Final answer:
Option D. The scapulothoracic joint is considered a functional joint in the shoulder complex that is not a true synovial joint. It allows for the scapula's smooth gliding over the rib cage, which is crucial for shoulder movement.
Step-by-step explanation:
The joint in the shoulder complex that is not technically a synovial joint but is considered a functional joint is the scapulothoracic joint. This joint is formed by the articulation between the scapula and the thoracic wall. While it doesn't have a synovial cavity like other synovial joints, it allows for movement and is essential for the proper functioning of the shoulder complex.
The joint in the shoulder complex that is not "technically" a synovial joint but is considered a functional joint is the scapulothoracic joint. Unlike the glenohumeral, sternoclavicular, and acromioclavicular joints, which are true synovial joints with synovial membranes and joint cavities, the scapulothoracic joint is formed between the scapula and the thoracic rib cage.
This joint does not have the typical features of a synovial joint as it's more of a physiological joint created by muscle interactions, yet it is important for shoulder function allowing for a smooth gliding of the scapula over the rib cage during shoulder movements.