specialized cells called chondrocytes that produce a large amount of collagenous extracellular matrix, abundant ground substance that is rich in proteoglycan and elastin fibers. Cartilage is classified in three types, "elastic cartilage", "hyaline cartilage" and "fibrocartilage", which differ in relative amounts of collagen and proteoglycan. Cartilage does not contain blood vessels (it is avascular) or nerves (it is aneural). Nutrition is supplied to the chondrocytes by diffusion. The compression of the articular cartilage or flexion of the elastic cartilage generates fluid flow, which assists diffusion of nutrients to the chondrocytes.
Cartilage conduction conduction is accounted for by sound (vibration) energy stimulating the cartilage at the external auditory canal to create sonic waves in the ear canal. Such sonic wave energy passes through the eardrum and the middle ear before finally activating the auditory nerve. These different mechanisms would explain the following observed differences between cartilage and bone pathways: 1. A variety of sound pressure levels can be created by contact pressure in cartilage conduction compared with that in bone conduction. 2. A sound in cartilage conduction is more stereophonic than that in bone conduction. 3. Frequency characteristics are different between cartilage and