Final answer:
A synchondrosis is a cartilaginous joint with hyaline cartilage, seen in the epiphyseal plate of growing bones or the first sternocostal joint. A symphysis involves fibrocartilage, such as the manubriosternal joint or intervertebral disc. Both allow limited movement and are types of synarthrosis.
Step-by-step explanation:
A synchondrosis is a type of cartilaginous joint where bones are united by hyaline cartilage. One prominent example of a temporary synchondrosis is the epiphyseal plate (growth plate) in growing long bones, which is replaced by bone in adulthood (a process called synostosis). An example of a permanent synchondrosis is the first sternocostal joint, where the first rib meets the manubrium.
Conversely, a symphysis is a cartilaginous joint where bones are connected by fibrocartilage. The manubriosternal joint and the pubic symphysis are examples of narrow symphyses, and the intervertebral disc of adjacent vertebrae is an example of a wide symphysis.
Both synchondroses and symphyses allow for very little movement, classifying them as types of synarthrosis.