To better understand leg swelling (unilateral), it helps to understand the anatomy of the leg.

The entire leg contains four bones:

• Femur:
• The thighbone
• Patella:
• The kneecap
• Tibia:
• A thick bone in the front of the lower leg
• Fibula:
• A thin bone on the side of the lower leg

The thigh contains the largest bone in the body, called the femur. The femur begins at the hip and ends at the knee. The muscles of the thigh control movement of the knee and hip. The patella, or kneecap, protects the front of the knee.

The lower leg contains two long bones, called the tibia and fibula. The muscles of the lower leg control movement of the foot and ankle.

Leg anatomy examples:

• Muscles and bones of the leg
• Muscles of the buttock and thigh
• Regions of the lower leg where tenderness may be a sign of a fracture
• Internal structures of the knee