The fibular head is the expanded, proximal end of the fibula, located in the lower leg. It serves as a powerful anchor point for several muscles and ligaments, despite the fibula bearing relatively little of the body’s weight during movement. Its structural integrity is directly related to the stability and coordinated function of both the knee and ankle joints.
Location and Role of the Fibular Head
The fibular head is positioned on the lateral side of the leg, just below the knee joint. It is the topmost part of the fibula, the smaller of the two lower leg bones. The head features a flattened superior surface that articulates with the lateral condyle of the tibia, forming the proximal tibiofibular joint.
This synovial joint allows for slight, synchronized movements between the two bones. While the tibia absorbs the majority of the body’s weight, the fibula’s primary role is to provide a stable attachment site for muscles. This arrangement ensures that forces are distributed and controlled across the knee and ankle.
Specific Muscles That Attach to the Fibular Head
The fibular head acts as a junction for the insertion of one major muscle and the origin of several others. The most prominent attachment is the terminal insertion of the biceps femoris tendon, a powerful muscle belonging to the hamstring group. The tendon of the biceps femoris firmly attaches to the styloid process and the lateral aspect of the fibular head.
This attachment is considered the primary insertion point for the long head of the biceps femoris muscle. The fibular head also serves as the origin point for the fibularis longus muscle, formerly known as the peroneus longus. This muscle arises from the lateral side of the fibular head before descending along the leg.
A third muscle that attaches here is the soleus, a broad muscle deep to the gastrocnemius in the calf. The soleus muscle originates from the posterior aspect of the fibular head and the upper third of the fibula’s shaft.
Functional Importance and Common Injuries
Functional Roles
The collective action of the muscles attached to the fibular head governs a wide range of lower limb movements. The biceps femoris is a knee flexor and hip extender, enabling movements like bending the knee or lifting the leg backward.
The fibularis longus is primarily responsible for ankle eversion (outward rotation of the foot) and contributes to plantarflexion (pointing the toes downward). The soleus muscle, originating partly from the posterior fibular head, is a major contributor to ankle plantarflexion, especially when the knee is bent. These muscles work together to control stability, propulsion, and balance during walking, running, and jumping.
Common Injuries
When these muscles contract suddenly or forcefully, the fibular head is susceptible to an avulsion fracture. This occurs when the strong pull of the biceps femoris tendon tears a fragment of bone away from the main structure.
The common fibular nerve (also called the common peroneal nerve) wraps closely around the neck of the fibula, just below the head. Due to this superficial location, the nerve is vulnerable to compression or direct trauma, such as a localized blow or prolonged pressure. Injury to this nerve can result in “foot drop,” which is the inability to lift the front part of the foot, along with sensory deficits along the lateral aspect of the lower leg.