The fibular head is the upper, rounded end of the fibula, the thinner of the two long bones in the lower leg. This palpable bony prominence is found on the outside (lateral side) of the leg, positioned just beneath the knee joint. It connects the fibula to the tibia and serves as an anchor point for multiple soft tissues, playing a functional role in stabilizing the lower limb.
Anatomical Position and Skeletal Connections
The fibular head is located proximally and distinctly lateral in the lower leg. It sits immediately below the knee joint, on the outer aspect of the leg, where it can often be felt beneath the skin. This expanded upper portion of the fibula forms an articulation with the tibia, the much larger shin bone, but is not part of the main knee joint itself. This connection is known as the proximal tibiofibular joint, where the fibular head meets the lateral condyle of the tibia. Strong ligaments reinforce the joint, ensuring the two bones remain connected throughout movement. While the tibia is the primary weight-bearing bone of the lower leg, the fibula primarily offers structural support and a surface for muscle attachment. The articulation permits slight movements, which accommodate forces transmitted up from the ankle during activities like walking and running.
Muscle and Ligament Anchor Points
The fibular head functions as an attachment point for several soft tissue structures that influence knee and lower leg movement. One major tendon inserting here is from the biceps femoris muscle, a powerful component of the hamstring group. The tendon wraps around the head of the fibula to attach firmly to the bone, enabling the muscle to assist in knee flexion and hip extension. Furthermore, the fibular head provides the fixed lower attachment point for the Lateral Collateral Ligament (LCL), also known as the fibular collateral ligament. This strong, cord-like ligament extends upward from the fibular head to the femur. The LCL provides stability to the outer side of the knee, resisting forces that attempt to push the knee inward.
Clinical Importance and Nerve Vulnerability
The anatomical placement of the fibular head makes it a location of concern in clinical practice, primarily due to a closely associated nerve pathway. Just below the fibular head, the common peroneal nerve, a major branch of the sciatic nerve, courses around the fibular neck. This nerve is remarkably superficial at this point, covered only by skin, fat, and a thin layer of fascia. Because of this exposed position, the common peroneal nerve is highly susceptible to direct trauma, compression, or stretching injuries from external forces. Pressure from a tight cast, prolonged awkward positioning, or a direct impact to the outside of the knee can easily injure the nerve. Damage to the nerve often results in “foot drop,” characterized by weakness in the muscles that lift the front of the foot. The fibular head can also suffer an avulsion fracture, where a sudden, forceful contraction of the biceps femoris muscle pulls a small fragment of bone away at the tendon’s insertion point.