Knock knee, flat foot, and round shoulders are deformities associated with the skeletal system.

Explanation:
The skeletal system is responsible for providing support, structure, and protection to the body. It consists of bones, cartilage, ligaments, and tendons. Any abnormalities or deformities in this system can affect the overall posture and movement of an individual.

Knock Knee:
Knock knee, also known as genu valgum, is a condition where the knees angle inward and touch each other when the legs are straightened. This deformity occurs due to an imbalance in the growth of the bones in the lower legs, causing the knees to bend inward. It can be caused by various factors such as genetics, bone disorders, or nutritional deficiencies.

Flat Foot:
Flat foot, also known as pes planus, is a condition where the arches of the foot collapse, causing the entire sole of the foot to touch the ground. This deformity can be congenital or acquired and can be caused by weak or stretched ligaments, muscle imbalances, or certain medical conditions. Flat foot can lead to foot pain, instability, and difficulty in walking or running.

Round Shoulders:
Round shoulders, also known as kyphosis or slouched posture, is a condition where the shoulders are rounded forward, causing the upper back to appear hunched. This deformity can be caused by poor posture, muscle imbalances, weak back muscles, or certain medical conditions. Round shoulders can lead to back pain, limited mobility, and an unattractive posture.

Conclusion:
In conclusion, knock knee, flat foot, and round shoulders are deformities associated with the skeletal system. These conditions can have various causes and can affect the posture and movement of an individual. It is important to address these deformities through appropriate medical interventions, exercises, and therapies to improve overall skeletal health and functionality.