Final answer:
Prolonged postural strain can affect ligaments and costal cartilage. Ligaments can gradually lengthen and weaken, leading to pain and instability in joints. Costal cartilage may be indirectly affected if there are imbalances or abnormalities in posture.
Step-by-step explanation:
With prolonged postural strain, ligaments and costal cartilage can be affected. Ligaments are fibrous connective tissues that attach bones to each other, providing stability and support to joints. Prolonged strain on ligaments can lead to gradual lengthening and weakening, which can result in pain and instability in the affected joint. Costal cartilage, on the other hand, refers to the cartilage that connects the ribs to the sternum. While it is less likely to be directly affected by postural strain, it can still experience stress or strain if there are imbalances or abnormalities in the posture.